Wcm. Renirie et al., PARALLEL FEEDFORWARD CLASS-AB CONTROL-CIRCUITS FOR LOW-VOLTAGE BIPOLAR RAIL-TO-RAIL OUTPUT STAGES OF OPERATIONAL-AMPLIFIERS, Analog integrated circuits and signal processing, 8(1), 1995, pp. 37-48
A new family of class-AB control circuits for bipolar rail-to-rail out
put stages of operational amplifiers is presented. Step by step, we re
port the development of five simple class-AB control circuits showing
the advantages of using parallel feedforward. The circuits have been d
esigned in such a way that temperature, supply voltage and process par
ameters have little influence. To test the output stages, one of them
has been implemented in a very simple two-stage operational amplifier
on a semi-custom chip. Measurements show a bandwidth of 2.5 MHz, a gai
n of 40 dB, a quiescent current of 23 mu A and a maximum output curren
t of 250 mu A. Simulation results of three other simple operational am
plifiers with the new class-AB control circuits are shown, which have
a higher gain and maximum output current.