ultra-low-power, 22msps, dual 8-bit adc · 2009. 9. 16. · pd0 exposed paddle pd1 refin com refn...

General DescriptionThe MAX1192 is an ultra-low-power, dual, 8-bit, 22Mspsanalog-to-digital converter (ADC). The device featurestwo fully differential wideband track-and-hold (T/H) inputs.These inputs have a 440MHz bandwidth and accept fullydifferential or single-ended signals. The MAX1192 deliv-ers a typical signal-to-noise and distortion (SINAD) of48.6dB at an input frequency of 5.5MHz and a samplingrate of 22Msps while consuming only 27.3mW. This ADCoperates from a 2.7V to 3.6V analog power supply. A sep-arate 1.8V to 3.6V supply powers the digital output driver.In addition to ultra-low operating power, the MAX1192features three power-down modes to conserve powerduring idle periods. Excellent dynamic performance,ultra-low power, and small size make the MAX1192 idealfor applications in imaging, instrumentation, and digitalcommunications.

An internal 1.024V precision bandgap reference setsthe full-scale range of the ADC to ±0.512V. A flexiblereference structure allows the MAX1192 to use its inter-nal reference or accept an externally applied referencefor applications requiring increased accuracy.

The MAX1192 features parallel, multiplexed, CMOS-compatible tri-state outputs. The digital output format isoffset binary. A separate digital power input accepts avoltage from 1.8V to 3.6V for flexible interfacing to dif-ferent logic levels. The MAX1192 is available in a 5mm× 5mm, 28-pin thin QFN package, and is specified forthe extended industrial (-40°C to +85°C) temperaturerange.

For higher sampling frequency applications, refer to theMAX1195–MAX1198 dual 8-bit ADCs. Pin-compatibleversions of the MAX1192 are also available. Refer to theMAX1191 data sheet for 7.5Msps, and the MAX1193data sheet for 45Msps.

ApplicationsUltrasound and Medical Imaging

IQ Baseband Sampling

Battery-Powered Portable Instruments

Low-Power Video

WLAN, Mobile DSL, WLL Receiver

Features� Ultra-Low Power

27.3mW (Normal Operation: 22Msps)1.8µW (Shutdown Mode)

� Excellent Dynamic Performance48.6dB/47.2dB SNR at fIN = 5.5MHz/125MHz70dBc/69dBc SFDR at fIN = 5.5MHz/125MHz

� 2.7V to 3.6V Single Analog Supply

� 1.8V to 3.6V TTL/CMOS-Compatible DigitalOutputs

� Fully Differential or Single-Ended Analog Inputs

� Internal/External Reference Option

� Multiplexed CMOS-Compatible Tri-State Outputs

� 28-Pin Thin QFN Package

� Evaluation Kit Available (Order MAX1193EVKIT)

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Ultra-Low-Power, 22Msps, Dual 8-Bit ADC

________________________________________________________________ Maxim Integrated Products 1

21 20 19 18 17 16 15

1 2 3 4 5 6 7

8

9

10

11

12

13

14

28

27

26

25

24

23

22

MAX1192

5mm x 5mm THIN QFN

TOP VIEW

PD0

EXPOSED PADDLE

PD1

REFIN

COM

REFN

REFP

VDD

INA+INA-

GND

CLK

GND

INB+

INB-

VDD

VDD

GND

OGND

OVDD

D7

D6

D0 D1 D2 D3 A/B

D4 D5

Pin Configuration

Ordering Information

19-2835; Rev 2; 7/09

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,or visit Maxim’s website at www.maxim-ic.com.

PART TEMP RANGE PIN-PACKAGE

MAX1192ETI-T -40°C to +85°C 28 Thin QFN-EP*

-Denotes a package containing lead(Pb).*EP = Exposed paddle.T = Tape and reel.

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2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS(VDD = 3.0V, OVDD = 1.8V, VREFIN = VDD (internal reference), CL ≈ 10pF at digital outputs, fCLK = 22MHz, CREFP = CREFN = CCOM =0.33µF, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functionaloperation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure toabsolute maximum rating conditions for extended periods may affect device reliability.

VDD, OVDD to GND ...............................................-0.3V to +3.6VOGND to GND.......................................................-0.3V to +0.3VINA+, INA-, INB+, INB- to GND .................-0.3V to (VDD + 0.3V)CLK, REFIN, REFP, REFN, COM to GND...-0.3V to (VDD + 0.3V)PD0, PD1 to OGND .................................-0.3V to (OVDD + 0.3V)Digital Outputs to OGND.........................-0.3V to (OVDD + 0.3V)Continuous Power Dissipation (TA = +70°C)

28-Pin Thin QFN (derated 20.8mW/°C above +70°C) ..1667mW

Operating Temperature Range ...........................-40°C to +85°CJunction Temperature ......................................................+150°CStorage Temperature Range ............................-65°C to +150°CLead Temperature (soldering, 10s) .................................+300°C

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

DC ACCURACY

Resolution 8 Bits

Integral Nonlinearity INL ±0.15 ±1.00 LSB

Differential Nonlinearity DNL No missing codes over temperature ±0.14 ±1.00 LSB

≥ +25°C ±4Offset Error

< +25°C ±6%FS

Gain Error Excludes REFP - REFN error ±2 %FS

DC Gain Matching ±0.01 ±0.2 dB

Gain Temperature Coefficient ±30 ppm/°C

Offset (VDD ±5%) ±0.02Power-Supply Rejection

Gain (VDD ±5%) ±0.05LSB

ANALOG INPUT

Differential Input Voltage Range VDIFF Differential or single-ended inputs ±0.512 V

Common-Mode Input VoltageRange

VCOM VDD / 2 V

Input Resistance RIN Switched capacitor load 245 kΩInput Capacitance CIN 5 pF

CONVERSION RATE

Clock Frequency Range fCLK 7.5 22 MHz

Channel A 5.0Data Latency

Channel B 5.5Clockcycles

DYNAMIC CHARACTERISTICS (differential inputs, 4096-point FFT)

fIN = 1.875MHz 48.6

fIN = 5.5MHz 47 48.6Signal-to-Noise Ratio(Note 2)

SNR

fIN = 11MHz 48.6

dB

fIN = 1.875MHz 48.7

fIN = 5.5MHz 47 48.6Signal-to-Noise and Distortion(Note 2)

SINAD

fIN = 11MHz 48.6

dB

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ELECTRICAL CHARACTERISTICS (continued)(VDD = 3.0V, OVDD = 1.8V, VREFIN = VDD (internal reference), CL ≈ 10pF at digital outputs, fCLK = 22MHz, CREFP = CREFN = CCOM =0.33µF, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)


fIN = 1.875MHz 70.8

fIN = 5.5MHz 59.0 70.0Spurious-Free Dynamic Range(Note 2)

SFDR

fIN = 11MHz 70.4

dBc

fIN = 1.875MHz 75.8

fIN = 5.5MHz -74.0Thi r d - H ar m oni c D i stor ti on( N ote 2)

