OPERATIONAL AMPLIFIER CIRCUIT

摘要

In a folded cascode operational amplifier circuit, a source is connected to a back gate in each of third and fourth transistors that are cascode-connected to first and second transistors, which are an electric current source that returns an electric current signal output by a differential pair of an input stage. In the third and fourth transistors, an active parasitic element exists due to its device structure. When a falling edge signal of a rectangular wave is input, and electric current is supplied to the source of the third transistor to increase its electric potential, electric current flows into the drain from the back gate via the active parasitic element in an on state, in order to rapidly charge a capacitor. Thereby, a fifth transistor turns on within a shorter time, in order to improve an internal slew rate.

主权项

1. A folded cascode operational amplifier circuit comprising:
a first electric current source including a P-channel transistor; a differential pair including P-channel transistors, wherein electric current is supplied from the first electric current source to the differential pair, and a differential voltage is input into the differential pair; a second electric current source including a pair of N-channel transistors that return electric current output from the differential pair; a cascode circuit including a pair of N-channel transistors that are cascode-connected to the second electric current source; a third electric current source including a pair of P-channel transistors, for supplying electric current to the cascode circuit; an N-channel output transistor configured to amplify a voltage output from a node of connection between the cascode circuit and the third electric current source; and a phase compensation capacitor connected to the node, wherein each of the transistors of the cascode circuit includes a source and a back gate connected to each other.