Receiver IQ imbalance calibration
A calibration device for use in a radio receiver enables receiver self-calibration and self-correction of inbound RF signals. The calibration device includes an estimation module for receiving a sample digital packet and calculating imbalance parameters as a function of a portion of the sample digital packet. The calibration device further includes a correction module for applying the imbalance parameters to a received digital packet of an inbound RF signal to produce a corrected digital packet. The received digital packet may be a portion of the sample digital packet, the complete sample digital packet or a new packet.
1 . A calibration device for use in a radio receiver, comprising:
an estimation module operably coupled to receive a sample digital packet and to calculate imbalance parameters as a function of a portion of the sample digital packet; and
a correction module operably coupled to receive a received digital packet of an inbound radio frequency (RF) signal and to apply the imbalance parameters to the received digital packet to produce a corrected digital packet.
2 . The calibration device of claim 1 , wherein the estimation module is further operable to accumulate products of in-phase and quadrature-phase components of the portion of the sample digital packet to calculate the imbalance parameters.
3 . The calibration device of claim 1 , wherein the sample digital packet is the received digital packet.
4 . The calibration device of claim 3 , wherein the correction module is further operable to apply the imbalance parameters to a remaining portion of the sample digital packet to produce the corrected digital packet.
5 . The calibration device of claim 3 , wherein the correction module is further operable to apply the imbalance parameters to an entire portion of the sample digital packet to produce the corrected digital packet.
6 . The calibration device of claim 3 , wherein the portion of the sample digital packet includes at least a portion of a short training sequence segment of the sample digital packet.
7 . The calibration device of claim 6 , wherein the estimation module is further operable to detect the sample digital packet at an initial time and perform measurements of the sample digital packet during a measurement period after a waiting period from the initial time to calculate the imbalance parameters.
8 . The calibration device of claim 1 , wherein the sample digital packet is part of a known inbound RF signal.
9 . The calibration device of claim 8 , further comprising:
a memory for storing the imbalance parameters.
10 . The calibration device of claim 1 , wherein the estimation module is distributed between radio circuitry and a processing device, said radio circuitry including dedicated hardware for calculating products of in-phase and quadrature-phase components of the portion of the sample digital packet, said processing device including software executable to calculate the imbalance parameters as a function of the products of the in-phase and quadrature-phase components of the portion of the sample digital packet.
11 . The calibration device of claim 10 , wherein the processing device further includes a calibration control module operable to control calibrations of the receiver.
12 . A radio receiver, comprising:
a low noise amplifier operably coupled to amplify an inbound radio frequency (RF) signal to produce an amplified inbound RF signal;
a down-conversion module operably coupled to convert the amplified inbound RF signal to a low intermediate frequency (IF) signal;
an analog-to-digital converter operably coupled to convert the low IF signal into a digital low IF signal;
a calibration module operably coupled to receive a sample digital packet from the analog-to-digital converter, calculate imbalance parameters as a function of a portion of the sample digital packet and apply the imbalance parameters to a received digital packet of the digital low IF signal to produce a corrected digital packet; and
a digital demodulator operably coupled to convert the corrected digital packet of the digital low IF signal into inbound digital symbols.
13 . The receiver of claim 12 , wherein the calibration module is further operable to accumulate products of signal components of the portion of the sample digital packet to calculate the imbalance parameters.
14 . The receiver of claim 12 , wherein the sample digital packet is the received digital packet.
15 . The receiver of claim 14 , wherein the calibration module is further operable to apply the imbalance parameters to a remaining portion of the sample digital packet to produce the corrected digital packet.
16 . The receiver of claim 14 , wherein the calibration module is further operable to apply the imbalance parameters to an entire portion of the sample digital packet to produce the corrected digital packet.
17 . The receiver of claim 14 , wherein the calibration module is further operable to detect the sample digital packet at an initial time and perform measurements of the sample digital packet during a measurement period after a waiting period from the initial time to calculate the imbalance parameters.
18 . The receiver of claim 12 , wherein the sample digital packet is part of a known inbound RF signal.
19 . The receiver of claim 18 , wherein the known inbound RF signal is produced by a transmitter of a transceiver incorporating the receiver.
20 . The receiver of claim 18 , wherein the known inbound RF signal is produced by a transmitter in the same device as the receiver.
21 . A method for calibrating a receiver to remove imbalance between in-phase and quadrature-phase components of an inbound radio frequency (RF) signal, the method comprising the steps of:
calculating imbalance parameters as a function of a portion of a sample digital packet received at the receiver; and
applying the imbalance parameters to a received digital packet of the inbound RF signal to produce a corrected digital packet
22 . The method of claim 21 , wherein the step of calculating further comprises the step of:
accumulating products of in-phase and quadrature-phase components of the portion of the sample digital packet to calculate the imbalance parameters.
23 . The method of claim 21 , wherein the sample digital packet is the received digital packet, and wherein the step of applying further comprises the step of:
applying the imbalance parameters to a remaining portion of the sample digital packet to produce the corrected digital packet.
24 . The method of claim 21 , wherein the sample digital packet is the received digital packet, and wherein the step of applying further comprises the step of:
applying the imbalance parameters to an entire portion of the sample digital packet to produce the corrected digital packet.
25 . The method of claim 21 , wherein the step of calculating further comprises the steps of:
detecting the sample digital packet at an initial time; and
performing measurements of the sample digital packet during a measurement period after a waiting period from the initial time to calculate the imbalance parameters.
26 . The method of claim 21 , wherein the sample digital packet is part of a known inbound RF signal, and further comprising the step of:
storing the imbalance parameters.