RF Electronics Chapter 5: Frequency Mixers Page 133
2022, C. J. Kikkert, James Cook University, ISBN 978-0-6486803-9-0.
Figure 5.35. IF spectrum of a double balanced diode mixer as a down-converter.
Figure 5.36. IF voltage for a balanced diode mixer as a down-converter.
Figure 5.36 shows the IF voltage. There is a significant high frequency content.
Figure 5.37 shows the same IF voltage with the IF signal passed through a 25 MHz low
pass filter to remove the high frequency components. The waveform looks like an ideal
Sine wave and there is little change in the output as the LO power is changed between
0 dBm and 10 dBm. The LO AM noise will thus have little effect on the IF output.
Applying the low pass filter at the IF output reduces the conversion loss by 0.47 dB, due
to a short circuit being presented at >25 MHz at the IF port of the mixer.
RF Electronics: Design and Simulation
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