Offset drift compensation

Patent metadata

Field	Value
Publication number	US-10530308-B2
Application number	US-201815934467-A
Country	US
Kind code	B2
Filing date	Mar 23, 2018
Priority date	Mar 23, 2018
Publication date	Jan 7, 2020
Grant date	Jan 7, 2020

Abstract

An offset drift compensation circuit for correcting offset drift that changes with temperature. In one example, offset drift compensation circuit includes a low temperature offset compensation circuit and a high temperature offset circuit. The low temperature offset compensation circuit is configured to compensate for drift in offset at a first rate below a selected temperature. The high temperature offset compensation circuit is configured to compensate for drift in offset at a second rate above the selected temperature. The first rate is different from the second rate.

First claim

What is claimed is:

1. An amplifier, comprising:
an amplification stage; and
an offset drift compensation circuit coupled to the amplification stage, the offset drift compensation circuit configured to provide an offset compensation current to the amplification stage;
wherein:
the offset compensation current cancels offset voltage generated by the amplification stage as a result of change in temperature;
the offset compensation circuit provides a first offset compensation current to an output of the amplification stage when the temperature is above a fixed temperature; and
the offset compensation circuit provides a second offset compensation current to the output of the amplification stage when the temperature is below the fixed temperature.

2. The amplifier of claim 1 , wherein the offset drift compensation circuit comprises a low temperature offset compensation circuit configured to:
generate the second offset compensation current starting at a first temperature that is less than or equal to the fixed temperature; and
generate a fixed offset compensation current responsive to temperature above the first temperature.

3. The amplifier of claim 2 , wherein the low temperature offset compensation circuit comprises:
a bandgap voltage circuit; and
a base-emitter voltage circuit;
wherein:
current flows through the bandgap voltage circuit to the base-emitter voltage circuit; and
current flowing through the bandgap voltage circuit is set to determine the first temperature.

4. The amplifier of claim 2 , wherein the offset drift compensation circuit comprises a high temperature offset compensation circuit configured to:
generate the first offset compensation current starting at a second temperature that is higher than or equal to the fixed temperature; and
generate the fixed offset compensation current responsive to temperature below the second temperature.

5. The amplifier of claim 4 , wherein the high temperature offset compensation circuit comprises:
a bandgap voltage circuit; and
a base-emitter voltage circuit;
wherein:
current flows through the base-emitter voltage circuit to the bandgap voltage circuit; and
current flowing through the bandgap voltage circuit is set to determine the second temperature.

6. The amplifier of claim 1 , wherein the offset compensation circuity comprises:
a first current output digital-to-analog converter; and
a second current output digital-to-analog converter.

7. The amplifier of claim 4 , wherein the offset drift compensation circuit comprises a current mirror coupled to the amplification stage, the low temperature offset circuit, and the high temperature offset circuit.

8. An asymmetric offset drift compensation circuit, comprising:
a low temperature offset compensation circuit comprising:
a first bandgap voltage circuit; and
a first base-emitter voltage circuit;
wherein
current flows through the first bandgap voltage circuit to the first base-emitter voltage circuit; and
current flowing through the first bandgap voltage circuit is set to cause the low temperature offset compensation circuit to generate a first offset compensation ramp voltage starting at a first temperature; and

a high temperature offset compensation circuit comprising:
a second bandgap voltage circuit; and
a second base-emitter voltage circuit;
wherein
current flows through the second base-emitter voltage circuit to the second bandgap voltage circuit; and
current flowing through the second bandgap voltage circuit is set to cause the high temperature offset compensation circuit to generate a second offset compensation ramp voltage starting at a second temperature.

Assignees

• Texas Instruments Inc

Inventors

• Balasubramanian Shyamsunder
• Tan Wenxiao
• Garg Mayank
• Tanaka Toru

Classifications

• H03F2200/91

  the amplifier has a current mode topology · CPC title

• H03F2200/528

  the temperature dependence being controlled by referencing to the band gap · CPC title

• H03F3/04

  with semiconductor devices only · CPC title

• H03F2200/447

  the amplifier being protected to temperature influence · CPC title

• H03M1/742

  using current sources as quantisation value generators · CPC title