HD3

fIN = 11MHz -74.8

dBc

Intermodulation Distortion IMDfIN1 = 1MHz at -7dB FS, fIN2 = 1.01MHz at-7dB FS

-64 dBc

Third-Order Intermodulation IM3fIN1 = 1MHz at -7dB FS, fIN2 = 1.01MHz at-7dB FS

-67 dBc

fIN = 1.875MHz -71.0

fIN = 5.5MHz -70.0 -57.0Total Harmonic Distortion(Note 2)

THD

fIN = 11MHz -70.2

dBc

Small-Signal Bandwidth SSBW Input at -20dB FS 440 MHz

Full-Power Bandwidth FPBW Input at -0.5dB FS 440 MHz

Aperture Delay tAD 1.5 ns

Aperture Jitter tAJ 2 psRMS

Overdrive Recovery Time 1.5 × full-scale input 2 ns

INTERNAL REFERENCE (REFIN = VDD; VREFP, VREFN, and VCOM are generated internally)

REFP Output Voltage VREFP - VCOM 0.256 V

REFN Output Voltage VREFN - VCOM -0.256 V

COM Output Voltage VCOMVDD / 2- 0.15

VDD / 2VDD / 2+ 0.15

V

Differential Reference Output VREF VREFP - VREFN 0.512 V

Differential Reference OutputTemperature Coefficient

VREFTC ±30 ppm/°C

Maximum REFP/REFN/COMSource Current

ISOURCE 2 mA

Maximum REFP/REFN/COM SinkCurrent

ISINK 2 mA

BUFFERED EXTERNAL REFERENCE (VREFIN = 1.024V, VREFP, VREFN, and VCOM are generated internally)

REFIN Input Voltage VREFIN 1.024 V

COM Output Voltage VCOMVDD / 2- 0.15

VDD / 2VDD / 2+ 0.15

V

Differential Reference Output VREF VREFP - VREFN 0.512 V

Maximum REFP/REFN/COMSource Current

ISOURCE 2 mA


Maximum REFP/REFN/COM SinkCurrent

ISINK 2 mA

REFIN Input Resistance >500 kΩREFIN Input Current -0.7 µA

UNBUFFERED EXTERNAL REFERENCE (REFIN = GND, VREFP, VREFN, and VCOM are applied externally)

REFP Input Voltage VREFP - VCOM 0.256 V

REFN Input Voltage VREFN - VCOM -0.256 V

COM Input Voltage VCOM VDD / 2 V

Differential Reference InputVoltage

VREF VREFP - VREFN 0.512 V

REFP Input Resistance RREFP Measured between REFP and COM 4 kΩREFN Input Resistance RREFN Measured between REFN and COM 4 kΩDIGITAL INPUTS (CLK, PD0, PD1)

CLK0.7 xVDD

Input High Threshold VIH

PD0, PD10.7 xOVDD

V

CLK0.3 xVDD

Input Low Threshold VIL

PD0, PD10.3 xOVDD

V

Input Hysteresis VHYST 0.1 V

CLK at GND or VDD ±5Digital Input Leakage Current DIIN

PD0 and PD1 at OGND or OVDD ±5µA

Digital Input Capacitance DCIN 5 pF

DIGITAL OUTPUTS (D7–D0, A/B)

Output Voltage Low VOL ISINK = 200µA0.2 xOVDD

V

Output Voltage High VOH ISOURCE = 200µA0.8 xOVDD

V

Tri-State Leakage Current ILEAK ±5 µA

Tri-State Output Capacitance COUT 5 pF

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4 _______________________________________________________________________________________


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POWER REQUIREMENTS

Analog Supply Voltage VDD 2.7 3.0 3.6 V

Digital Output Supply Voltage OVDD 1.8 VDD V

Normal operating mode, fIN = 1.875MHzat -0.5dB FS, fCLK = 7.5MHz,CLK input from GND to VDD

4.2 5.0

Normal operating mode, fIN = 5.5MHzat -0.5dB FS, fCLK = 22MHz,CLK input from GND to VDD

9.1 10.5

Idle mode (tri-state), fIN = 1.875MHz at -0.5dB FS, fCLK = 7.5MHz, CLK input fromGND to VDD

4.2

Idle mode (tri-state), fIN = 5.5MHz at-0.5dB FS, fCLK = 22MHz, CLK input fromGND to VDD

9.1

Standby mode, fCLK = 7.5MHz, CLK inputfrom GND to VDD

2.3

Standby mode, fCLK = 22MHz, CLK inputfrom GND to VDD

4.9

mA

Analog Supply Current IDD

Shutdown mode, CLK = GND or VDD,PD0 = PD1 = OGND

0.6 5.0 µA

Normal operating mode,fIN = 1.875MHz at -0.5dB FS,fCLK = 7.5MHz, CL ≈ 10pF

1.0

Normal operating mode,fIN = 5.5MHz at -0.5dB FS,fCLK = 22MHz, CL ≈ 10pF

2.9

mA

Idle mode (tri-state), DC input,CLK = GND or VDD,PD0 = OVDD, PD1 = OGND

0.1 5.0

Standby mode, DC input, CLK = GND orVDD, PD0 = OGND, PD1 = OVDD

0.1

Digital Output Supply Current(Note 3)

IODD

Shutdown mode, CLK = GND or VDD,PD0 = PD1 = OGND

0.1 5.0

µA



_______________________________________________________________________________________ 5

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6 _______________________________________________________________________________________


Note 1: Specifications ≥+25°C guaranteed by production test, <+25°C guaranteed by design and characterization.Note 2: SNR, SINAD, SFDR, HD3, and THD are based on a differential analog input voltage of -0.5dB FS referenced to the

amplitude of the digital output. SNR and THD are calculated using HD2 through HD6.Note 3: The power consumption of the output driver is proportional to the load capacitance (CL).Note 4: Guaranteed by design and characterization. Not production tested.Note 5: SINAD settles to within 0.5dB of its typical value.Note 6: Crosstalk rejection is measured by applying a high-frequency test tone to one channel and a low-frequency tone to the

second channel. FFTs are performed on each channel. The parameter is specified as the power ratio of the first and secondchannel FFT test tone bins.

Note 7: Amplitude/phase matching is measured by applying the same signal to each channel, and comparing the magnitude andphase of the fundamental bin on the calculated FFT.


