Analog MOS Integrated Circuits for Signal Processing

Chapter Seven

NONIDEAL EFFECTS IN SWITCH ED-CAPACITOR CIRCUITS

As discussed earlier, switched-capacitor circuits are usually intricate systems containing many components and multiple feedback loops, and are realized normally in a fully integrated form. As a result of the integrated realization, many unavoidable parasitic effects occur in the circuit. If these nonideal effects are not considered carefully, and are not minimized or eliminated by appropriate design techniques, then they can make the fabricated circuit inoperable, or at least deficient in performance. One such parasitic effect, involving stray capacitances, has already been discussed in Section 5.3, where we have also described an efficient method for avoiding its detrimental effects on the response of switched-capacitor integrators.

In this chapter, additional nonideal effects will be considered. We shall describe the origin of each effect, analyze its influence on the performance of the circuit, and (whenever available) discuss methods for their elimination.

Because of their great impact, the effects described in the following should not be considered minor practicalities or mundane second-order phenomena. Any design effort in which these potential problems are not considered is likely to turn into a futile exercise which yields an inoperative product. Hence, the importance of the topics in this chapter is comparable ...