Radio employing a self calibrating transmitter with reuse of receiver circuitry

• US 6,819,910 B2
• Filed: 03/08/2002
• Issued: 11/16/2004
• Est. Priority Date: 03/08/2002
• Status: Expired due to Fees

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Shi, Hong, Jensen, Henrik T.
• Primary Examiner(s): Nguyen, Duc M.
• Application Number:
  US10/094,495
• Publication Number:
  US 20030171110A1
• Time in Patent Office: 984 Days
• Field of Search: 455/108, 455/114.2, 455/126, 455/115.1, 455/115.3, 455/119, 455/295, 455/296, 455/67.11, 455/67.13, 375/296, 375/298, 375/308, 375/224, 375/279-283, 375/300, 375/301, 332/159, 332/162
• US Class Current: 455/126
• CPC Class Codes: H04B 1/406 with more than one transmission mode, e.g. analog and digital modes

Abstract

A radio includes a self-calibrating transmitter that uses a portion of a receiver section to perform self-calibration. Accordingly, the radio includes a transmitter section, mixer, analog receiver section, calibration switch module, digital receiver section, calibration determination module, and calibration execution module. The transmitter section produces a modulated RF signal from base-band signal and a transmitter local oscillation. The mixer mixes the modulated RF signal with the transmitter local oscillation to produce a base-band representation of the modulated RF signal. In calibration mode, the calibration switch module provides the base-band representation to the receiver section, which processes the representation to produce a 2^nd base-band digital signal. The calibration determination module interprets frequency components of the 2^nd base-band digital signal to produce a calibration signal that compensates for imbalances within the transmitter.

Claims

1. A radio having a self calibrating transmitter, the radio comprises:

transmitter section that produces a modulated radio frequency (RF) signal based on an I component of a baseband signal, an I component of a transmitter local oscillation, a Q component of the baseband signal, and a Q component of the transmitter local oscillation;

mixer operably coupled to mix the modulated RF signal with the I or the Q component of the transmitter local oscillation to produce a baseband representation of the modulated RF signal;

analog receiver section that produces an analog low intermediate frequency (IF) signal based on a received RF signal, an I component of a receiver local oscillation, and a Q component of the receiver local oscillation;

calibration switch module operably coupled to output either the analog low IF signal or the baseband representation of the modulated RF signal in accordance with a switch control signal;

digital receiver section operably coupled to the calibration switch module, wherein the digital receiver section produces a first baseband digital signal from the analog low IF signal and produces a second baseband digital signal from the baseband representation of the modulated RF signal;

calibration determination module operably coupled to produce a calibration signal based on an interpretation of the second baseband digital signal; and

calibration execution module operably coupled to calibrate at least one of;

DC level of the I component of the baseband signal, DC level of the Q component of the baseband signal, gain of the I component of the baseband signal, and gain of the Q component of the baseband signal based on the calibration signal such that the imbalance within the transmitter section is reduced.

2. The radio of claim 1, wherein the calibration determination module further comprises:

processing module; and

memory operably coupled to the processing module, wherein the memory includes operational instructions that cause the processing module to generate the switch control signal when the analog receiver section and digital receiver section are available.

3. The radio of claim 2, wherein the digital receiver section further comprises:

an analog to digital converter module operably coupled to produce a digital I signal and a digital Q signal from the baseband representation of the modulated RF signal;

first filter operably coupled to filter the digital I signal to produce an I component of the second baseband digital signal; and

second filter operably coupled to filter the digital Q signal to produce a Q component of the second baseband digital signal.

4. The radio of claim 3, wherein the memory further comprises operational instructions that cause the processing module to:

provide a first set of coefficients to the first and second filters for calibration of DC offset of the transmitter section; and

provide a second set of coefficients to the first and second filters for calibration of gain offset of the transmitter section.

5. The radio of claim 4, wherein the calibration execution module further comprises at least one of:

an I component DC offset module operably coupled to adjust DC level of the I component of the baseband signal based on the calibration signal;

an I component gain offset module operably coupled to adjust gain of the I component of the baseband signal based on the calibration signal;

a Q component DC offset module operably coupled to adjust DC level of the Q component of the baseband signal based on the calibration signal;

a Q component gain offset module operably coupled to adjust gain of the Q component of the baseband signal based on the calibration signal.

6. The radio of claim 5, wherein the memory further comprises operational instructions that, when the calibration determination module provides the first set of coefficients to the first and second filters, cause the processing module to:

interpret frequency spectrum of the I component of the second baseband digital signal to produce a first frequency spectrum component;

interpret frequency spectrum of the Q component of the second baseband digital signal to produce a second frequency spectrum component; and

compare the first and second frequency spectrum components to produce the calibration signal to adjust the DC offset of at least one of the I and Q components of the baseband signal.

7. The radio of claim 5, wherein the memory further comprises operational instructions that, when the calibration determination module provides the second set of coefficients to the first and second filters, cause the processing module to:

interpret frequency spectrum of the I component of the second baseband digital signal to produce a first frequency spectrum component;

interpret frequency spectrum of the Q component of the second baseband digital signal to produce a second frequency spectrum component; and

compare the first and second frequency spectrum components to produce the calibration signal to adjust the gain offset of at least one of the I and Q components of the baseband signal.