TIMING CHARACTERISTICS

CLK Rise to CHA Output DataValid

tDOA50% of C LK to 50% of d ata,Fi g ur e 5 ( N ote 4)

1 6 8.5 ns

CLK Fall to CHB Output DataValid

tDOB50% of C LK to 50% of d ata,Fi g ur e 5 ( N ote 4)

1 6 8.5 ns

CLK Rise/Fall to A/B Rise/FallTime

tDA/B50% of C LK to 50% of A/B,Fi g ur e 5 ( N ote 4)

1 6 8.5 ns

PD1 Rise to Output Enable tEN PD0 = OVDD 5 ns

PD1 Fall to Output Disable tDIS PD0 = OVDD 5 ns

CLK Duty Cycle 50 %

CLK Duty Cycle Variation ±10 %

Wake-Up Time from ShutdownMode

tWAKE, SD (Note 5) 20 µs

Wake-Up Time from StandbyMode

tWAKE, ST (Note 5) 5.4 µs

Digital Output Rise/Fall Time 20% to 80% 2 ns

INTERCHANNEL CHARACTERISTICS

Crosstalk RejectionfIN,X = 5.5MHz at -0.5dB FS,fIN,Y = 0.3MHz at -0.5dB FS (Note 6)

-75 dB

Amplitude Matching fIN = 5.5MHz at -0.5dB FS (Note 7) ±0.03 dB

Phase Matching fIN = 5.5MHz at -0.5dB FS (Note 7) ±0.1 Degrees

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FFT PLOT CHANNEL A (DIFFERENTIAL INPUTS, 8192-POINT DATA RECORD)

MAX

1192

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1

ANALOG INPUT FREQUENCY (MHz)

AMPL

ITUD

E (d

B)

108642

-80

-70

-60

-50

-40

-30

-20

-10

0

-900 12

fCLK = 22.005678MHzfINA = 5.606183MHzfINB = 8.056034MHzAINA = AINB = -0.5dB FS

HD3 HD2fINB

FFT PLOT CHANNEL B (DIFFERENTIAL INPUTS, 8192-POINT DATA RECORD)

MAX

1192

toc0

2


AMPL

ITUD

E (d

B)

108642

-80

-70

-60

-50

-40

-30

-20

-10

0

-900 12


HD3 HD2fINA

FFT PLOT CHANNEL A (DIFFERENTIAL INPUTS, 8192-POINT DATA RECORD)

MAX

1192

toc0

3


AMPL

ITUD

E (d

B)

108642

-80

-70

-60

-50

-40

-30

-20

-10

0

-900 12


HD3 HD2fINB

FFT PLOT CHANNEL B (DIFFERENTIAL INPUTS, 8192-POINT DATA RECORD)

MAX

1192

toc0

4


AMPL

ITUD

E (d

B)

108642

-80

-70

-60

-50

-40

-30

-20

-10

0

-900 12


HD3 HD2fINA

TWO-TONE IMD PLOT (DIFFERENTIALINPUTS, 8192-POINT DATA RECORD)

MAX

1192

toc0

5


AMPL

ITUD

E (d

B)

108642

-80

-70

-60

-50

-40

-30

-20

-10

0

-900 12

fCLK = 22.005678MHzfIN1 = 1.8MHzfIN2 = 2.3MHzAIN = -7dB FS

fIN2fIN1

Typical Operating Characteristics(VDD = 3.0V, OVDD = 1.8V, VREFIN = VDD (internal reference), CL ≈ 10pF at digital outputs, differential input at -0.5dB FS, fCLK =22.005678MHz at 50% duty cycle, TA = +25°C, unless otherwise noted.)

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FFT PLOT CHANNEL A (SINGLE-ENDED INPUTS, 8192-POINT DATA RECORD)

MAX

1192

toc0

6


AMPL

ITUD

E (d

B)

108642

-80

-70

-60

-50

-40

-30

-20

-10

0

-900 12


HD3 HD2fINB

FFT PLOT CHANNEL B (SINGLE-ENDED INPUTS, 8192-POINT DATA RECORD)

MAX

1192

toc0

7


AMPL

ITUD

E (d

B)

108642

-80

-70

-60

-50

-40

-30

-20

-10

0

-900 12


HD3 HD2fINA

FFT PLOT CHANNEL B (SINGLE-ENDED INPUTS, 8192-POINT DATA RECORD)

MAX

1192

toc0

9


AMPL

ITUD

E (d

B)

108642

-80

-70

-60

-50

-40

-30

-20

-10

0

-900 12


HD3 HD2fINA

FFT PLOT CHANNEL A (SINGLE-ENDED INPUTS, 8192-POINT DATA RECORD)

MAX

1192

toc0

8


AMPL

ITUD

E (d

B)

108642

-80

-70

-60

-50

-40

-30

-20

-10

0

-900 12


HD3 HD2fINB

Typical Operating Characteristics (continued)(VDD = 3.0V, OVDD = 1.8V, VREFIN = VDD (internal reference), CL ≈ 10pF at digital outputs, differential input at -0.5dB FS, fCLK =22.005678MHz at 50% duty cycle, TA = +25°C, unless otherwise noted.)

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_______________________________________________________________________________________ 9

SIGNAL-TO-NOISE RATIOvs. ANALOG INPUT FREQUENCY

MAX

1192

toc1

0


SNR

(dB)

1007525 50

46.5

47.0

47.5

48.0

48.5

49.0

49.5

50.0

46.00 125

CHANNEL A

CHANNEL B

SIGNAL-TO-NOISE AND DISTORTIONvs. ANALOG INPUT FREQUENCY

MAX

1192

toc1

1


SINA

D (d

B)

1007525 50

46.5

47.0

47.5

48.0

48.5

49.0

49.5

50.0

46.00 125

CHANNEL A

CHANNEL B

TOTAL HARMONIC DISTORTIONvs. ANALOG INPUT FREQUENCY

MAX

1192

toc1

2


THD

(dBc

)

1007525 50

-80

-75

-70

-65

-60

-55

-50

-45

-850 125

CHANNEL A

CHANNEL B

SPURIOUS-FREE DYNAMIC RANGEvs. ANALOG INPUT FREQUENCY

MAX

1192

toc1

3


SFDR

(dBc

)

1007525 50

50

55

60

65

70

75

80

85

450 125

CHANNEL A

CHANNEL B


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10 ______________________________________________________________________________________

SPURIOUS-FREE DYNAMIC RANGEvs. ANALOG INPUT POWER

MAX

1192

toc1

7

ANALOG INPUT POWER (dB FS)

SFDR

(dBc

)

-5-10-15-20-25

40

50

60

70

80

30-30 0

fIN = 5.512345MHz


SIGNAL-TO-NOISE RATIOvs. ANALOG INPUT POWER

MAX

1192

toc1

4


SNR

(dB)

-5-10-15-20-25

10

20

30

40

50

60

0-30 0

fIN = 5.512345MHz

SIGNAL-TO-NOISE AND DISTORTIONvs. ANALOG INPUT POWER

MAX

1192

toc1

5


SINA

D (d

B)

-5-10-15-20-25

10

20

30

40

50

60

0-30 0

fIN = 5.512345MHz

TOTAL HARMONIC DISTORTIONvs. ANALOG INPUT POWER

MAX

1192

toc1

6


THD

(dBc

)

-5-10-15-20-25

-70

-60

-50

-40

-30

-80-30 0

fIN = 5.512345MHz

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______________________________________________________________________________________ 11

SPURIOUS-FREE DYNAMIC RANGEvs. SAMPLING RATE

MAX

1192

toc2

1

fCLK (MHz)

SFDR

(dBc

)

5040302010

55

60

65

70

75

80

500 60

fIN = 5.512345MHz


SIGNAL-TO-NOISE RATIOvs. SAMPLING RATE

MAX

1192

toc1

8

fCLK (MHz)

SNR

(dB)

