Quadrature receiver sampling architecture

• US 20070053468A1
• Filed: 11/06/2006
• Published: 03/08/2007
• Est. Priority Date: 05/17/2002
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Jaffe, Steven, Yu, Tommy, Krafft, Stephen
• Granted Patent: US 7,596,189 B2
• Time in Patent Office: Days
• US Class Current: 375/332
• CPC Class Codes: H04L 27/00 Modulated-carrier systems

Abstract

Quadrature receiver sampling architecture. A signal ADC performs analog to digital conversion for both I and Q streams. An analog MUX selects the appropriate I and the Q baseband analog input streams for input to the ADC at the appropriate time. A digital filter may also be employed to compensate for any introduced delay between the samples of the I and Q channel when seeking to recover the symbols that have been transmitted to a communication receiver that employs this quadrature receiver architecture and/or signal processing. In one embodiment, if an ADC is clocked at a rate of substantially twice the sample rate of the I and Q channels, there will be a one-half sample clock delay between the digital I and digital Q data at the output of the ADC. This delay is then removed before the demodulator processes the input signals to recover the transmitted symbols.

Claims

1. A communication device, comprising:

an analog to digital converter (ADC) that is operable to;

alternatively receive an analog I stream and an analog Q stream; and

sample the alternatively received analog I stream and analog Q stream thereby generating a digital stream that includes alternating digital I information and digital Q information; and

a digital signal processor (DSP), coupled to the ADC, that is operable to process the digital stream to compensate for an alternative analog to digital conversion introduced effect thereon.

2. The communication device of claim 1, wherein:

the alternative analog to digital conversion introduced effect is a delay between the digital I information and digital Q information within the digital stream that is introduced by using a single ADC to perform the sampling of the alternatively received analog I stream and analog Q stream.

3. The communication device of claim 1, wherein:

the DSP is operable to perform at least one of decimation, de-rotation, and delay compensation on the digital stream that includes alternating digital I information and digital Q information to compensate for the alternative analog to digital conversion introduced effect.

4. The communication device of claim 1, further comprising:

a multiplexor (MUX) that is operable to provide the analog I stream and the analog Q stream alternatively to the ADC.

5. The communication device of claim 1, further comprising:

a multiplexor (MUX) that is operable to provide the analog I stream and the analog Q stream alternatively to the ADC; and

wherein;

the ADC is clocked at a first frequency; and

the MUX is clocked at a second frequency that is one-half of the first frequency.

6. The communication device of claim 1, further comprising:

a de-multiplexor (DE-MUX), interposed between the ADC and the DSP, that is operable alternatively to extract a digital I stream and a digital Q stream from the digital stream.

7. The communication device of claim 1, further comprising:

a de-multiplexor (DE-MUX), interposed between the ADC and the DSP, that is operable alternatively to extract a digital I stream and a digital Q stream from the digital stream; and

wherein;

the ADC is clocked at a first frequency; and

the DE-MUX is clocked at a second frequency that is one-half of the first frequency.

8. The communication device of claim 1, wherein:

the communication device includes an analog front end (AFE) and a digital processing unit (DPU);

the AFE includes the ADC; and

the DPU includes the DSP.

9. The communication device of claim 1, wherein:

the communication device is a wireless communication device that is implemented within a wireless communication system.

10. The communication device of claim 1, wherein:

the communication device is at least one of a base station communication device, a mobile communication device, a set top box, a tower communication device, and an HDTV set top box communication device.

11. A communication device, comprising:

a multiplexor (MUX) that is operable to;

receive an analog I stream;

receive an analog Q stream; and

output an analog stream that alternatively includes the analog I stream and the analog Q stream;

an analog to digital converter (ADC) that is operable to;

receive the an analog stream; and

sample the analog stream thereby generating a digital stream that includes alternating digital I information and digital Q information;

a de-multiplexor (DE-MUX) that is operable alternatively to extract a digital I stream and a digital Q stream from the digital stream; and

a digital signal processor (DSP) that is operable to process at least one of the digital I stream and the digital Q stream to compensate for an alternative analog to digital conversion introduced effect thereon.

12. The communication device of claim 11, further comprising:

a sample and hold module, interposed between the MUX and the ADC, that is operable to process the analog stream to ensure proper sampling of the analog stream by the ADC.

13. The communication device of claim 11, wherein:

the alternative analog to digital conversion introduced effect is a delay between the digital I stream and the digital Q stream introduced by using a single ADC to perform the sampling of the analog stream that includes alternating digital I information and digital Q information.

14. The communication device of claim 11, wherein:

the DSP is operable to perform at least one of decimation, de-rotation, and delay compensation on at least one of the digital I stream and the digital Q stream to compensate for the alternative analog to digital conversion introduced effect.

15. The communication device of claim 11, wherein:

the ADC and the MUX are clocked at a first frequency; and

the DE-MUX is clocked at a second frequency that is one-half of the first frequency.

16. The communication device of claim 11, further comprising:

a sample and hold module, interposed between the MUX and the ADC, that is operable to process the analog stream to ensure proper sampling of the analog stream by the ADC; and

wherein;

the ADC and the sample and hold module are clocked at a first frequency; and

the DE-MUX and the MUX are clocked at a second frequency that is one-half of the first frequency.

17. The communication device of claim 11, wherein:

the communication device is a wireless communication device that is implemented within a wireless communication system.

18. A method, comprising:

receiving an analog I stream;

receiving an analog Q stream; and

forming and outputting an analog stream that alternatively includes the analog I stream and the analog Q stream;

digitally sampling the analog stream thereby generating a digital stream that includes alternating digital I information and digital Q information;

alternatively extracting a digital I stream and a digital Q stream from the digital stream; and

processing at least one of the digital I stream and the digital Q stream to compensate for an alternative analog to digital conversion introduced effect thereon.

19. The method of claim 18, wherein:

the alternative analog to digital conversion introduced effect is a delay between the digital I stream and the digital Q stream introduced by using a single ADC to perform the digital sampling of the analog stream that includes alternating digital I information and digital Q information.

20. The method of claim 18, wherein:

the method is performed within a communication device; and

the communication device is a wireless communication device that is implemented within a wireless communication system.