Apparatus for sensing differential voltages with high common-mode levels
AssigneeNational Semiconductor Corporation
InventorWillem Johannes Kindt
Life of this patent
Estimating the term…
Abstract
A differential voltage amplifier includes a dynamic level shifter circuit and an amplifier circuit. The dynamic level shifter circuit includes high-impedance current sources and resistors that are arranged to move the common-mode levels of a differential input signal to a signal level that is suitable for the amplifier circuit. The amplifier circuit may be single-ended or differential. The dynamic level shifter circuit may include one or more current sources that are arranged to provide improved performance for low common-mode levels. A dynamic biasing scheme may be employed to improve operation over varied common-mode ranges. A trimming circuit may be used to adjust offsets in the system. A DC chop arrangement may be employed to remove offsets in the system.
Claims20
An apparatus that is arranged to provide an amplified signal in response to a differential input signal that is provided across first and second input terminals, comprising:
- a first resistor that is coupled between the first input terminal and a first node;
- a second resistor that is coupled between the second input terminal and a second node;
- a first current source that is coupled between the first node and a power supply, wherein the first current source is configured to respond to a drive signal;
- a second current source that is coupled between the second node and a power supply, wherein the second current source is configured to respond to the drive signal;
- a first amplifier circuit that is arranged to provide the drive signal in response to a common-mode sense signal, wherein the common-mode sense signal is associated with a common-mode portion of the differential input signal;
- and
- a second amplifier circuit that is coupled to at least one of the first and second node, wherein the second amplifier circuit is arranged to provide the amplified output signal.
An apparatus that is arranged to provide a differential amplified signal in response to a differential input signal that is provided across first and second input terminals, comprising:
- a first resistor that is coupled between the first input terminal and a first node;
- a second resistor that is coupled between the second input terminal and a second node;
- a first current source that is coupled between a third node and a power supply, wherein the first current source is configured to respond to a drive signal;
- a second current source that is coupled between a fourth node and a power supply, wherein the second current source is configured to respond to the drive signal;
- a first amplifier circuit that is arranged to provide the drive signal in response to a common-mode sense signal, wherein the common-mode sense signal is associated with a common-mode portion of the differential input signal;
- a switching circuit that is arranged to selectively couple the first node to the third node in a first operating phase, selectively couple the first node to the fourth node in a second operating phase, selectively couple the second node to the fourth node in the first operating phase, and selectively couple the second node to the third node in the second operating phase;
- and
- a second amplifier circuit that is coupled to the first and second nodes, and arranged to provide the differential amplified signal.
An apparatus that is arranged to provide an amplified signal in response to an input signal that is provided across first and second input terminals, comprising:
- a first resistive means that is arranged to couple a first level shifted signal to a first node;
- a second restive means that is arranged to couple a second level shifted signal to a second node;
- a first current source means that is arranged to cooperate with the first resistive means, wherein the first current source means is responsive to a drive signal;
- a second current source means that is arranged to cooperate with the second resistive means, wherein the second current source means is responsive to a drive signal;
- a drive means that is arranged to provide the drive signal in response to at least one of a reference signal and a common-mode sense signal;
- and
- an amplification means that is arranged to amplify signals associated with at least one of the first and second nodes to provide the amplified signal.
Dependencies are inferred from the claim text.