Receiver architectures utilizing coarse analog tuning and associated methods

• US 7,340,230 B2
• Filed: 04/14/2003
• Issued: 03/04/2008
• Est. Priority Date: 04/14/2003
• Status: Active Grant

• Current Assignee: Silicon Laboratories Incorporated
• Original Assignee: Silicon Laboratories Incorporated
• Inventors: Krone, Andrew W., Khoini-Poorfard, Ramin
• Primary Examiner(s): Maung; Nay
• Assistant Examiner(s): Chan; Richard
• Application Number:
  US10/412,963
• Publication Number:
  US 20040205820A1
• Time in Patent Office: 1,786 Days
• Field of Search: 445/132, 445/133, 445/313, 445/318, 445/323, 445/334, 445/427, 445/12.1, 445/3.02, 375/344
• US Class Current: 455/132
• CPC Class Codes: H03D 3/006 by sampling the oscillations and further processing the samples, e.g. by computing techniques H03D3/007 takes precedence
• CPC Class Codes: H03D 3/007 by converting the oscillations into two quadrature related signals H03D3/245 takes precedence
• CPC Class Codes: H03L 7/18 using a frequency divider or counter in the loop H03L7/20, H03L7/22 take precedence
• CPC Class Codes: H04H 40/90 specially adapted for satellite broadcast receiving
• CPC Class Codes: H04N 21/426 Internal components of the client ; Characteristics thereof H04N5/44 takes precedence
• CPC Class Codes: H04N 21/4263 involving specific tuning arrangements, e.g. two tuners
• CPC Class Codes: H04N 5/4446 IF amplifier circuits specially adapted for B&W TV RF amplifiers in general H03F3/189
• CPC Class Codes: H04N 5/50 Tuning indicators; Automatic tuning control
• CPC Class Codes: H04N 7/20 Adaptations for transmission via a GHz frequency band, e.g. via satellite

Abstract

Receiver architectures and associated methods are disclosed that provide initial analog coarse tuning of desired channels within a received signal spectrum, such as a set-top box signal spectrum for satellite communications. These architectures provide significant advantages over prior direct down-conversion (DDC) architectures and low intermediate-frequency (IF) architectures, particularly where two tuners are desired on the same integrated circuit. Rather than using a low-IF frequency or directly converting the desired channel frequency to DC, initial coarse tuning provided by analog coarse tuning circuitry allows for a conversion to a frequency range around DC. This coarse tuning circuitry can be implemented, for example, using a large-step local oscillator (LO) that provides a coarse tune analog mixing signal. Once mixed down, the desired channel may then be fine-tuned through digital processing, such as through the use of a wide-band analog-to-digital converter (ADC) or a narrow-band tunable bandpass ADC.

Claims

1. A receiver for tuning a channel within a signal spectrum, comprising:

local oscillator (LO) circuitry having a channel selection signal as an input and having a coarse-tune analog mixing signal as an output, the output mixing signal being selected from a plurality of predetermined output mixing signals depending upon a desired channel to be tuned;

analog coarse tune circuitry having the coarse-tune analog mixing signal as an input and having a signal spectrum as an input, the signal spectrum including a plurality of channels within a frequency range, and the analog coarse tune circuitry being configured to use the coarse-tune analog mixing signal to output a coarsely tuned signal spectrum such that the desired channel within the coarsely tuned signal spectrum is mixed down to a variable location within a frequency range around DC, the variable location being dependent upon the desired channel and the selected coarse-tune analog mixing signal; and

digital fine tune circuitry having the coarsely tuned signal spectrum as an input and having as an output digital baseband signals for the desired channel;

wherein the LO circuitry comprises phase-lock-loop (PLL) circuitry including a phase detector and a controlled oscillator, the phase detector receiving a first signal representative of a reference frequency, receiving a second signal representative of an output frequency of the controlled oscillator, and generating at least one control signal to adjust the output frequency of the controlled oscillator; and

wherein the LO circuitry further comprises control circuitry configured to receive a channel selection signal and to control divider circuitry that provides the first and second signals to the phase detector based upon divided versions of the reference frequency and the output of the controlled oscillator, the control circuitry acting to select the coarse-tune analog mixing signal output by the PLL circuitry.

2. The receiver of claim 1 wherein the signal spectrum comprises a channel signal spectrum from satellite communications, the satellite channel signal spectrum comprising a plurality of transponder channels with each transponder channel including a plurality of program channels.

3. The receiver of claim 1, wherein the frequency range of the signal spectrum is organized into a plurality of frequency bins and wherein at least one coarse-tune analog mixing signal is associated with each frequency bin.

