mmic design and development - sharifee.sharif.edu/~mmic/notes/measurements.pdf · microwave...

MMIC Design and Development

Instructor Dr. Ali Medi

Microwave Measurements

Types of MeasurementsTypes of Measurements

• Swept FrequencySwept Frequency– Power, Gain, Match

Noise Figure– Noise Figure • Single Frequency

– Amplitude and PhaseLinearity• DC

– Input power and efficiency


PowerPower• Standard unit of Power is Watt

– milliwatt is 10-3Watt • dB scale is used to compress the scaledB scale is used to compress the scale

when working over a wide range of power levelpower level– Power in dBW = 10log10(Power in watts)– Power in dBm = 10log (Power in milliwatts)– Power in dBm = 10log10(Power in milliwatts)


Gain or LossGain or Loss

Pin Pout Gain = Pout / PinPin

Or

Gain (dB) = Pout(dB) – Pin(dB)Gain (dB) Pout(dB) Pin(dB)Amplifier

Pin PoutGain = Pout / Pin < 1

Or

Lossy Element

Or

Gain (dB) = Pout(dB) – Pin(dB) < 0


Cascaded ElementsCascaded ElementsPin PoutPin

G1 G2 G3 G4 G5

Pout = Pin*G1*G2*G3*G4*G5 In natural units

Pout = Pin+G1+G2+G3+G4+G5 In dB


Gain RippleGain RippleFrequency Response

20 8

15 6

B)Specified and Measured in

10

Gai

n (d

B)

4

se F

igur

e (d

BSpec ed a d easu edan operating frequency band

5 2

Noi

s

Gain (L)

7 8 9 10 11 12 13 14Frequency(GHz)

0 0Noise Figure (R)


Frequency (GHz)

MatchMatch

• Measure of reflection at an interfaceMeasure of reflection at an interface– Reflections due to mismatch in impedance at

the Input or Output of a devicethe Input or Output of a device• Reflection coefficient ρ

VSWR• VSWR• Return loss


MatchMatchZ0 ZZ0 ZL

If ZL = Z0 If ZL = 0

ρ = ZL – Z0

ZL + Z0

ρ = 0 -1

VSWR =1 + |ρ|1 - |ρ|

VSWR = 1:1: 1 infinite:1

Return Loss = -20 Log10 (|ρ|) Return Loss = -infinite 0dB


S ParametersS Parameters

2 P ta1 a2

2 PortNetworkb1 b2

⎤⎡⎤⎡⎤⎡ 112111 aSSb⎥⎦

⎤⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡=⎥

⎦

⎤⎢⎣

⎡

2

1

2221

1211

2

1

aa

SSSS

bb

⎦⎣⎦⎣⎦⎣ 222212 aSSbExtend to any number of portsn ports is and n x n S matrix


n ports is and n x n S matrix

Interpretation of SijInterpretation of Sij

⎤⎡⎤⎡⎤⎡ 112111 aSSb a1 a2

⎥⎦

⎤⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡=⎥

⎦

⎤⎢⎣

⎡

2

1

2221

1211

2

1

aSSb b1 b2

F t h d l d t 2For matched load on port 2 For matched load on port 1

b02 =a 01 =a

1

111 a

bS =2

112 a

bS =

1

221 a

bS =2

222 a

bS =


1 2

Smith ChartSmith Chart

Microwave Measurementshttp://www.web-ee.com/primers/files/SmithCharts/smith_charts.htm

Smith Chart ExamplesSmith Chart Examples


Noise FigureNoise Figure

• Noise figure is a measure of the amount ofNoise figure is a measure of the amount of noise added by a device

• Measure noise power output of a device• Measure noise power output of a device with the input terminated in a matched load N i Fi i dBload.

)( GNFkTBdBmNPO ++

Noise power output

Noise Figure in dB Gain in dB

)(10114)()(

10 BLogdBmkTBGNFkTBdBmNPO

+−=++=

Microwave Measurements Bandwidth in MHz

System Noise FigureSystem Noise Figurenf1 nf2 nf3 nfN

gain1 gain2 gain3 gainN

nf system =Natural units

NF (dB) = 10Log10(nf)

GAIN (dB) = 10Log10(gain)


GAIN (dB) 10Log10(gain)

Amplitude LinearityAmplitude Linearity1dB

rpu

t Pow

erO

utp

Input Power


Multicarrier EffectsMulticarrier Effects2 pure signals f1 and f2 multiple signals emerge

Nonlinear amplifier

f1 f22f1-f2 f1 f2 2f2-f1

3rd order intermodulation products

Higher order intermodulation products also present


3rd order intercept pointIp3

Single carrierSingle carrier

Power in each of 2 carriers

t Pow

er

o e eac o ca e s

Power in each of 3rd order product

Out

pu

Input Power


P3rd-order = Ptones@output - 2 · (IP3 - Ptones@output) {dBm}

More IP3More IP3

P3rd+3(IP3 P1st)=IP3P3rd+3(IP3-P1st)=IP3

http://www testedgeinc com/docs/ip3 pdf


http://www.testedgeinc.com/docs/ip3.pdf

Noise Power RatioNoise Power Ratio

• Measure of intermodulation products whenMeasure of intermodulation products when many carriers are present

• A measurement is made using a noise• A measurement is made using a noise source and notch filter

Nonlinear amplifierNPR

P P

I t Outputf f


Input Output

DCDC

• Input power PDC in WattsInput power PDC in Watts• Output power PRF in Watts

O t t ffi i P P• Output efficiency = PRF / PDC

– Usually expressed in percent• Power added efficiency

– Removes the contribution of input RFp– PAE = (PRF - PRFin ) / PDC


See example data sheetSee example data sheet


KaBand amp.pdf

mmic design and development - sharifee.sharif.edu/~mmic/notes/measurements.pdf · microwave...

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