Slew rate and settling time improvement circuitry and method for 3-stage amplifier

摘要

An operational amplifier (1B) amplifies an input signal (Vin) to produce an output signal (Vout), and includes a 3-stage amplifier (1C) including a first amplifier stage (2) receiving the input signal, a second amplifier stage (3) driven by the first amplifier stage (2), and a third amplifier stage (4) driven by the second amplifier stage to produce the output signal. A slew detection current (Idetect) is generated when the input signal (Vin) exceeds a certain magnitude, and is converted to a control signal (41) that operates a switch (MN0) to short-circuit output conductors of the first amplifier stage to prevent signal charge from building up on capacitances associated with the output of the first amplifier stage during slewing. The three stage amplifier can be a chopper-stabilized, notch-filtered amplifier.