Adjustable MOS resistor
AssigneeNXP B.V.
InventorCord-Heinrich Kohsiek
Life of this patent
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Abstract
A variety of circuits, methods and devices are implemented for providing an adjustable resistance. According to one such implementation an adjustable resistive device includes a metal-oxide semiconductor (MOS) transistor having a gate, a drain, a source, and a body. First circuitry controls a resistance from drain to source by applying a gate voltage that is a function of a variable control input. Second circuitry adjusts a voltage at the body according to a drain voltage and a source voltage, whereby the resistance from drain to source is substantially linear for a given value of the variable control input and over a voltage range.
Claims17
An adjustable resistive device comprising:
- a first metal-oxide semiconductor (MOS) transistor and a second MOS transistor, each having
- a gate,
- a drain,
- a source,
- a body, and
- the first and second MOS transistors having different channel widths respectively for different resistance range;
- and
- first circuitry configured to control, in each of the first and second MOS transistors, a resistance between the drain to the source by applying a gate voltage to the gate that is a function of a variable control input;
- and
- second circuitry configured to adjust, in each of the first and second MOS transistors, a voltage at the body according to a ratio of voltage from the drain to the source, whereby the resistance, in each of the first and second MOS transistors, from the drain to the source is relatively linear for at least three voltage values presented at the variable control input.
An adjustable resistive device comprising:
- a metal-oxide semiconductor (MOS) transistor having
- a gate,
- a drain,
- a source, and
- a body;
- and
- first circuitry configured to control a resistance between the drain to the source by applying a gate voltage to the gate that is a function of a variable control input;
- and
- second circuitry configured to adjust a voltage at the body according to a ratio of voltage from the drain to the source, whereby the resistance from the drain to the source is relatively linear for at least three voltage values presented at the variable control input wherein the linear resistance is effective for voltages within a given voltage range, corresponding to voltages for presentation via a variable control input, and having a frequency component of up to at least 100 Mhz.
An adjustable resistive device comprising:
- a variable control input;
- a plurality of metal-oxide semiconductor (MOS) transistors connected in parallel across a drain and a source of each transistor and each MOS transistor of the plurality having
- a gate,
- a drain,
- a source,
- a channel between the source and the drain, and
- a body;
- and
- first circuitry configured to adjust a voltage at the gate as a function of the variable control input, and
- second circuitry configured to adjust a voltage at the body according to a ratio of voltage from the drain to the source;
- wherein each MOS transistor of the plurality of MOS transistors provides a relatively linear resistance from the drain to the source for a different range of at least three voltage values for the variable control input.
An adjustable resistive device comprising:
- a MOS transistor having a gate, a drain, a source and a body and providing resistive output from drain to source;
- a first resistor connected between the source and the body;
- a second resistor connected between the drain and the body;
- a third resistor connected between the gate and the body;
- a controllable current source;
- and
- a current mirror circuit configured for generating a current through the third resistor that mirrors the controllable current source.
Dependencies are inferred from the claim text.