5040302010

46

47

48

49

50

450 60

fIN = 5.512345MHz

SIGNAL-TO-NOISE AND DISTORTIONvs. SAMPLING RATE

MAX

1192

toc1

9

fCLK (MHz)

SINA

D (d

B)

5040302010

46

47

48

49

50

450 60

fIN = 5.512345MHz

TOTAL HARMONIC DISTORTIONvs. SAMPLING RATE

MAX

1192

toc2

0

fCLK (MHz)

THD

(dBc

)

5040302010

-75

-70

-65

-60

-55

-50

-800 60

fIN = 5.512345MHz

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12 ______________________________________________________________________________________

SPURIOUS-FREE DYNAMIC RANGEvs. CLOCK DUTY CYCLE

MAX

1192

toc2

5

CLOCK DUTY CYCLE (%)

SFDR

(dBc

)

555045

62

64

66

68

70

72

74

76

78

80

6040 60

fIN = 5.512345MHz


SIGNAL-TO-NOISE RATIOvs. CLOCK DUTY CYCLE

MAX

1192

toc2

2


SNR

(dB)

555045

46

47

48

49

50

4540 60

fIN = 5.512345MHz

SIGNAL-TO-NOISE AND DISTORTIONvs. CLOCK DUTY CYCLE

MAX

1192

toc2

3


SINA

D (d

B)555045

46

47

48

49

50

4540 60

fIN = 5.512345MHz

TOTAL HARMONIC DISTORTIONvs. CLOCK DUTY CYCLE

MAX

1192

toc2

4


THD

(dBc

)

555045

-78

-76

-74

-72

-70

-68

-66

-64

-62

-60

-8040 60

fIN = 5.512345MHz

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______________________________________________________________________________________ 13

GAIN ERRORvs. TEMPERATURE

MAX

1192

toc2

9

TEMPERATURE (°C)

GAIN

ERR

OR (%

FS)

6035-15 10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

0.10-40 85

VREFIN = 1.024V

CHANNEL A

CHANNEL B

6

-101 100 1000

INPUT BANDWIDTHvs. ANALOG INPUT FREQUENCY

-6

-8

-4

-2

0

2

4

MAX

1192

toc3

0


GAIN

(dB)

10

FULL-POWERBANDWIDTH-0.5dB FS

SMALL-SIGNALBANDWIDTH-20dB FS

REFERENCE VOLTAGEvs. ANALOG SUPPLY VOLTAGE

MAX

1192

toc3

1

VDD (V)

V REF

P - V

REFN

(V)

3.53.43.33.23.13.02.92.8

0.5105

0.5110

0.5115

0.5120

0.5125

0.5130

0.51002.7 3.6

VDD = VREFIN

REFERENCE VOLTAGEvs. TEMPERATURE

MAX

1192

toc3

2

TEMPERATURE (°C)

V REF

P - V

REFN

(V)

603510-15

0.5105

0.5110

0.5115

0.5120

0.5125

0.5130

0.5100-40 85

VDD = VREFIN


INTEGRAL NONLINEARITY

MAX

1192

toc2

6

DIGITAL OUTPUT CODE

INL

(LSB

)

224192128 16064 9632

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

-0.50 256

DIFFERENTIAL NONLINEARITY

MAX

1192

toc2

7

DIGITAL OUTPUT CODE

DNL

(LSB

)

224192128 16064 9632

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

-0.50 256

OFFSET ERROR vs. TEMPERATURE

MAX

1192

toc2

8

TEMPERATURE (°C)

OFFS

ET E

RROR

(% F

S)

603510-15

-0.59

-0.58

-0.57

-0.56

-0.55

-0.54

-0.53

-0.52

-0.51

-0.50

-0.60-40 85

VREFIN = 1.024V

CHANNEL A

CHANNEL B

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14 ______________________________________________________________________________________

SUPPLY CURRENTvs. INPUT FREQUENCY

MAX1192 toc33

fIN (MHz)

DIGI

TAL

SUPP

LY C

URRE

NT (m

A)

108642

0.5

1.0

1.5

2.0

2.5

3.0

0

ANAL

OG S

UPPL

Y CU

RREN

T (m

A)

8.8

9.0

9.2

9.4

9.6

9.8

8.60 12

DIGITAL SUPPLY CURRENT

ANALOG SUPPLY CURRENT

SUPPLY CURRENTvs. SAMPLING RATE

MAX

1192

toc3

4

fCLK (MHz)SU

PPLY

CUR

RENT

(mA)

5030 402010

A: ANALOG SUPPLY CURRENT (IDD) - INTERNAL AND BUFFERED EXTERNAL REFERENCE MODESB: ANALOG SUPPLY CURRENT (IDD) - UNBUFFERED EXTERNAL REFERENCE MODEC: DIGITAL SUPPLY CURRENT (IODD) - ALL REFERENCE MODES

5

10

15

20

25

00 60

A

B

C

fIN = 5.5112345MHz

Pin DescriptionPIN NAME FUNCTION

1 INA- Channel A Negative Analog Input. For single-ended operation, connect INA- to COM.

2 INA+ Channel A Positive Analog Input. For single-ended operation, connect signal source to INA+.

3, 5, 10 GND Analog Ground. Connect all GND pins together.

4 CLK Converter Clock Input

6 INB+ Channel B Positive Analog Input. For single-ended operation, connect signal source to INB+.

7 INB- Channel B Negative Analog Input. For single-ended operation, connect INB- to COM.

8, 9, 28 VDDConverter Power Input. Connect to a 2.7V to 3.6V power supply. Bypass VDD to GND with acombination of a 2.2µF capacitor in parallel with a 0.1µF capacitor.

11 OGND Output Driver Ground

12 OVDDOutput Driver Power Input. Connect to a 1.8V to VDD power supply. Bypass OVDD to GND with acombination of a 2.2µF capacitor in parallel with a 0.1µF capacitor.

13 D7 Tri-State Digital Output. D7 is the most significant bit (MSB).

14 D6 Tri-State Digital Output



17 A/BChannel Data Indicator. This digital output indicates channel A data (A/B = 1) or channel B data(A/B = 0) is present on the output.




21 D0 Tri-State Digital Output. D0 is the least significant bit (LSB).

22 PD1 Power-Down Digital Input 1. See Table 3.


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Detailed DescriptionThe MAX1192 uses a seven-stage, fully differential,pipelined architecture (Figure 1) that allows for high-speed conversion while minimizing power consump-tion. Samples taken at the inputs move progressivelythrough the pipeline stages every half-clock cycle.Including the delay through the output latch, the totalclock-cycle latency is 5 clock cycles for channel A and5.5 clock cycles for channel B.

At each stage, flash ADCs convert the held input volt-ages into a digital code. The following digital-to-analogconverter (DAC) converts the digitized result back intoan analog voltage, which is then subtracted from theoriginal held input signal. The resulting error signal isthen multiplied by two, and the product is passed alongto the next pipeline stage where the process is repeateduntil the signal has been processed by all stages. Digitalerror correction compensates for ADC comparator off-sets in each pipeline stage and ensures no missingcodes. Figure 2 shows the MAX1192 functional diagram.

