Two-stage rail-to-rail operational amplifier
First Claim
1. An operational amplifier, comprising:
- a differential input circuit adapted to receive a differential input signal to produce an amplified differential output signal for application to first and second nodes;
said differential input circuit having a common-mode control circuit that produces first and second common-mode control voltages on said first and second nodes, whereby said common-mode control voltages are combined with said amplified differential output signal on said first and second nodes to produce a first stage differential output signal;
and a high-swing output stage connected to receive the first stage differential output signal.
1 Assignment
0 Petitions
Accused Products
Abstract
A two-stage class-AB operational amplifier, that can be implemented either with bipolar or MOS transistors, includes a differential input circuit adapted to receive a differential input signal to produce an amplified differential output signal for application to first and second nodes. The differential input stage has a common-mode control circuit that produces first and second common-mode control voltages on the first and second nodes. The common-mode control voltages are combined with the amplified differential output signal on the first and second nodes to produce a first stage differential output signal. A high-swing output stage is connected to receive the first stage differential output signal. First and second current mirrors each have a mirror transistor to mirror an output current produced in response to the differential input signals on respective lines including the first and second nodes. The common-mode control circuit is in series with mirror transistors of the first and second current mirrors. A circuit clamps the first and second nodes at a voltage of 2VBE below the supply voltage, and clamps the voltage at the second node at a voltage of 2VBE above the reference potential, enabling the circuit to operate with improved power-supply rejection ratios.
-
Citations
28 Claims
-
1. An operational amplifier, comprising:
-
a differential input circuit adapted to receive a differential input signal to produce an amplified differential output signal for application to first and second nodes; said differential input circuit having a common-mode control circuit that produces first and second common-mode control voltages on said first and second nodes, whereby said common-mode control voltages are combined with said amplified differential output signal on said first and second nodes to produce a first stage differential output signal; and a high-swing output stage connected to receive the first stage differential output signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
-
-
10. An operational amplifier, comprising:
-
a differential input circuit adapted to receive a differential input signal to produce an amplified differential output signal on first and second nodes; said differential input circuit having a common-mode control circuit that produces first and second common-mode control voltages on said first and second nodes, whereby said common-mode control voltages are combined with said amplified differential output signal on said first and second nodes to produce a first stage differential output signal; a circuit for clamping the first and second nodes at a predetermined level with respect to the supply voltage and reference potential; and a high-swing output stage connected to receive the first stage differential output signal. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19)
-
-
20. A two-stage class-AB operational amplifier, comprising:
-
a differential input circuit adapted to receive a differential input signal to produce an amplified differential output signal on first and second nodes; said differential input circuit having a common-mode control circuit that produces first and second common-mode control voltages on said first and second nodes, whereby said common-mode control voltages are combined with said amplified differential output signal on said first and second nodes to produce a first stage differential output signal; and a high-swing output stage connected to receive the first stage differential output signal, said high-swing output stage including a buffer stage connected to receive said first stage differential output signal and a pair of output transistors connected to produce an operational amplifier output, and a class-AB mode biasing circuit for biasing said pair of output transistors. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28)
-
Specification