Sampler Circuit for Microwave In-Room...
Transcript of 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 Page 2
Outline
• Motivation
• Sampling
• Circuit Analysis
• Design Analysis
• Measurement Result
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Motivation
• To design a sampler circuit
− RF signals with frequency range of 1GHz to 4GHz− Harmonic sampling with low sampling frequency− SMD components
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Sampling
• What is sampling?− Process of taking sample of an analog signal periodically
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• 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
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• 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
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− 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
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Measurement Result
• Setup
Pulse signal(LO)
RF signal
Output signal(IF)
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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
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Frequency of IF Signal, kHz
F = 1GHz
F = 1.5GHz
F = 2GHz
F = 2.5GHz
Bandwidth = 400kHz
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Frequency of IF Signal, kHz
Fs = 100MHzFs = 125MHzFs = 200MHzFs = 250MHzFs = 500MHz
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Frequency of IF Signal, kHz
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Error at 2GHz!!!
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Frequency of IF Signal, kHz
Pin = 0dBmPin = -5dBmPin = -10dBmPin = -15dBmPin = -20dBmPin = -25dBm
-10dBm is thesaturated inputpower to have linear characteristic
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• 1dB Compression Indicates the upper limit of the power level of the RF input signal.
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• 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
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Sin Nin Noise figure, F
10dB -57dBm -124dBm 57dB
20dB -77dBm -124dBm 56dB
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Frequency of IF Signal, kHz
F=1GHz
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No error at 2GHz!!
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Frequency of IF Signal, kHz
F = 1GHzF = 1.5GHzF = 2GHzF = 2.5GHz
Bandwidth = 900kHz