Direct current offset calibration device on the receiving path and direct current offset calibration method thereof

Patent metadata

Field	Value
Publication number	US-12407430-B2
Application number	US-202218082592-A
Country	US
Kind code	B2
Filing date	Dec 16, 2022
Priority date	Dec 5, 2022
Publication date	Sep 2, 2025
Grant date	Sep 2, 2025

Abstract

A direct current (DC) offset calibration device and a method are used to calibrate a DC offset of a unit. The DC offset calibration device includes a signal generation unit, a to-be-calibrated unit, a measurement unit, and a compensation unit. The DC offset calibration method includes: using the to-be-calibrated unit to output a clipped signal resulting from a signal saturation effect; receiving a receiving signal correlated to the clipped signal, the receiving signal including an even harmonic resulting from the clipped signal; measuring a magnitude of the even harmonic to obtain a DC offset adjustment value accordingly; and adjusting the to-be-calibrated unit according to the DC offset adjustment value to calibrate the DC offset.

First claim

What is claimed is:

1. A direct current (DC) offset calibration device comprising:
a signal generation unit configured to provide a first signal;
a to-be-calibrated unit coupled to the signal generation unit, the to-be-calibrated unit being configured to receive the first signal and output a second signal accordingly, wherein the second signal is a clipped signal;
a measurement unit coupled to the to-be-calibrated unit, the measurement unit being configured to receive a receiving signal correlated to the second signal, the receiving signal comprising an even harmonic resulted from the clipped signal, the measurement unit being configured to measure a magnitude of the even harmonic; and
a compensation unit coupled to the measurement unit and the to-be-calibrated unit, the compensation unit being configured to compute and obtain a DC offset adjustment value according to the magnitude of the even harmonic, and to adjust the to-be-calibrated unit according to the DC offset adjustment value.

2. The DC offset calibration device of claim 1 , wherein the signal generation unit comprises:
a signal generator configured to generate a reference signal; and
a signal amplifier coupled to the signal generator, the signal amplifier being configured to receive the reference signal and amplify the reference signal to output the first signal.

3. The DC offset calibration device of claim 2 , wherein:
the signal generator comprises a sine wave generator and the reference signal comprises a sine wave; and
the signal amplifier comprises a variable gain amplifier.

4. The DC offset calibration device of claim 1 , wherein the receiving signal is the second signal.

5. The DC offset calibration device of claim 1 , wherein:
by a transmitting antenna, the second signal is transmitted to generate a first wireless signal; and
by a receiving antenna, a second wireless signal correlated to the first wireless signal is received and the receiving signal is generated according to the second wireless signal.

6. The DC offset calibration device of claim 1 , wherein the measurement unit comprises:
an analog-to-digital converter configured to generate a digital signal according to the receiving signal; and
a harmonic measurement circuit coupled to the analog-to-digital converter, and configured to obtain the magnitude of the even harmonic according to the digital signal.

7. The DC offset calibration device of claim 1 , wherein the to-be-calibrated unit comprises:
a to-be-calibrated circuit; and
a DC offset calibration circuit coupled to the to-be-calibrated circuit, the DC offset calibration circuit being configured to adjust a DC level of the to-be-calibrated circuit according to the DC offset adjustment value.

8. The DC offset calibration device of claim 7 , wherein:
the DC offset calibration circuit comprises a variable resistor, and the DC offset calibration circuit being configured to change a resistance of the variable resistor according to the DC offset adjustment value, so as to adjust the DC level of the to-be-calibrated circuit.

9. The DC offset calibration device of claim 7 , wherein:
the DC offset calibration circuit comprises a DC compensation circuit configured to provide a calibration value according to the DC offset adjustment value to compensate for the DC level of the to-be-calibrated circuit.

10. The DC offset calibration device of claim 7 , wherein the to-be-calibrated circuit comprises a digital-to-analog converter, an analog-to-digital converter, a mixer, a power amplifier, a low-noise amplifier, and/or an operational amplifier.

11. The DC offset calibration device of claim 10 , wherein the power amplifier comprises a variable gain amplifier (VGA) and/or a transconductance amplifier.

12. The DC offset calibration device of claim 1 , wherein the signal generation unit and the to-be-calibrated unit are arranged in a transmission path, and the measurement unit is arranged in a reception path.

13. The DC offset calibration device of claim 1 , wherein the compensation unit is configured to adjust the to-be-calibrated unit according to the DC offset adjustment value, so as to reduce a magnitude of a next even harmonic measured by the measurement unit.

14. The DC offset calibration device of claim 13 , wherein the compensation unit is configured to adjust the to-be-calibrated unit according to the DC offset adjustment value, such that the magnitude of the next even harmonic measured by the measurement unit is equal to or less than a predetermined value.

15. The DC offset calibration device of claim 14 , wherein:
the predetermined value is correlated to a sensitivity of the measurement unit, or to a system specification of a communication circuit where the DC offset calibration device is used; and
the compensation unit comprises a memory configured to store the DC offset adjustment value and the predetermined value.

16. A DC offset calibration method, used to calibrate a DC offset of a to-be-calibrated unit, the method comprising:
the to-be-calibrated unit outputting a second signal, wherein the second signal is clipped due to a signal saturation effect of the to-be-calibrated unit, and wherein the second signal is clipped asymmetrically further due to the DC offset of the to-be-calibrated unit;
receiving a receiving signal correlated to the second signal, wherein the receiving signal includes an even harmonic resulting from asymmetrical clipping;
measuring a magnitude of the even harmonic;
computing a DC offset adjustment value according to the magnitude of the even harmonic; and
adjusting the to-be-calibrated unit according to the DC offset adjustment value to calibrate the DC offset.

17. The method of claim 16 , further comprising:
generating a reference signal;
amplifying the reference signal to output a first signal; and
by the to-be-calibrated unit, receiving the first signal and outputting the second signal accordingly.

18. The method of claim 16 , further comprising:
by a transmitting antenna, transmitting the second signal to generate a first wireless signal; and
by a receiving antenna, receiving a second wireless signal correlated to the first wireless signal and generating the receiving signal according to the second wireless signal.

19. The method of claim 16 , wherein step of adjusting the to-be-calibrated unit according to the DC offset adjustment value comprises:
varying a resistance of a variable resistor according to the DC offset adjustment value to adjust a DC level of the to-be-calibrated unit; or
providing a calibration value according to the DC offset adjustment value to compensate for the DC level of the to-be-calibrated unit.

20. The method of claim 16 , wherein step of adjusting the to-be-calibrated unit according to the DC offset adjustment value comprises:
adjusting the to-be-calibrated unit according to the DC offset adjustment value to, so as to reduce a magnitude of a next even harmonic measured by the measurement unit until the magnitude of the next even harmonic measured by the measurement unit is equal to or less than a predetermined value.

Assignees

• Richwave Technology Corp

Inventors

• Yang Shun-Pin

Classifications

• H04B17/0085

  using test signal generators · CPC title

• H03D3/008

  Compensating DC offsets · CPC title

• H03D2200/0047

  Offset of DC voltage or frequency · CPC title

• H04B2001/305

  using DC offset compensation techniques · CPC title

• H04L25/06

  DC level restoring means; Bias distortion correction {; Decision circuits providing symbol by symbol detection} · CPC title