Pin Description (continued)PIN NAME FUNCTION

23 PD0 Power-Down Digital Input 0. See Table 3.

24 REFIN Reference Input. Internally pulled up to VDD.

25 COM Common-Mode Voltage I/O. Bypass COM to GND with a 0.33µF capacitor.

26 REFNNegative Reference I/O. Conversion range is ±(VREFP - VREFN). Bypass REFN to GND with a 0.33µFcapacitor.

27 REFPPositive Reference I/O. Conversion range is ±(VREFP - VREFN). Bypass REFP to GND with a 0.33µFcapacitor.

— EP Exposed Paddle. Internally connected to pin 3. Externally connect EP to GND.

INA+

INA-T/H

DIGITAL ERROR CORRECTION

/

D0–D7

FLASHADC

T/H

DAC

∑-

+x2

1.5 BITS

STAGE 1 STAGE 2 STAGE 7

Figure 1. Pipeline Architecture—Stage Blocks

INA+

INA-DEC/T/H

INB+

INB-DEC/T/H /

REFERENCESYSTEM AND

BIASCIRCUITS

PIPELINEADC

A

COM

REFIN

REFN

REFP

CLKTIMING

OVDD

OGND

MULTIPLEXER OUTPUTDRIVERS

POWERCONTROL

D0–D7

/

/

VDD

GND

A/B

PD0PD1

PIPELINEADC

B

MAX1192

Figure 2. MAX1192 Functional Diagram

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16 ______________________________________________________________________________________

Input Track-and-Hold (T/H) CircuitsFigure 3 displays a simplified functional diagram of theinput T/H circuits. In track mode, switches S1, S2a,S2b, S4a, S4b, S5a, and S5b are closed. The fully dif-ferential circuits sample the input signals onto the twocapacitors (C2a and C2b) through switches S4a andS4b. S2a and S2b set the common mode for the ampli-

fier input, and open simultaneously with S1, samplingthe input waveform. Switches S4a, S4b, S5a, and S5bare then opened before switches S3a and S3b connectcapacitors C1a and C1b to the output of the amplifierand switch S4c is closed. The resulting differential volt-ages are held on capacitors C2a and C2b. The ampli-fiers charge capacitors C1a and C1b to the same

S3b

S3a

COM

S5b

S5a

INB+

INB-

S1

OUT

OUT

C2a

C2b

S4c

S4a

S4b

C1b

C1a

INTERNALBIAS

INTERNALBIAS

COM

HOLD HOLDCLK

INTERNALNONOVERLAPPINGCLOCK SIGNALS

TRACK TRACK

S2a

S2b

S3b

S3a

COM

S5b

S5a

INA+

INA-

S1

OUT

OUT

C2a

C2b

S4c

S4a

S4b

C1b

C1a

INTERNALBIAS

INTERNALBIAS

COM

S2a

S2b

MAX1192

Figure 3. Internal T/H Circuits

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______________________________________________________________________________________ 17

values originally held on C2a and C2b. These valuesare then presented to the first stage quantizers and iso-late the pipelines from the fast-changing inputs. Thewide input bandwidth T/H amplifiers allow the MAX1192to track and sample/hold analog inputs of high frequen-cies (>Nyquist). Both ADC inputs (INA+, INB+, INA-,and INB-) can be driven either differentially or singleended. Match the impedance of INA+ and INA-, as wellas INB+ and INB-, and set the common-mode voltageto midsupply (VDD/2) for optimum performance.

Analog Inputs and ReferenceConfigurations

The MAX1192 full-scale analog input range is ±VREFwith a common-mode input range of VDD/2 ±0.2V. VREFis the difference between VREFP and VREFN. TheMAX1192 provides three modes of reference operation.The voltage at REFIN (VREFIN) sets the reference oper-ation mode (Table 1).

In internal reference mode, connect REFIN to VDD orleave REFIN unconnected. VREF is internally generatedto be 0.512V ±3%. COM, REFP, and REFN are low-impedance outputs with VCOM = VDD/2, VREFP = VDD/2+ VREF/2, and VREFN = VDD/2 - VREF/2. Bypass REFP,REFN, and COM each with a 0.33µF capacitor.

In buffered external reference mode, apply a 1.024V±10% at REFIN. In this mode, COM, REFP, and REFNare low-impedance outputs with VCOM = VDD/2, VREFP =VDD/2 + VREFIN/4, and VREFN = VDD/2 - VREFIN/4.Bypass REFP, REFN, and COM each with a 0.33µFcapacitor. Bypass REFIN to GND with a 0.1µF capacitor.

In unbuffered external reference mode, connect REFINto GND. This deactivates the on-chip reference buffersfor COM, REFP, and REFN. With their buffers shutdown, these nodes become high-impedance inputs(Figure 4) and can be driven through separate, externalreference sources. Drive VCOM to VDD/2 ±10%, drive

VREFP to (VDD/2 +0.256V) ±10%, and drive VREFN to(VDD/2 - 0.256V) ±10%. Bypass REFP, REFN, and COMeach with a 0.33µF capacitor.

For detailed circuit suggestions and how to drive thisdual ADC in buffered/unbuffered external referencemode, see the Applications Information section.

Clock Input (CLK)CLK accepts a CMOS-compatible signal level. Sincethe interstage conversion of the device depends on therepeatability of the rising and falling edges of the exter-nal clock, use a clock with low jitter and fast rise andfall times (<2ns). In particular, sampling occurs on therising edge of the clock signal, requiring this edge to

Figure 4. Unbuffered External Reference Mode Impedance

VREFIN REFERENCE MODE

>0.8 x VDDInternal reference mode. VREF is internally generated to be 0.512V. Bypass REFP, REFN, and COMeach with a 0.33µF capacitor.

1.024V ±10%Buffered external reference mode. An external 1.024V ±10% reference voltage is applied toREFIN. VREF is internally generated to be VREFIN/2. Bypass REFP, REFN, and COM each with a0.33µF capacitor. Bypass REFIN to GND with a 0.1µF capacitor.

<0.3VUnbuffered external reference mode. REFP, REFN, and COM are driven by external referencesources. VREF is the difference between the externally applied VREFP and VREFN. Bypass REFP,REFN, and COM each with a 0.33µF capacitor.

Table 1. Reference Modes

MAX1192

1.5V

1.25V

1.75V

62.5μA

0μACOM

REFN

REFP

4kΩ

4kΩ

62.5μA

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18 ______________________________________________________________________________________

provide lowest possible jitter. Any significant aperturejitter would limit the SNR performance of the on-chipADCs as follows:

where fIN represents the analog input frequency andtAJ is the time of the aperture jitter.

Clock jitter is especially critical for undersamplingapplications. The clock input should always be consid-ered as an analog input and routed away from any ana-log input or other digital signal lines. The MAX1192clock input operates with a VDD/2 voltage thresholdand accepts a 50% ±10% duty cycle (see TypicalOperating Characteristics).

