Patent ID: 6542034
Filing Date: 2003-04-01
Classification: H03F

Abstract:
An operational amplifier for driving a load and comprising:a first stage; and a second stage including an input connected to an output of said first stage and an output connected to the load, said second stage comprising between the input and output thereof a first signal path for driving the load in a first direction, a first load transistor in the first signal path and being driven by the output of said first stage, a second signal path for driving the load in an opposite direction, a second load transistor connected to said first load transistor and in the second signal path for driving the load in the second direction, said first and second signal paths have substantially equal gains for low level signals, substantially equal output impedances for low and high level signals, and substantially equal output-current capabilities, and a signal-level translation circuit connected to the output of said first stage for driving said second load transistor, said signal-level translation circuit comprising first and second circuit branches connected as a current mirror, said first circuit branch comprising a first translation transistor comprising a control terminal connected to the output of said first stage and being driven by the output, and a second translation transistor connected in series with said first translation transistor and being configured as a diode, and said second circuit branch comprising a third translation transistor comprising a control terminal connected to a control terminal of said second translation transistor, and a fourth translation transistor connected in series with said third translation transistor, a common node between said third and fourth translation transistors defining a low-impedance output node.