RF Electronics Chapter 5: Frequency Mixers Page 127
2022, C. J. Kikkert, James Cook University, ISBN 978-0-6486803-9-0.
5 MHz signal. The LO signal appearing in the IF spectrum is extremely small (-304.8 dB
in the figure 5.27 data). Bert Henderson shows that these harmonic levels depend on the
diodes class [3], which determines the mixer LO level required. The isolation depends on
how well the diodes are matched. In the computer simulation, the diodes are identical. In
hardware, this is not the case.
Figure 5.27. IF spectrum of a balanced diode mixer as a down-converter.
Table 5.1 Frequency components of figure 5.27
Frequency
MHz
Down Convert
Due to
Up Convert Due to
5 LO-RF IF
15 3*(LO-RF) 3IF
25 5*(LO-RF) 5IF
80 LO-5IF
90 2RF-LO LO-3IF
100 RF LO-IF
110 2LO-RF LO+IF
120 4LO-3RF LO+3IF
130 LO+5IF
185 2LO-5IF
195 3RF-LO 2LO-3IF
205 RF+LO 2LO-IF
215 3LO-RF 2LO+IF
225 5LO-3RF 2LO+3IF
235 2LO+5IF
RF Electronics: Design and Simulation
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