ABSTRACT
Three operational amplifiers with class-AB output stages were designed during HIGHTECS: one with a PMOS input stage, one with a NMOS input stage and one with a rail-to-rail input stage. The opamps have been used in the signal conditioning blocks as well as the bias block for stable generation of currents and voltages, and these, in turn, have been used to bias the strain, temperature, and frequency channels for signal conditioning. While the opamps were not measured directly, their performances were indirectly evaluated in the signal conditioning instrumentation amplifiers and in the voltage to voltage and voltage to current converters in the bias block. The OpAmp model for simulation includes layout capacitive and resistive parasitics. Functionally, the reference voltage generator and bias circuits provide the needed voltages and currents for the opamp-based signal conditioning circuits for each type of sensor.