System Timing RequirementsFigure 5 shows the relationship between the clock, ana-log inputs, A/B indicator, and the resulting output data.Channel A (CHA) and channel B (CHB) are simultane-ously sampled on the rising edge of the clock signal(CLK) and the resulting data is multiplexed at the out-put. CHA data is updated on the rising edge and CHBdata is updated on the falling edge of the CLK. The A/Bindicator follows CLK with a typical delay time of 6nsand remains high when CHA data is updated and lowwhen CHB data is updated. Including the delaythrough the output latch, the total clock-cycle latency is5 clock cycles for CHA and 5.5 clock cycles for CHB.

Digital Output Data (D0–D7), Channel Data Indicator (A/BB)

D0–D7 and A/B are TTL/CMOS-logic compatible. Thedigital output coding is offset binary (Table 2, Figure 6).The capacitive load on the digital outputs D0–D7should be kept as low as possible (<15pF) to avoidlarge digital currents feeding back into the analog por-tion of the MAX1192 and degrading its dynamic perfor-mance. Buffers on the digital outputs isolate them from

SNRf tIN AJ

log

= ×× × ×

⎛

⎝⎜⎞

⎠⎟20

12 π

tDOB

tCL tCH

tCLK

tDOA

tDA/B

5 CLOCK-CYCLE LATENCY (CHA), 5.5 CLOCK-CYCLE LATENCY (CHB)

A/B CHB

D0–D7 D0B

CHA

D1A

CHB

D1B

CHA

D2A

CHB

D2B

CHA

D3A

CHB

D3B

CHA

D4A

CHB

D4B

CHA

D5A

CHB

D5B

CHA

D6A

CHB

D6B

CHA

CHB

CLK

Figure 5. System Timing Diagram

Figure 6. Transfer Function

INPUT VOLTAGE (LSB)

-1-126 -125

2562 x VREF1LSB = VREF = VREFP - VREFN

VREF VREF

V REF

V REF

0 +1-127 +126 +128+127-128 +125

(COM)

(COM)

OFFS

ET B

INAR

Y OU

TPUT

COD

E (L

SB)

0000 00000000 00010000 00100000 0011

1111 11111111 11101111 1101

0111 11111000 00001000 0001

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______________________________________________________________________________________ 19

heavy capacitive loads. To improve the dynamic perfor-mance of the MAX1192, add 100Ω resistors in serieswith the digital outputs close to the MAX1192. Refer tothe MAX1193 Evaluation Kit schematic for an exampleof the digital outputs driving a digital buffer through100Ω series resistors.

Power Modes (PD0, PD1)The MAX1192 has four power modes that are con-trolled with PD0 and PD1. Four power modes allow theMAX1192 to efficiently use power by transitioning to alow-power state when conversions are not required(Table 3).

Shutdown mode offers the most dramatic power sav-ings by shutting down all the analog sections of theMAX1192 and placing the outputs in tri-state. The

wake-up time from shutdown mode is dominated by thetime required to charge the capacitors at REFP, REFN,and COM. In internal reference mode and bufferedexternal reference mode, the wake-up time is typically20µs. When operating in the unbuffered external refer-ence mode, the wake-up time is dependent on theexternal reference drivers. When the outputs transitionfrom tri-state to on, the last converted word is placedon the digital outputs.

In standby mode, the reference and clock distributioncircuits are powered up, but the pipeline ADCs areunpowered and the outputs are in tri-state. The wake-up time from standby mode is dominated by the 5.4µsrequired to activate the pipeline ADCs. When the out-puts transition from tri-state to on, the last convertedword is placed on the digital outputs.

DIFFERENTIAL INPUT VOLTAGE(IN+ - IN-)

DIFFERENTIAL INPUT(LSB)

OFFSET BINARY(D7–D0)

OUTPUT DECIMAL CODE

+127(+ full scale - 1 LSB)

1111 1111 255

+126(+ full scale - 2 LSB)

1111 1110 254

+1 1000 0001 129

0 (bipolar zero) 1000 0000 128

-1 0111 1111 127

-127(- full scale + 1 LSB)

0000 0001 1

- 128 (- full scale) 0000 0000 0

VREF × 127

128

VREF × 126

128

VREF × 1

128

VREF × 0

128

-VREF × 1

128

-VREF × 127

128

-VREF × 128

128

Table 2. Output Codes vs. Input Voltage

PD0 PD1 POWER MODE ADCINTERNAL

REFERENCECLOCK DISTRIBUTION OUTPUTS

0 0 Shutdown Off Off Off Tri-state

0 1 Standby Off On On Tri-state

1 0 Idle On On On Tri-state

1 1 Normal Operating On On On On

Table 3. Power Logic

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In idle mode, the pipeline ADCs, reference, and clockdistribution circuits are powered, but the outputs areforced to tri-state. The wake-up time from idle mode isdominated by the 5ns required for the output drivers tostart from tri-state. When the outputs transition from tri-state to on, the last converted word is placed on thedigital outputs.

In the normal operating mode, all sections of theMAX1192 are powered.

Applications InformationThe circuit of Figure 7 operates from a single 3V supplyand accommodates a wide 0.5V to 1.5V input common-mode voltage range for the analog interface betweenan RF quadrature demodulator (differential, DC-cou-pled signal source) and a high-speed ADC.Furthermore, the circuit provides required SINAD andSFDR to demodulate a wideband (BW = 3.84MHz),QAM-16 communication link. RISO isolates the op ampoutput from the ADC capacitive input to prevent ringingand oscillation. CIN filters high-frequency noise.

MAX1192

INA+

COM

INA-

AV = 6V/VVCOM = VDD/2

VCOM = 1V TO 1.5VVSIG = ±85mVP-P

�

RISO22Ω

RISO22Ω

R11600Ω

R9600Ω

R2300Ω

OPERATIONAL AMPLIFIERSCHOOSE EITHER OF THE MAX4452/MAX4453/MAX4454 SINGLE/DUAL/QUAD +3V, 200MHz OP AMPS FOR USE WITH THIS CIRCUIT.CONNECT THE POSITIVE SUPPLY RAIL (VCC) TO 3V. CONNECT THE NEGATIVE SUPPLY RAIL (VEE) TO GROUND. DECOUPLE VCC WITH A0.1μF CAPACITOR TO GROUND.

RESISTOR NETWORKSRESISTOR NETWORKS ENSURE PROPER THERMAL AND TOLERANCEMATCHING. FOR R1, R2, AND R3 USE A NETWORK SUCH AS VISHAY'S 3R MODEL NUMBER 300192. FOR R4–R11, USE A NETWORK SUCH AS VISHAY'S 4R MODEL NUMBER 300197.

R10600Ω

R8600Ω

R5600Ω

R4600Ω

R7600Ω

R6600Ω

CIN5pF

CIN5pF

�

R1600Ω

R3600Ω

Figure 7. DC-Coupled Differential Input Driver

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______________________________________________________________________________________ 21

Using Transformer CouplingAn RF transformer (Figure 8) provides an excellentsolution to convert a single-ended source signal to afully differential signal, required by the MAX1192 foroptimum performance. Connecting the center tap of thetransformer to COM provides a VDD/2 DC level shift tothe input. Although a 1:1 transformer is shown, a step-up transformer can be selected to reduce the driverequirements. A reduced signal swing from the inputdriver, such as an op amp, can also improve the overalldistortion.

