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2. Or more commonlly, mixers are symbolized as multipliers that generate an
output signal that is the product of two (or more) input signals.
Thus the objective for this chapter is to cover analog mixer circuits. Switch-mode
mixers will be explained in Chapter 15.
Adding Circuits Versus Mixing Circuits
Analog circuits that are adders will sum or combine two signals without distortion
signals at the output. The output is just the summation of the two input signals.
Figure 14-1 shows various examples of summing circuits. The top circuit is a simple
two-resistor signal-combining network. And tihe bottom circuit shows an operational
amplifier ( op amp) summing circuit that has an output of
