Realizations of Operational Amplifiers

In the previous chapters, the theory necessary for designing low-offset CMOS operational amplifiers has been discussed. This chapter focuses on the design of two complete general-purpose low-offset wide-bandwidth operational amplifiers, which have been designed using this theory. Chapter 6 will focus on the realization of instrumentation amplifiers.

In section 5.2 a chopper offset-stabilized operational amplifier will be described. In this implementation, a sample-and-hold is used to reduce chopper ripple, as discussed in section 3.3.4. In section 5.3, a chopper and auto-zero offset-stabilized operational amplifier will be described. Both amplifiers are designed to be unity-gain stable with a 100 pF load capacitor and achieve a unity-gain frequency of 1MHz with a 60-degree phase margin.