In general, the MAX1192 provides better SFDR andTHD with fully differential input signals than single-ended drive, especially for high input frequencies. Indifferential input mode, even-order harmonics are loweras both inputs (INA+, INA- and/or INB+, INB-) are bal-

anced, and each of the ADC inputs only requires halfthe signal swing compared to single-ended mode.

Single-Ended AC-Coupled Input SignalFigure 9 shows an AC-coupled, single-ended applica-tion. Amplifiers such as the MAX4108 provide highspeed, high bandwidth, low noise, and low distortion tomaintain the input signal integrity.

Buffered External Reference DrivesMultiple ADCs

The buffered external reference mode allows for morecontrol over the MAX1192 reference voltage and allowsmultiple converters to use a common reference. Todrive one MAX1192 in buffered external referencemode, the external circuit must sink 0.7µA, allowing onereference circuit to easily drive the REFIN of multipleconverters to 1.024V ±10%.

MAX1192

T1

N.C.

VIN61

52

43

22pF

22pF

0.1μF

0.1μF

2.2μF

25Ω

25Ω

MINICIRCUITSTT1-6-KK81

T1

N.C.

VIN61

52

43

22pF

22pF

0.1μF

0.1μF

2.2μF

25Ω

25Ω

MINICIRCUITSTT1-6-KK81

INA-

INA+

INB-

INB+

COM

Figure 8. Transformer-Coupled Input Drive

MAX1192

0.1μF

1kΩ

1kΩ100Ω

100Ω

CIN22pF

CIN22pF

INB+

INB-

COM

INA+

INA-

0.1μFRISO50Ω

RISO50Ω

REFP

REFN

VIN

MAX4108

0.1μF

1kΩ

1kΩ100Ω

100Ω

CIN22pF

CIN22pF

0.1μFRISO50Ω

RISO50Ω

REFP

REFN

VIN

MAX4108

Figure 9. Using an Op Amp for Single-Ended, AC-CoupledInput Drive

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22 ______________________________________________________________________________________

Figure 10 shows the MAX6061 precision bandgap ref-erence used as a common reference for multiple con-verters. The 1.248V output of the MAX6061 is divideddown to 1.023V as it passes through a one-pole, 10Hz,lowpass filter to the MAX4250. The MAX4250 buffersthe 1.023V reference before its output is applied to theMAX1192. The MAX4250 provides a low offset voltage(for high gain accuracy) and a low noise level.

Unbuffered External Reference DrivesMultiple ADCs

The unbuffered external reference mode allows for pre-cise control over the MAX1192 reference and allowsmultiple converters to use a common reference.Connecting REFIN to GND disables the internal refer-ence, allowing REFP, REFN, and COM to be drivendirectly by a set of external reference sources.

MAX4250

3V

2

4

2

1.248V

3 5

10Hz LOWPASS

FILTER

1 15Ω

1REFIN

VDD

MAX1192

N = 1

24

GND

1.023VNOTE: ONE FRONT-END REFERENCE CIRCUIT PROVIDES ±15mA OF OUTPUT DRIVE AND SUPPORTS OVER 1000 MAX1192s.

3

0.1μF

0.1μF

3V

1μF

1%20kΩ

1%90.9kΩ

0.1μF 2.2μF

0.1μF

REFP27

0.33μF

REFN26

0.33μF

COM25

0.33μF

REFINVDD

MAX1192

N = 1000

24

GND

0.1μF

REFP27

0.33μF

REFN26

0.33μF

COM25

0.33μF

MAX6061

Figure 10. External Buffered (MAX4250) Reference Drive Using a MAX6062 Bandgap Reference

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Figure 11 shows the MAX6066 precision bandgap ref-erence used as a common reference for multiple con-verters. The 2.500V output of the MAX6066 is followedby a 10Hz lowpass filter and precision voltage-divider.The MAX4254 buffers the taps of this divider to providethe 1.75V, 1.5V, and 1.25V sources to drive REFP,REFN, and COM. The MAX4254 provides a low offsetvoltage and low noise level. The individual voltage fol-lowers are connected to 10Hz lowpass filters, which fil-ter both the reference-voltage and amplifier noise to alevel of 3nV/√Hz. The 1.75V and 1.25V reference volt-

ages set the differential full-scale range of the associat-ed ADCs at ±0.5V.

The common power supply for all active componentsremoves any concern regarding power-supplysequencing when powering up or down.

With the outputs of the MAX4252 matching better than0.1%, the buffers and subsequent lowpass filters sup-port as many as 160 MAX1192s.

MAX4254

1/4 47Ω

3V

2

2

2.500V

3

1

1

REFPVDD

MAX1192

N = 1

27

GNDNOTE: ONE FRONT-ENDREFERENCE CIRCUIT SUPPORTS UP TO 160 MAX1192s

3

0.1μF

10μF6V1μF

1%30.1kΩ

1%10.0kΩ

0.1μF 2.2μF

330μF6V

0.33μF

26 24

0.33μFREFN REFIN

REFIN

25

0.33μFCOM

MAX6066

1.748V

1%10.0kΩ

1%49.9kΩ

REFPVDD

MAX1192

N = 160

27

GND

0.33μF

26 24

0.33μFREFN

25

0.33μFCOM

1.47kΩ

MAX4254

47Ω

6

5

7

10μF6V

330μF6V

1.498V

1.47kΩ

47Ω

9

10

8

10μF6V

330μF6V

1.248V

MAX4254

1.47kΩ

1MΩ MAX425413

12

14

11

40.1μF

UNCOMMITTED1MΩ

3V

1/4

1/41/4

Figure 11. External Unbuffered Reference Driving 160 ADCs with MAX4254 and MAX6066

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24 ______________________________________________________________________________________

Typical QAM Demodulation ApplicationQuadrature amplitude modulation (QAM) is frequentlyused in digital communications. Typically found inspread-spectrum-based systems, a QAM signal repre-sents a carrier frequency modulated in both amplitudeand phase. At the transmitter, modulating the basebandsignal with quadrature outputs, a local oscillator fol-lowed by subsequent upconversion can generate theQAM signal. The result is an in-phase (I) and a quadra-ture (Q) carrier component, where the Q component is90° phase shifted with respect to the in-phase compo-nent. At the receiver, the QAM signal is demodulatedinto analog I and Q components. Figure 12 displays thedemodulation process performed in the analog domainusing the MAX1192 dual-matched, 3V, 8-bit ADC andthe MAX2451 quadrature demodulator to recover anddigitize the I and Q baseband signals. Before being dig-itized by the MAX1192, the mixed-down signal compo-nents can be filtered by matched analog filters, such asNyquist or pulse-shaping filters. The filters removeunwanted images from the mixing process, therebyenhancing the overall signal-to-noise (SNR) perfor-mance and minimizing intersymbol interference.

