Chopper-stabilized operational amplifier including low-noise chopper switch

摘要

To minimize noise generation a chopper switch for a chopper stabilized operational amplifier includes a balanced bridge circuit with two pairs of high-side and low-side transistors connected in parallel. The transistors are not turned completely off but operate in the manner of variable resistors between a high-resistance level and a low- resistance level. One or more additional transistors are include to provide a parasitic capacitance in the break-before-make interval when all of the other transistors are turned off. To provide rail-to-rail operation, complementary circuits contain N-channel and P-channel transistors are connected in parallel between the input and output terminals of the chopper switch.