Method and device for calibrating IQ imbalance and DC offset of RF tranceiver

Patent metadata

Field	Value
Publication number	US-9780891-B2
Application number	US-201615229950-A
Country	US
Kind code	B2
Filing date	Aug 5, 2016
Priority date	Mar 3, 2016
Publication date	Oct 3, 2017
Grant date	Oct 3, 2017

Abstract

A method and device for calibrating a DC offset and an I-Q imbalance component of an RF transceiver, the method including inputting a test signal into a transmitter, and converting the test signal into an analogue test signal; converting the analogue test signal using a transmitting mixer; sub-sampling a signal output from the transmitting mixer; and computing a DC offset calibrating constant number and an I-Q imbalance calibrating constant number from a sub-sampled signal.

First claim

What is claimed is:

1. A method for calibrating a DC offset and an I-Q imbalance component of an RF transceiver, the method comprising:
inputting a test signal into a transmitter, and converting the test signal into an analogue test signal;
converting the analogue test signal using a transmitting mixer;
sub-sampling a signal output from the transmitting mixer; and
computing a DC offset calibrating constant number and an I-Q imbalance calibrating constant number from a sub-sampled signal,
wherein a frequency fs of the test signal, a carrier frequency fc and a sub-sampling frequency fss satisfy the following equations [1-1] to [1-3],
kf ss ≦f c ≦( k+ 1) f ss   [1-1]

( k+ ½) f ss ≧f c   [1-2] and

½ f ss ≧f c −kf ss +f s   [1-3],

where k is a constant number.

2. The method according to claim 1 ,
wherein when an output signal of the transmitting mix where the DC offset and I-Q imbalance component are included is based on the following equation 2:
A 1 cos (ω s t+θ 1 ) A 2 cos (ω c t+θ 2 )+ d R A 1 A 2 cos (ω c t+θ 2 )− A 3 sin (ω s t+θ 3 ) A 4 sin (ω c t+θ 4 )+ d I A 3 A 4 sin (ω c t+θ 4 )  (2)

the sub-sampled signal is based on the following equation 3:
A 1 A 2 cos (ω s t+θ 1 ) cos (ω c t−kω ss t+θ 2 )+ d R A 1 A 2 cos (ω c t−kω ss t+θ 2 )− A 3 A 4 sin (ω s t+θ 3 ) sin (ω c t−kω ss t+θ 4 )+ d I A 3 A 4 sin (ω c t−kω ss t+θ 4 )  (3)

where A 1 to A 4 , d R and d I being constant numbers.

3. The method according to claim 2 ,
wherein the DC offset calibrating constant number is computed from (ω c −kω ss ) component of the equation 3, and the I-Q imbalance calibrating constant number is computed from ω s component of the equation 3.

4. The method according to claim 3 ,
further comprising inputting into the transmitter a transmitting signal calibrated with reference to the DC offset calibrating constant number and the I-Q imbalance calibrating constant number.

5. The method according to claim 4 ,
further comprising inputting the calibrated transmitting signal into the transmitter, and when a signal from which the DC offset and the I-Q imbalance component have been removed is output from the transmitter, inputting the signal into a receiver.

6. The method according to claim 5 ,
further comprising computing and calibrating a receiving DC offset and a receiving I-Q imbalance component of an output signal of the receiver generated while going through a receiving path of the receiver.

7. A device for calibrating a DC offset and an I-Q imbalance component of an RF transceiver comprising a transmitter and a receiver, the device comprising:
a transceiving signal error estimator for estimating a transmitting DC offset and a transmitting I-Q imbalance component generated by the transmitter, and for estimating a receiving DC offset and a receiving I-Q imbalance component generated by the receiver;
a transmitting signal compensator for compensating a transmitting signal with reference to the transmitting DC offset and the transmitting I-Q imbalance component estimated in the transceiving signal error estimator; and
a receiving signal compensator for compensating a receiving signal with reference to the receiving DC offset and the receiving I-Q imbalance component estimated in the transceiving signal error estimator,
wherein the transceiving signal error estimator computes the transmitting DC offset and the transmitting I-Q imbalance component from a signal input into the receiver through a single branch of the receiver that bypasses each receiving mixer of the receiver.

8. The device according to claim 7 ,
wherein the transceiving signal error estimator computes the receiving DC offset and the receiving I-Q imbalance component from an output signal of the receiver when a transmitting signal generated from a single branch of the transmitter is input into the receiver.

9. The device according to claim 7 ,
wherein the transceiving signal error estimator computes the receiving DC offset and the receiving I-Q imbalance component from an output signal of the receiver when a transmitting signal for which the transmitting DC offset and the transmitting I-Q imbalance component have been compensated is input to the receiver.

10. The device according to claim 9 ,
wherein the transmitting signal for which the transmitting DC offset and the transmitting I-Q imbalance component have been compensated is obtained by sub-sampling a test signal input into the transmitter.

Assignees

• Electronics & Telecommunications Res Inst

Inventors

• Eo Ik Soo
• Kim Sang-Kyun
• Kim Cheon Soo
• Choi Jang Hong

Classifications

• H04B17/14 Primary

  of the whole transmission and reception path, e.g. self-test loop-back · CPC title

• H04L1/243

  at the transmitter, using a loop-back · CPC title

• H04B17/104

  of other parameters, e.g. DC offset, delay or propagation times · CPC title

• H04B17/0085

  using test signal generators · CPC title