Input common mode voltage compensation circuit
AssigneeAnalog Devices, Inc.
InventorsRobert Libert, Khiem Quang Nguyen
Life of this patent
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Abstract
A voltage level shifter for a direct coupling of an external voltage source to a common mode of a circuit may include an amplifier, a voltage-controlled current source, a first and second resistors. A first input of the amplifier may be connected to the common mode. A second input of the amplifier may, via the first and second resistors, receive a voltage indicative of the external voltage source. The output of the amplifier may indicate a voltage difference between the first and second inputs. The voltage-controlled current source may be controlled by the voltage difference to supply a current to a common node of the first and second resistors so that the voltage difference between the first and second inputs may be minimized.
Claims18
A voltage level shifter for a direct coupling of a voltage source to an amplifier including a common mode at a common-mode level, comprising:
- an amplifier including a first input, a second input, and an output, the first input being coupled to the common mode and the output indicating a voltage difference between the first and second inputs;
- a voltage-controlled current source having a control input coupled to the output of the amplifier and an output for supplying an output current as a function of a voltage at the control input;
- a first resistor being coupled between the external voltage source and the output of the voltage-controlled current source;
- and
- a second resistor being coupled between the output of the voltage-controlled current source and the second input of the amplifier,
- wherein the output current from the voltage-controlled current source supplies to the second resistor so as to minimize the voltage difference between the first and second inputs of the amplifier.
A voltage level shifter for a direct coupling of a voltage source to an amplifier including a common mode at a common-mode level, comprising:
- an amplifier including a first input, a second input, and an output, the first input being coupled to the common mode and the output indicating a voltage difference between the first and second inputs;
- back-to-back connected first and second voltage-controlled current sources each having a control input coupled to the output of the amplifier and an output for supplying an output current as a function of a voltage at the control input;
- a first resistor being coupled between the external voltage source and the output of the first voltage-controlled current source;
- a second resistor being coupled between the output of the first voltage-controlled current source and the second input of the amplifier;
- a third resistor being coupled between the external voltage source and the output of the second voltage-controlled current source;
- and
- a fourth resistor being coupled between the output of the second voltage-controlled current source and the second input of the amplifier,
- wherein the output currents from the first and second voltage-controlled current sources supply to the second and fourth resistors, respectively, so as to minimize the voltage difference between the first and second inputs of the amplifier.
An analog-to-digital converter (ADC), comprising:
- a voltage level shifter for directly coupling an external voltage source to an amplifier including a common mode at a common-mode level, wherein the voltage level shifter includes:
- an amplifier including a first input, a second input, and an output, the first input being coupled to the common mode and the output indicating a voltage difference between the first and second inputs;
- a voltage-controlled current source having a control input coupled to the output of the amplifier and an output for supplying an output current as a function of a voltage at the control input;
- a first resistor being coupled between the external voltage source and the output of the voltage-controlled current source;
- and
- a second resistor being coupled between the output of the voltage-controlled current source and the second input of the amplifier,
- wherein the output current from the voltage-controlled current source supplies to the second resistor so as to minimize the voltage difference between the first and second inputs of the amplifier.
A circuit for directly coupling an external voltage bias to a common mode of a circuit, comprising:
- a voltage amplifier circuit including a first input for receiving a first input voltage, a second input for receiving a second input voltage, and an output for outputting a voltage difference between the first and second input voltages;
- and
- a controller including a first input being coupled to the output of the voltage amplifier, a second input being coupled to the external voltage bias, and an output,
- wherein
- the first input of the voltage amplifier is coupled to the common mode, and the second input of the voltage amplifier is coupled to the output of the controller,
- the controller is configured to adjust a voltage at the output of the controller from the external bias based on the voltage difference and to minimize the voltage difference.
Dependencies are inferred from the claim text.