Patent ID: 8390379
Filing Date: 2013-03-05
Classification: H03F

Abstract:
1. An amplifier input stage and slew boost circuit comprising: a differential input pair of transistors connected to a pair of amplifier inputs; a constant current source; a pair of maximum voltage detecting transistors with control inputs connected to buffer transistor outputs, the pair of maximum voltage detecting transistors having a common input connected to the voltage source through an input of a first current mirror, the pair of maximum voltage detecting transistors having a common output connected to a second constant current source at a maximum input voltage node; a pair of minimum voltage detecting transistors with control inputs connected to the buffer transistor outputs, the pair of minimum voltage detecting transistors having a common input connected to the constant current source at a minimum input voltage node, the pair of minimum voltage detecting transistors having a common output connected to the differential input pair of transistors through a second current mirror; a diode-connected transistor connected between an output of the first current mirror and the second constant current source at a maximum input voltage node; and a transistor having a control input connected to a control input of the diode-connected transistor, an input connected to the constant current source at the minimum input voltage node, and an output connected to a ground, wherein a conductance of the transistor is inversely proportional to a difference between a voltage at the maximum input voltage node and a voltage at the minimum input voltage node.