Methods and apparatus to determine a bias current of an amplifier
AssigneeTexas Instruments Incorporated
InventorIchiro Itoi
Life of this patent
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Abstract
An example apparatus includes: an amplifier having an input and an output; feedback circuitry having a first terminal and a second terminal, the first terminal of the feedback circuitry directly connected to the input of the amplifier, the second terminal of the feedback circuitry directly connected to the output of the amplifier; voltage divider circuitry having a first terminal and a second terminal, the first terminal of the voltage divider circuitry directly connected to the output of the amplifier; and a capacitor having a terminal directly connected to the second terminal of the voltage divider circuitry.
Claims24
An apparatus comprising:
- an amplifier having an input and an output;
- feedback circuitry having a first terminal and a second terminal, the first terminal of the feedback circuitry directly connected to the input of the amplifier, the second terminal of the feedback circuitry directly connected to the output of the amplifier;
- voltage divider circuitry having a first terminal and a second terminal, the first terminal of the voltage divider circuitry directly connected to the output of the amplifier;
- a capacitor having a first terminal directly connected to the second terminal of the voltage divider circuitry;
- and
- charge injection circuitry coupled to the first terminal of the capacitor and to the second terminal of the voltage divider circuitry.
A system comprising:
- a first amplifier having an input;
- a second amplifier having an inverting input and an output;
- feedback circuitry having a first terminal and a second terminal, the first terminal of the feedback circuitry coupled to the output of the second amplifier, the second terminal of the feedback circuitry coupled to the inverting input of the second amplifier;
- voltage divider circuitry having a first terminal and a second terminal, the first terminal of the voltage divider circuitry coupled to the output of the second amplifier;
- a capacitor having a first terminal and a second terminal, the first terminal of the capacitor coupled to the input of the first amplifier, the second terminal of the capacitor coupled to the second terminal of the voltage divider circuitry;
- and
- charge injection circuitry coupled to the second terminal of the capacitor and the second terminal of the voltage divider circuitry.
A method comprising:
- measuring, by sampling circuitry, a voltage at an output of a first amplifier;
- determining, by voltage monitor circuitry, a change in the voltage at the output of the first amplifier over time;
- and
- calculating, by current determination circuitry, a bias current of a second amplifier based on the change in the voltage at the output of the first amplifier over time, a gain of voltage divider circuitry, and a capacitance of integration circuitry.
A method comprising:
- determining, by sampling circuitry, a voltage at an output of a first amplifier;
- determining, by voltage monitor circuitry, a change in the voltage at the output of the first amplifier over time;
- and
- determining, by current determination circuitry, a bias current of a second amplifier based on the change in the voltage at the output of the first amplifier over time, a gain of voltage divider circuitry, and a capacitance of integration circuitry.
Dependencies are inferred from the claim text.