US 10,312,865 B2 · Voltage range extension for difference amplifier

Abstract

A difference amplifier circuit can be used to amplify a differential input signal representative of a current flowing through a current sensing element, such as a resistor. In certain applications, a common mode voltage established at an input of the difference amplifier circuit can be greater in magnitude than a supply voltage provided to the difference amplifier circuit. A component of the differential input signal, such as one polarity of the differential signal, can be used to power the difference amplifier circuit. Such powering of the difference amplifier by the component of the differential input signal can be performed selectively, such as when a magnitude of the common mode voltage exceeds the supply voltage or another specified threshold. In this manner, a common mode input voltage capability can be greater in magnitude than a magnitude of a supply input voltage provided to an integrated circuit including the difference amplifier circuit.

Claims20

Dependent claims

An electrical apparatus for generating a signal indicative of a monitored voltage difference, the apparatus comprising:

an integrated circuit comprising:
a difference amplifier circuit comprising:
a two-terminal input to receive a differential signal, and
an output to provide the signal indicative of the input differential signal;
and
an amplifier control circuit, electrically coupled to the difference amplifier circuit, to compare a signal representative of a common-mode input voltage at the input of the difference amplifier circuit to a specified threshold, and, in response, when the signal representative of the common-mode input voltage exceeds the specified threshold, to electrically couple a first terminal of the two-terminal input to the difference amplifier circuit to power the difference amplifier circuit;
wherein the amplifier control circuit comprises a current source;
and
wherein the current source is capable of being electrically coupled to a second terminal of the two-terminal input to compensate for an offset between respective input currents through the first and second terminals, wherein the second terminal comprises a polarity opposite the first terminal.

6 more elements

An electrical apparatus for generating a signal indicative of a monitored current, the apparatus comprising:

a current sensing element located in series with an electrical load;
an integrated circuit comprising:
a difference amplifier circuit comprising:
an input compatible with a common-mode input voltage exceeding a supply input voltage of the integrated circuit;
and
an output to provide the signal indicative of the monitored current;
and
an amplifier control circuit, electrically coupled to the difference amplifier circuit, including a comparator to compare a signal representative of a common-mode input voltage at the input of the difference amplifier circuit to a specified threshold, and, in response, when the signal representative of the common-mode input voltage exceeds the specified threshold, to power the difference amplifier circuit using an input terminal of the difference amplifier circuit, the difference amplifier circuit separate from the comparator included as a portion of the amplifier control circuit;
wherein the amplifier control circuit is configured to compensate for an offset between respective input currents through respective first and second input terminals of the difference amplifier circuit when the difference amplifier circuit is powered using an input terminal amongst the respective first and second input terminals.

6 more elements

Dependencies are inferred from the claim text.

Voltage range extension for difference amplifier

Life of this patent

Voltage range extension for difference amplifier

Life of this patent

Abstract

Claims20