Class AB Micropower Operational Amplifiers
Class AB amplifiers contribute to minimize power in several ways: on the one hand by decoupling the large signal (i.e. slew rate and current through the load resistor), and small signal (i.e. stability) requirements on the output stage; on the other hand by reducing quiescent current consumption when the signal to be processed, as in this case the cardiac signal, is “active” during only a small part of the system cycle. When a class A amplifier is applied, as was the case of the pacemaker sense channel described in Chapter 2, the class A bias current, which is consumed permanently, must be dimensioned according to the output current demand when a large signal is applied. However, this large signal is only present during a very small part of the system cycle.
KeywordsParasitic Capacitance Output Stage Phase Margin Loop Gain Current Mirror
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