Performance of Operational Amplifiers With Electronic Mode Switching

The linear-circuit performance equation for an important class of mode-switched operational amplifiers is derived to identify errors caused by finite feedback loop gains, switch resistance, and follower-amplifier source impedance. Errors due to capacitor dielectric absorption, switching spikes, dc leakage, and current limiting are discussed with reference to an electronically switched integrator (sample-hold or analog-memory circuit), and various design requirements are listed.