High voltage input circuit for a differential amplifier
AssigneeTexas Instruments Incorporated
InventorsSteven Graham Brantley, Vadim Valerievich Ivanov
Life of this patent
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Abstract
A differential input circuit (FIG. 3A) is disclosed. The circuit includes a first input terminal (drain of 310) and a second input terminal (drain of 312). A first input transistor (310) has a first control terminal and has a current path coupled to the first input terminal. A second input transistor (312) has a second control terminal and has a current path coupled to the second input terminal. A third transistor (306) has a third control terminal and has a current path between a first differential input terminal (Vin+) and the first control terminal. A fourth transistor (308) has a fourth control terminal and has a current path between a second differential input terminal (Vin−) and the second control terminal.
Claims20
A differential input circuit, comprising:
- a first input terminal;
- a second input terminal;
- a first input transistor having a first control terminal and having a current path coupled to the first input terminal;
- a second input transistor having a second control terminal and having a current path coupled to the second input terminal;
- a third transistor having a third control terminal and having a current path between a first differential input terminal and the first control terminal;
- a fourth transistor having a fourth control terminal and having a current path between a second differential input terminal and the second control terminal;
- and
- a first diode coupled between the first control terminal and the third control terminal;
- and
- a second diode coupled between the second control terminal and the fourth control terminal.
A method of operating a differential circuit, comprising:
- applying a first input voltage to a first control terminal of a first input transistor through a current path of a first switching transistor;
- applying a second input voltage to a second control terminal of a second input transistor through a current path of a second switching transistor;
- applying a control voltage to third and fourth control terminals of the first and second switching transistors, respectively;
- and
- turning off, with at least one of a first diode and a second diode, at least one of the first and second switching transistors when a difference between the first and second input voltages exceeds a predetermined value, the first diode being coupled between the first control terminal and the third control terminal, and the second diode being coupled between the second control terminal and the fourth control terminal.
A differential input circuit, comprising:
- a first terminal;
- a second terminal;
- a first input transistor having a first control terminal and having a current path formed between second and third terminals of the first input transistor, the second and third terminals of the first input transistor being different than the first control terminal, the first current path coupled to the first terminal;
- a second input transistor having a second control terminal and having a current path formed between fifth and sixth terminals of the second input transistor, the fifth and sixth terminals of the second input transistor being different than the second control terminal, the second current path coupled to the second terminal;
- a third transistor having a third control terminal coupled to the current path of the first input transistor and having a current path coupled between a first differential input terminal and the first control terminal;
- a fourth transistor having a fourth control terminal coupled to the current path of the second input transistor and having a current path coupled between a second differential input terminal and the second control terminal;
- a first diode coupled between the first control terminal and the third control terminal;
- and
- a second diode coupled between the second control terminal and the fourth control terminal.
Dependencies are inferred from the claim text.