Grounding, Bypassing,and Board Layout

The MAX1192 requires high-speed board layout designtechniques. Refer to the MAX1193 Evaluation Kit datasheet for a board layout reference. Locate all bypasscapacitors as close to the device as possible, prefer-

ably on the same side as the ADC, using surface-mount devices for minimum inductance. Bypass VDD toGND with a 0.1µF ceramic capacitor in parallel with a2.2µF bipolar capacitor. Bypass OVDD to OGND with a0.1µF ceramic capacitor in parallel with a 2.2µF bipolarcapacitor. Bypass REFP, REFN, and COM each toGND with a 0.33µF ceramic capacitor.

Multilayer boards with separated ground and powerplanes produce the highest level of signal integrity. Usea split ground plane arranged to match the physicallocation of the analog ground (GND) and the digitaloutput driver ground (OGND) on the ADC’s package.Connect the MAX1192 exposed backside paddle toGND. Join the two ground planes at a single point suchthat the noisy digital ground currents do not interferewith the analog ground plane. The ideal location of thisconnection can be determined experimentally at apoint along the gap between the two ground planes,which produces optimum results. Make this connectionwith a low-value, surface-mount resistor (1Ω to 5Ω), aferrite bead, or a direct short. Alternatively, all groundpins could share the same ground plane, if the groundplane is sufficiently isolated from any noisy, digital sys-tems ground plane (e.g., downstream output buffer orDSP ground plane).

Route high-speed digital signal traces away from thesensitive analog traces of either channel. Make sure toisolate the analog input lines to each respective con-verter to minimize channel-to-channel crosstalk. Keepall signal lines short and free of 90° turns.

0°90°

÷8

DOWNCONVERTER

MAX2451 INA+

MAX1192

INA-

INB+INB-

DSP POST-

PROCESSING

A/B

Figure 12. Typical QAM Receiver Application

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Static Parameter DefinitionsIntegral Nonlinearity (INL)

Integral nonlinearity is the deviation of the values on anactual transfer function from a straight line. This straightline can be either a best-straight-line fit or a line drawnbetween the end points of the transfer function, onceoffset and gain errors have been nullified. The static lin-earity parameters for the MAX1192 are measured usingthe end-point method.

Differential Nonlinearity (DNL)Differential nonlinearity is the difference between anactual step width and the ideal value of 1LSB. A DNLerror specification of less than 1LSB guarantees nomissing codes and a monotonic transfer function.

Offset ErrorIdeally, the midscale MAX1192 transition occurs at 0.5LSB above midscale. The offset error is the amount ofdeviation between the measured transition point andthe ideal transition point.

Gain ErrorIdeally, the full-scale MAX1192 transition occurs at 1.5LSB below full-scale. The gain error is the amount ofdeviation between the measured transition point andthe ideal transition point with the offset error removed.

Dynamic Parameter DefinitionsAperture Jitter

Figure 13 depicts the aperture jitter (tAJ), which is thesample-to-sample variation in the aperture delay.

Aperture DelayAperture delay (tAD) is the time defined between therising edge of the sampling clock and the instant whenan actual sample is taken (Figure 13).

Signal-to-Noise Ratio (SNR)For a waveform perfectly reconstructed from digitalsamples, the theoretical maximum SNR is the ratio ofthe full-scale analog input (RMS value) to the RMSquantization error (residual error). The ideal, theoreticalminimum analog-to-digital noise is caused by quantiza-tion error only and results directly from the ADC’s reso-lution (N bits):

SNRdB[max] = 6.02 × N + 1.76

In reality, there are other noise sources besides quanti-zation noise: thermal noise, reference noise, clock jitter,etc. SNR is computed by taking the ratio of the RMSsignal to the RMS noise. RMS noise includes all spec-tral components to the Nyquist frequency excluding thefundamental, the first five harmonics, and the DC offset.

Signal-to-Noise Plus Distortion (SINAD)SINAD is computed by taking the ratio of the RMS sig-nal to the RMS noise. RMS noise includes all spectralcomponents to the Nyquist frequency excluding thethe fundamental and the DC offset.

Effective Number of Bits (ENOB)ENOB specifies the dynamic performance of an ADC ata specific input frequency and sampling rate. An idealADC’s error consists of quantization noise only. ENOBfor a full-scale sinusoidal input waveform is computedfrom:

ENOBSINAD

.

.= - 1 76

6 02

HOLD

ANALOGINPUT

SAMPLEDDATA (T/H)

T/H

tADtAJ

TRACK TRACK

CLK

Figure 13. T/H Aperture Timing

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Total Harmonic Distortion (THD)THD is typically the ratio of the RMS sum of the first fiveharmonics of the input signal to the fundamental itself.This is expressed as:

where V1 is the fundamental amplitude, and V2–V6 arethe amplitudes of the 2nd- through 6th-order harmonics.

Third Harmonic Distortion (HD3)HD3 is defined as the ratio of the RMS value of the thirdharmonic component to the fundamental input signal.

Spurious-Free Dynamic Range (SFDR)SFDR is the ratio expressed in decibels of the RMSamplitude of the fundamental (maximum signal compo-nent) to the RMS value of the next largest spuriouscomponent, excluding DC offset.

Intermodulation Distortion (IMD)IMD is the total power of the intermodulation productsrelative to the total input power when two tones, f1 andf2, are present at the inputs. The intermodulation prod-ucts are (f1 ±f2), (2 x f1), (2 x f2), (2 x f1 ±f2), (2 x f2±f1). The individual input tone levels are at -7dB FS.

Third-Order Intermodulation (IM3)IM3 is the power of the worst third-order intermodula-tion product relative to the input power of either inputtone when two tones, f1 and f2, are present at theinputs. The third-order intermodulation products are (2x f1 ±f2), (2 x f2 ±f1). The individual input tone levelsare at -7dB FS.

Power-Supply RejectionPower-supply rejection is defined as the shift in offsetand gain error when the power supplies are moved ±5%.

Small-Signal BandwidthA small -20dB FS analog input signal is applied to anADC in such a way that the signal’s slew rate will notlimit the ADC’s performance. The input frequency isthen swept up to the point where the amplitude of thedigitized conversion result has decreased by -3dB.Note that the track/hold (T/H) performance is usuallythe limiting factor for the small-signal input bandwidth.

Full-Power BandwidthA large -0.5dB FS analog input signal is applied to anADC, and the input frequency is swept up to the pointwhere the amplitude of the digitized conversion resulthas decreased by -3dB. This point is defined as full-power input bandwidth frequency.

THDV V V V V

V log

= ×

+ + + +⎡

⎣

⎢⎢⎢

⎤

⎦

⎥⎥⎥

20 22

32

42

52

62

1

Chip InformationPROCESS: CMOS

Package InformationFor the latest package outline information and land patterns, goto www.maxim-ic.com/packages.

PACKAGE TYPE PACKAGE CODE DOCUMENT NO.

10 TQFN-EP T2855-3 21-0140

http://pdfserv.maxim-ic.com/package_dwgs/21-0140

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Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses areimplied. Maxim reserves the right to change the circuitry and specifications without notice at any time.

Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 27

© 2009 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.

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