US 10,320,337 B2 · Fully-differential operational amplifier system

Abstract

A dynamic common reference input (CMRI) signal may be provided to an operational amplifier, or “op-amp,” in an amplifier system to reduce the common mode ripple of the fully-differential op-amp, while adding little or no noise in the amplifier system. The dynamic CMRI signal may be controlled such that a common-mode component of two amplifier input nodes of the operational amplifier is made approximately independent of two input signals received at two system input nodes of the amplifier system. An amplifier system with the dynamic CMRI may be used in class-D amplifiers, such as amplifiers for audio systems that generate output for headphones or speakers.

Claims29

Dependent claims

A fully-differential amplifier system having two system input nodes and two system output nodes, comprising:

a first operational amplifier with a common-mode reference input (CMRI), wherein the first operational amplifier comprises two amplifier input nodes coupled to the two system input nodes and two amplifier output nodes coupled to the two system output nodes, and wherein the first operational amplifier is configured to adjust a common mode component of the output signal to approximately equal a CMRI voltage received at the CMRI;
and
a dynamic CMRI generation block configured to dynamically generate the CMRI voltage for the first operational amplifier, wherein the dynamic CMRI generation block is configured to generate the CMRI voltage such that a common-mode component of the two amplifier input nodes is made approximately independent of two input signals received at the two system input nodes.

An apparatus, comprising:

a fully-differential amplifier system having two system input nodes and two system output nodes comprising:
a first operational amplifier with a common-mode reference input (CMRI), wherein the first operational amplifier comprises two amplifier input nodes coupled to the two system input nodes and two amplifier output nodes coupled to the two system output nodes, and wherein the first operational amplifier is configured to adjust a common mode component of the output signal to approximately equal a CMRI voltage received at the CMRI;
two input impedances respectively coupled between the two system input nodes and the two amplifier input nodes;
and
two feedback impedances respectively coupled between the two system output nodes and the two amplifier input nodes;
and
a controller comprising:
a signal-dependent common-mode generator (SDCG) coupled between the two system input nodes and the CMRI, wherein the SDCG is configured to generate the CMRI voltage such that a common-mode component of the two amplifier input nodes is made approximately independent of two input signals received at the two system input nodes.

5 more elements

Dependencies are inferred from the claim text.

Fully-differential operational amplifier system

Life of this patent

Fully-differential operational amplifier system

Life of this patent

Abstract

Claims29