Digital-to-analog converter and operation method thereof

Patent metadata

Field	Value
Publication number	US-2025202496-A1
Application number	US-202318391683-A
Country	US
Kind code	A1
Filing date	Dec 21, 2023
Priority date	Dec 13, 2023
Publication date	Jun 19, 2025
Grant date	—

Abstract

A digital-to-analog converter (DAC) and an operation method thereof are provided. The DAC includes a first operational amplifier (OPA), a second OPA, a resistor circuit, first switches, second switches, a first voltage shift circuit and a second voltage shift circuit. The first OPA outputs a first operating voltage. The second OPA outputs a second operating voltage. First terminals of the first switches receive the first operating voltage. First terminals of the second switches receive the second operating voltage. Second terminals of the first switches and the second switches are coupled to the resistor circuit. The first switches and the second switches perform switching operations in response to digital values. The first voltage shift circuit provides a first compensation voltage to the first OPA. The second voltage shift circuit provides a second compensation voltage to the second OPA.

First claim

What is claimed is:

1 . A digital-to-analog converter, comprising:
a first operational amplifier, configured to receive a first reference voltage through a non-inverting input terminal of the first operational amplifier and output a first operating voltage according to the first reference voltage; a second operational amplifier, configured to receive a second reference voltage through a non-inverting input terminal of the second operational amplifier and output a second operating voltage according to the second reference voltage; a resistance circuit, comprising a plurality of input resistors, wherein input terminals of the plurality of input resistors are coupled to an output terminal of the digital-to-analog converter; a plurality of first switches, first terminals of the plurality of first switches receive the first operating voltage, second terminals of the plurality of first switches are correspondingly coupled to second terminals of the input resistors; a plurality of second switches, first terminals of the plurality of second switches receive the second operating voltage, second terminals of the plurality of second switches are correspondingly coupled to the second terminals of the input resistors, wherein the plurality of first switches and the plurality of second switches perform a switching operation in response to a digital value; a first voltage shift circuit, coupled between an inverting input terminal of the first operational amplifier and the resistance circuit, and configured to provide a first compensation voltage to the inverting input terminal of the first operational amplifier; and a second voltage shift circuit, coupled between an inverting input terminal of the second operational amplifier and the resistance circuit, and configured to provide a second compensation voltage to the inverting input terminal of the second operational amplifier, wherein the first compensation voltage is calibrated to adjust an output range of the digital-to-analog converter, wherein the first voltage shift circuit adjusts a conversion linearity of the digital-to-analog converter.

2 . The digital-to-analog converter of claim 1 , wherein the voltage shift circuit comprises:
a first voltage shifter, an output terminal of the first voltage shifter is coupled to the inverting input terminal of the first operational amplifier; and a plurality of first control switches, first terminals of the plurality of first control switches are coupled to an input terminal of the first voltage shifter, second terminals of the plurality of first control switches are correspondingly coupled to the second terminals of the input resistors.

3 . The digital-to-analog converter of claim 2 , wherein the first voltage shifter shifts an input voltage on the input terminal of the first voltage shifter to generate the first compensation voltage, and outputs the first compensation voltage through an output terminal of the first voltage shifter.

4 . The digital-to-analog converter of claim 3 , wherein a voltage value of the first compensation voltage is lower than a voltage value of the input voltage.

5 . The digital-to-analog converter of claim 3 , wherein the first voltage shifter comprises:
a transistor, a first terminal of the transistor is coupled to a reference high voltage, a control terminal of the transistor is coupled to the input terminal of the first voltage shifter to receive the input voltage, a second terminal of the transistor is coupled to the output terminal of the first voltage shifter; and a current source, coupled to the second terminal of the transistor, wherein the current source adjusts a shifting voltage value of the first voltage shifter according to a calibrating signal.

6 . The digital-to-analog converter of claim 3 , wherein the first voltage shifter comprises:
a first transistor, a first terminal of the first transistor is coupled to a reference high voltage, a control terminal of the first transistor is coupled to the input terminal of the first voltage shifter to receive the input voltage; a first current source, coupled to the second terminal of the first transistor; a second transistor, a first terminal of the second transistor is coupled to a reference high voltage, a control terminal of the second transistor is coupled to the second terminal of the first transistor, a second terminal of the second transistor is coupled to the output terminal of the first voltage shifter; and a second current source, coupled to the second terminal of the second transistor, wherein the first current source and the second current source adjust a shifting voltage value of the first voltage shifter according to a calibrating signal.

7 . The digital-to-analog converter of claim 1 , wherein the second voltage shift circuit comprises:
a second voltage shifter, an output terminal of the second voltage shifter is coupled to the inverting input terminal of the second operational amplifier; and a plurality of second control switches, first terminals of the plurality of second control switches are coupled to an input terminal of the second voltage shifter, second terminals of the plurality of second control switches are correspondingly coupled to the second terminals of the input resistors.

8 . The digital-to-analog converter of claim 7 , wherein the second voltage shifter shifts an input voltage on the input terminal of the second voltage shifter to generate the second compensation voltage, and outputs the second compensation voltage through an output terminal of the second voltage shifter.

9 . The digital-to-analog converter of claim 8 , wherein a voltage value of the second compensation voltage is higher than a voltage value of the input voltage.

10 . The digital-to-analog converter of claim 8 , wherein
a current source; and a transistor, a first terminal of the transistor is coupled to the current source and the output terminal of the second voltage shifter, a control terminal of the transistor is coupled to the input terminal of the second voltage shifter to receive the input voltage, a second terminal of the transistor is coupled to a reference low voltage; and wherein the current source adjusts a shifting voltage value of the second voltage shifter according to a calibrating signal.

11 . The digital-to-analog converter of claim 1 , wherein the first voltage shift circuit comprises:
a plurality of first voltage shifters, input terminals of the plurality of first voltage shifters are correspondingly coupled to the second terminals of the input resistors; and a plurality of first control switches, first terminals of the plurality first control switches are correspondingly coupled to the output terminals of the plurality of first voltage shifters, second terminals of the plurality first control switches are coupled to the inverting input terminal of the first operational amplifier.

12 . The digital-to-analog converter of claim 11 , wherein:
the digital-to-analog converter further comprises a control circuit, the plurality of first voltage shifters comprise a 0th bit voltage shifter to an (n−1)th bit voltage shifter, the plurality of first control switches comprise a 0th bit control switch to an (n−1)th bit control switch, the control circuit turns on the 0th bit control switch and turns off remaining first control switches, and receives a first voltage value on a first node of the resistance circuit, and the control circuit turns on a first bit control switch and turns off remaining first control switches, and receives a second voltage value on the first node of the resistance circuit.

13 . The digital-to-analog convert

Assignees

• Ind Tech Res Inst

Inventors

• Chung Yung-Hui
• Tseng Yun-Heng
• Chen Bo-Wei

Classifications

• H03M1/66

  Digital/analogue converters ({H03M1/001 – } H03M1/10 take precedence) · CPC title

• H03M1/06

  Continuously compensating for, or preventing, undesired influence of physical parameters (periodically, {e.g. by using stored correction values,} H03M1/10) · CPC title

• H03M1/78

  using ladder network · CPC title

• H03M1/742

  using current sources as quantisation value generators · CPC title

• H03M1/785

  using resistors, i.e. R-2R ladders · CPC title