Page 317 - Complete Wireless Design
P. 317
Mixer Design
316 Chapter Seven
Figure 7.2 (a) A single-diode mixer and a (b) double-diode mixer stage.
Figure 7.3 A basic single-diode
mixer circuit with filtering.
Single-balanced mixers, as shown in Fig. 7.4, are composed of two balanced
diodes, a balun (which converts the unbalanced LO output to a balanced mix-
er input, matches the diodes to the port’s impedance, helps in port-to-port iso-
lation, and balances the diodes), and two filters (one each at the RF and IF
ports for improved isolation). These mixer types will balance out (cancel) and
filter the LO power, preventing excessive LO feedthrough at the RF and IF
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