4. The receiver of claim 3, wherein the analog mixing signal selected for output by the LO circuitry is an analog mixing signal associated with the bin within which the desired channel falls.

5. The receiver of claim 4,

wherein a different analog mixing signal is selected by the LO circuitry if the desired channel overlaps the analog mixing signal associated with the bin within which the desired channel falls.

6. The receiver of claim 3, further comprising configuring the frequency bins not to overlap.

7. The receiver of claim 3, farther comprising configuring the frequency bins such that one or more of the frequency bins overlap in frequency ranges.

8. The receiver of claim 7,

further comprising organizing the overlapping frequency bins as two sets of non-overlapping frequency bins, the first set overlapping the second set.

9. The receiver of claim 1, wherein the digital fine tune circuitry comprises a wide-band analog-to-digital converter having the coarsely tuned signal spectrum as an input and having digital signals as an output, and further comprising a tunable digital filter configured to tune the desired channel.

10. The receiver of claim 1, wherein the digital fine tune circuitry comprises a narrow-band tunable bandpass analog-to-digital converter configured to tune the desired channel and to convert the coarsely tuned signal spectrum to digital signals, and further comprising a tunable digital filter to further tune the desired channel.

11. The receiver of claim 1, wherein the controlled oscillator utilizes an RC-based resonant structure.

12. A satellite set-top box for tuning a program channel within a satellite signal spectrum, comprising:

a receiver configured to receive a satellite signal spectrum including a plurality of transponder channels and to tune a transponder channel within the signal spectrum, each transponder channel including a plurality of program channels, comprising;

local oscillator (LO) circuitry having a channel selection signal as an input and having a coarse-tune analog mixing signal as an output, the output mixing signal being selected from a plurality of predetermined output mixing signals depending upon a desired channel to be tuned;

analog coarse tune circuitry having the coarse-tune analog mixing signal as an input and having a signal spectrum as an input, the signal spectrum including a plurality of channels within a frequency range, and the analog coarse tune circuitry being configured to use the coarse-tune analog mixing signal to output a coarsely tuned signal spectrum such that the desired channel within the coarsely tuned signal spectrum is mixed down to a variable location within a frequency range around DC, the variable location being dependent upon the desired channel and the selected coarse-tune analog mixing signal; and

digital fine tune circuitry having the coarsely tuned signal spectrum as an input and having as an output digital baseband signals for the desired channel; and

a demodulator coupled to receive a digital baseband output signal from the receiver representative of a tuned transponder channel, the demodulator being configured to tune a program channel within the tuned transponder channel and to provide the tuned program channel as an output;

wherein the LO circuitry comprises phase-lock-loop (PLL) circuitry including a phase detector and a controlled oscillator, the phase detector receiving a first signal representative of a reference frequency, receiving a second signal representative of an output frequency of the controlled oscillator, and generating at least one control signal to adjust the output frequency of the controlled oscillator; and

wherein the LO circuitry further comprises control circuitry configured to receive a channel selection signal and to control divider circuitry that provides the first and second signals to the phase detector based upon divided versions of the reference frequency and the output of the controlled oscillator, the control circuitry acting to select the coarse-tune analog mixing signal output by the PLL circuitry.

13. The satellite set-top box of claim 12, wherein the frequency range of the signal spectrum is organized into a plurality of frequency bins and wherein at least one coarse-tune analog mixing signal is associated with each frequency bin.

14. The satellite set-top box of claim 13, wherein the analog mixing signal selected for output by the LO circuitry is an analog mixing signal associated with the bin within which the desired transponder channel falls.

15. The satellite set-top box of claim 14, wherein a different analog mixing signal is selected by the LO circuitry if the desired transponder channel overlaps the analog mixing signal associated with the bin within which the desired transponder channel falls.

16. The satellite set-top box of claim 13, further comprising configuring the frequency bins not to overlap.

17. The satellite set-top box of claim 13, further comprising configuring the frequency bins such that one or more of the frequency bins overlap in frequency ranges.

18. The satellite set-top box of claim 12, wherein the digital fine tune circuitry comprises a wide-band analog-to-digital converter having the coarsely tuned signal spectrum as an input and having digital signals as an output, and further comprising a tunable digital filter configured to tune the desired channel.

19. The satellite set-top box of claim 12, wherein the digital fine tune circuitry comprises a narrow-band tunable bandpass analog-to-digital converter configured to tune the desired channel and to convert the coarsely tuned signal spectrum to digital signals, and further comprising a tunable digital filter to further tune the desired channel.

20. The satellite set-top box of claim 12, wherein the controlled oscillator utilizes an RC-based resonant structure.