Digital Signal Processing Reference
In-Depth Information
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Fig. 23
Implementation of a second-order SC sigma-delta modulator
5.6
Differential SC Circuits
In many SC circuit applications, fully differential circuits are preferred over the
single-ended counterparts. In a differential circuit the signal is carried by two wires
and their voltage difference represents the signal value. Differential circuits are
tolerant against power supply noise, clock feedthrough, switch charge injection
errors and common-mode noise in general, because noise coupled to both wires
does not affect the difference. A differential circuit also has a larger dynamic range
of the signal. A drawback is larger circuit size, since the circuitry is doubled, except
the amplifiers. As an example, Fig.
23
shows a second-order sigma-delta modulator
implemented as a differential SC circuit. In this circuit the amplifiers are differential
