Low voltage rail-to-rail CMOS input stage
AssigneeStandard Microsystems Corporation
InventorTroy L. Stockstad
Life of this patent
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Abstract
The present invention discloses a low voltage rail-to-rail CMOS input stage. The input stage includes a differential pail of P-channel metal oxide semiconductor field effect (PMOS) transistors, which produces differential output current signal. The input stage further includes a pair of N-channel depletion-mode metal oxide semiconductor field effect (NMOS) transistors, coupled to the bulk terminals of the differential pair of PMOS transistors, for receiving an input signal. The depletion-mode NMOS transistors further act as source follower devices to drive the bulk terminals of the differential pair of PMOS transistors.
Claims39
A low voltage operational amplifier input stage, the input stage comprising:
- a differential pair of P-channel metal oxide semiconductor field effect (PMOS) transistors, each PMOS transistor having a bulk terminal, wherein the PMOS transistors produce a first and a second current signal;
- and
- a pair of N-channel depletion-mode metal oxide semiconductor field effect (NMOS) transistors coupled to the bulk terminals of the differential pair of PMOS transistors for receiving an input signal and for acting as source follower devices to drive the bulk terminals of the differential pair of PMOS transistors.
A method for providing an output signal from an input stage of a low voltage operation amplifier, the method comprising the operations of:
- providing an input signal to a pair of N-channel depletion-mode metal oxide semiconductor field effect (NMOS) transistors coupled to bulk terminals of a differential pair of P-channel metal oxide semiconductor field effect (PMOS) transistors;
- and
- providing a differential output current signal using the differential pair of PMOS transistors.
An application specific integrated circuit (ASIC) having an input stage for a low voltage operational amplifier input stage, the ASIC comprising:
- a differential pair of P-channel metal oxide semiconductor field effect (PMOS) transistors, each PMOS transistor having a bulk terminal, wherein the PMOS transistors produce a differential current signal;
- and
- a pair of N-channel depletion-mode metal oxide semiconductor field effect (NMOS) transistors coupled to the bulk terminals of the differential pair of PMOS transistors for receiving an input signal and for acting as source follower devices to drive the bulk terminals of the differential pair of PMOS transistors.
An operational amplifier input stage, the input stage comprising:
- a voltage input network, wherein the voltage input network receives a differential input signal, and wherein the voltage input network provides a voltage input network output signal, the voltage input network output signal being above VEE when the differential input signal is at VEE;
- and
- an transconductance network, wherein the transconductance network receives the voltage input network output signal, and wherein the transconductance network provides a differential output signal.
An operational amplifier capable of operating on low supply voltages, the operational amplifier comprising:
- an input stage having a differential pair of PMOS transistors, and a pair of NMOS transistors;
- and
- an output stage.
A low voltage operational amplifier input stage, the input stage comprising:
- a differential pair of N-channel metal oxide semiconductor field effect (NMOS) transistors, each NMOS transistor having a bulk terminal, wherein the NMOS transistors produce a first and a second current signal;
- and
- a pair of P-channel depletion-mode metal oxide semiconductor field effect (PMOS) transistors coupled to the bulk terminals of the differential pair of NMOS transistors for receiving an input signal and for acting as source follower devices to drive the bulk terminals of the differential pair of NMOS transistors.
A low voltage operational amplifier input stage, the input stage comprising:
- a differential pair of N-channel metal oxide semiconductor field effect (NMOS) transistors, each NMOS transistor having a bulk terminal, wherein the NMOS transistors produce a first and a second current signal;
- and
- a pair of JFET transistors coupled to the bulk terminals of the differential pair of NMOS transistors for receiving an input signal and for acting as source follower devices to drive the bulk terminals of the differential pair of NMOS transistors.
Dependencies are inferred from the claim text.