ABSTRACT
This chapter focuses on precision switching applications. Errors due to ON resistance, drift, leakage, charge injection, layout, and interconnections are examined. Techniques for compensation and minimizing these errors are presented in the context of some fairly common precision switching applications. The preferred approach is to design the circuit such that ON resistance is not critical to the operation of the circuit. Circuits that place the switch in series with a high impedance point or circuits that place no significant voltage across the switch channel reduce the circuit’s dependence on the ON resistance value. Analog switches exhibit leakage from both source and drain terminals, and when the switch is both ON and OFF. Charge injection is the cause of most switching glitches seen in analog switch circuits. A practical rule of thumb when designing switches into data conversion systems is to allow only 10% of the total error budget to the switch.
