ECE 453 Fall 2007
ECE 453 Name: ____________________
Lab #4 Summary Score: _______ / 70
All check points are worth 2 points except where otherwise noted.
Mixer Characterization
Briefly describe the theory behind the mixer’s operation. Draw measurement setup.
Explain why more than two peaks are outputted by the mixer.
Measure the powers of the RF and LO inputs to the mixer
(6 pts) Identify ~15-20 spectral components, including all major peaks from 0-70 MHz. Record the
frequency, magnitude, and origin of all peaks.
Estimate the RF to IF isolation, LO to IF isolation, and conversion loss for the sum and difference terms.
Ceramic Filter Characterization
Describe test setup.
Measure filter’s S-parameters and plot the S21’s for all simulated terminations in ADS (include markers).
Choose optimal termination resistance and explain the choice in terms of filter characteristics.
(4 pts) Design impedance matching network for input and output transformations to 50 Ohms. Verify
matching networks in ADS and include plots. Explain the choice of topology.
(4 pts) Add impedance transformers to the filter circuit. Plot S21, and determine the magnitude in the
passband. Also, find the 3dB and 20 dB bandwidths.
Receiver Performance
Construct superheterodyne with signal generator input. What is the first IF? Determine choice(s) for LO1.
(4 pts) For tone-modulated input, show frequency spectrum at each point in the circuit. Explain what
changing the frequency deviation does to the output waveform.
Connect the input to the antenna and tune signal generator to receive a local FM station. Comment on
sound quality.
Replace LO1 signal generator with Lab 2 VCO. Comment on sound quality.
Image Response
Describe the setup to measure the spurious signals – new from TA.
(6 pts) Calculate the frequencies of 3 spurious responses and define their origin. Include observations.
Where would the spurious frequencies for the low LO.
Explain how knowing the spurious frequencies can affect receiver implementation. (< 1 paragraph)
General Lab Procedure
(14 pts) Introductions, conclusions, troubleshooting, and discussion included.
(6 pts) Lab attendance, notebooks used during lab.
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