8. A method for transceiving radio frequency (RF) signals including self calibrating transmitting of the RF signals, the method comprises:

producing a modulated radio frequency (RF) signal based on an I component of a baseband signal, an I component of a transmitter local oscillation, a Q component of the baseband signal, and a Q component of the transmitter local oscillation;

mixing the modulated RF signal with the I or the Q component of the transmitter local oscillation to produce a baseband representation of the modulated RF signal;

producing an analog low intermediate frequency (IF) signal based on a received RF signal, an I component of a receiver local oscillation, and a Q component of the receiver local oscillation;

outputting the analog low IF signal or the baseband representation of the modulated RF signal based on a switch control signal;

producing a first baseband digital signal from the analog low IF signal when the analog IF signal is outputted;

producing a second baseband digital signal from the baseband representation of the modulated RF signal when the baseband representation of the modulated RF signal is outputted;

producing a calibration signal based on an interpretation of the second baseband digital signal; and

calibrating at least one of;

DC level of the I component of the baseband signal, DC level of the Q component of the baseband signal, gain of the I component of the baseband signal, and gain of the Q component of the baseband signal based on the calibration signal.

9. The method of claim 8 further comprises:

generating the switch control signal when the radio is in a transmitting mode.

10. The method of claim 9, wherein the producing a second baseband digital signal from the baseband representation of the modulated RF signal further comprises:

analog to digital converting the baseband representation of the modulated RF signal into a digital I signal and a digital Q signal from;

filtering the digital I signal to produce an I component of the second baseband digital signal; and

filtering the digital Q signal to produce a Q component of the second baseband digital signal.

11. The method of claim 10 further comprises:

providing a first set of coefficients to establish first filtering characteristics for the filtering of the digital I signal and the digital Q signal for calibration of DC offset of the transmitter; and

providing a second set of coefficients to establish second filtering characteristics for the filtering of the digital I signal and the digital Q signal for calibration of gain offset of the transmitter section.

12. The method of claim 11, wherein the producing the calibration signal, when providing the first set of coefficients, further comprises:

interpreting frequency spectrum of the I component of the second baseband digital signal to produce a first frequency spectrum component;

interpreting frequency spectrum of the Q component of the second baseband digital signal to produce a second frequency spectrum component; and

comparing the first and second frequency spectrum components to produce the calibration signal to adjust the DC offset of at least one of the I and Q components of the baseband signal.

13. The method of claim 11, wherein the producing the calibration signal, when providing the second set of coefficients, further comprises:

interpreting frequency spectrum of the I component of the second baseband digital signal to produce a first frequency spectrum component;

interpreting frequency spectrum of the Q component of the second baseband digital signal to produce a second frequency spectrum component; and

comparing the first and second frequency spectrum components to produce the calibration signal to adjust the gain offset of at least one of the I and Q components of the baseband signal.

14. An apparatus for transceiving radio frequency (RF) signals including self calibrating transmitting of the RF signals, the apparatus comprises:

processing module; and

memory operably coupled to the processing module, wherein the memory includes operational instructions that cause the processing module to;

produce a modulated radio frequency (RF) signal based on an I component of a baseband signal, an I component of a transmitter local oscillation, a Q component of the baseband signal, and a Q component of the transmitter local oscillation;

mix the modulated RF signal with the I or the Q component of the transmitter local oscillation to produce a baseband representation of the modulated RF signal;

produce an analog low intermediate frequency (IF) signal based on a received RF signal, an I component of a receiver local oscillation, and a Q component of the receiver local oscillation;

output the analog low IF signal or the baseband representation of the modulated RF signal based on a switch control signal;

produce a first baseband digital signal from the analog low IF signal when the analog IF signal is outputted;

produce a second baseband digital signal from the baseband representation of the modulated RF signal when the baseband representation of the modulated RF signal is outputted;

produce a calibration signal based on an interpretation of the second baseband digital signal; and

calibrate at least one of;

DC level of the I component of the baseband signal, DC level of the Q component of the baseband signal, gain of the I component of the baseband signal, and gain of the Q component of the baseband signal based on the calibration signal.

15. The apparatus of claim 14, wherein the memory further comprises operational instructions that cause the processing module to:

generate the switch control signal when the radio is in a transmitting mode.

16. The apparatus of claim 15, wherein the memory further comprises operational instructions that cause the processing module to produce the second baseband digital signal from the baseband representation of the modulated RF signal by:

analog to digital converting the baseband representation of the modulated RF signal into a digital I signal and a digital Q signal from;

filtering the digital I signal to produce an I component of the second baseband digital signal; and

filtering the digital Q signal to produce a Q component of the second baseband digital signal.

17. The apparatus of claim 16, wherein the memory further comprises operational instructions that cause the processing module to:

provide a first set of coefficients to establish first filtering characteristics for the filtering of the digital I signal and the digital Q signal for calibration of DC offset of the transmitter; and

provide a second set of coefficients to establish second filtering characteristics for the filtering of the digital I signal and the digital Q signal for calibration of gain offset of the transmitter section.

18. The apparatus of claim 17, wherein the memory further comprises operational instructions that cause the processing module to produce the calibration signal, when providing the first set of coefficients, by:

interpreting frequency spectrum of the I component of the second baseband digital signal to produce a first frequency spectrum component;

interpreting frequency spectrum of the Q component of the second baseband digital signal to produce a second frequency spectrum component; and

comparing the first and second frequency spectrum components to produce the calibration signal to adjust the DC offset of at least one of the I and Q components of the baseband signal.

19. The apparatus of claim 17, wherein the memory further comprises operational instructions that cause the processing module to produce the calibration signal, when providing the second set of coefficients, by:

interpreting frequency spectrum of the I component of the second baseband digital signal to produce a first frequency spectrum component;

interpreting frequency spectrum of the Q component of the second baseband digital signal to produce a second frequency spectrum component; and

comparing the first and second frequency spectrum components to produce the calibration signal to adjust the gain offset of at least one of the I and Q components of the baseband signal.