sampler circuit for microwave in-room...

Presented bySu Kian Thian

2263356Supervised by

Prof. Dr.-Ing. K. SolbachFachgebiet

Hochfrequenztechnikan der

Universität Duisburg-Essen

Sampler Circuit for Microwave In-Room Communications

Max Mustermann, 01.02.2005

Outline

• Motivation

• Sampling

• Circuit Analysis

• Design Analysis

• Measurement Result


Motivation

• To design a sampler circuit

− RF signals with frequency range of 1GHz to 4GHz− Harmonic sampling with low sampling frequency− SMD components


Sampling

• What is sampling?− Process of taking sample of an analog signal periodically


Circuit Analysis


• Two-diode Sampling Gate− Switches− Balanced configuration

• Operational Amplifier− Isolation− Finite gain

DC voltage applied to back bias the diode

50ohm matching impedance

Feedback resistor


Design Analysis

• Transmission Line


• SMD Components− DC Blocking Capacitor

Resonant frequency – S-parameters0603100pF and 3.3pF

− Microwave AmplifierGALI-6+Frequency range of DC to 4GHzGain of 10dB to 12.3dB

− BalunTC1-1-43+Ratio 1:1Operating frequency range of 650 to 4000MHz


− Schottky DiodeSchottky diode BAT62-03WFast switching and low forward voltage drop

− Matching Impedance100OhmResonant frequency0603

− High Pass FilterRC filterBlock unused DC product1kOhm and 10nF

− Trimmer10kOhm

− Operational AmplifierUA741Feedback resistance = 1.5kOhm


Measurement Result

• Setup

Pulse signal(LO)

RF signal

Output signal(IF)


Case RF frequency

F

, RF input power

Pin

, IF frequency

FIF

, Sampling frequency,

Fs

1 Fixed, 1GHz Fixed, -10dBm Varied Varied

2 Varied Fixed, -10dBm Varied Fixed, 250MHz

3 Fixed, 1GHz Varied Varied Fixed, 250MHz


-6

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Volta

ge G

ain,

dB

Frequency of IF Signal, kHz

F = 1GHz

F = 1.5GHz

F = 2GHz

F = 2.5GHz

Bandwidth = 400kHz


-25

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Con

vers

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Gai

n, d

B


Fs = 100MHzFs = 125MHzFs = 200MHzFs = 250MHzFs = 500MHz


-35

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Con

vers

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Gai

n, d

B


F = 1GHzF = 1.5GHzF = 2GHzF = 2.5GHz

Error at 2GHz!!!


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n, d

B


Pin = 0dBmPin = -5dBmPin = -10dBmPin = -15dBmPin = -20dBmPin = -25dBm

-10dBm is thesaturated inputpower to have linear characteristic


• 1dB Compression Indicates the upper limit of the power level of the RF input signal.


• Isolation− RF-LO isolation = 30dB

decreased with increasing sampling frequency− IF-LO isolation = 25dB

System imbalance

Amount of power leakage that leaks from one port to another


Frequency domainof pulse signals----uniform!


Sin Nin Noise figure, F

10dB -57dBm -124dBm 57dB

20dB -77dBm -124dBm 56dB


• New Circuit

LEE-39+

TL071


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Con

vers

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Gai

n, d

B


F=1GHz

F=1.5GHz

F=2GHz

F=2.5GHz

No error at 2GHz!!


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Volta

ge G

ain,

dB


F = 1GHzF = 1.5GHzF = 2GHzF = 2.5GHz

Bandwidth = 900kHz

sampler circuit for microwave in-room...

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