Integrated low-IF terrestrial audio broadcast receiver and associated method

• US 20060003729A1
• Filed: 06/30/2004
• Published: 01/05/2006
• Est. Priority Date: 06/30/2004
• Status: Active Grant

• Current Assignee: Skyworks Solutions Incorporated
• Original Assignee: Silicon Laboratories Incorporated
• Inventors: Kasha, Dan B., Tuttle, G. Tyson
• Granted Patent: US 7,272,375 B2
• Time in Patent Office: Days
• US Class Current: 455/333
• CPC Class Codes: H04B 1/18 Input circuits, e.g. for coupling to an antenna or a transmission line coupling networks between antennas or lines and receivers independent of the nature of the receiver H03H
• CPC Class Codes: H04B 1/30 for homodyne or synchrodyne receivers demodulator circuits H03D1/22

Abstract

An integrated low-IF (low intermediate frequency) terrestrial broadcast receiver and associated method are disclosed that provide an advantageous and cost-efficient solution. The integrated receiver includes a mixer, local oscillator generation circuitry, low-IF conversion circuitry, and DSP circuitry. And the integrated receiver is particularly suited for small, portable devices and the reception of terrestrial audio broadcasts, such as FM and AM terrestrial audio broadcast, in such portable devices.

Claims

1. An integrated terrestrial audio broadcast receiver, comprising:

a mixer coupled to receive an RF signal spectrum and a mixing signal as inputs and having a low-IF signal as an output, the RF input signal spectrum comprising a plurality of channels from a terrestrial audio broadcast;

local oscillator (LO) generation circuitry coupled to receive a channel selection signal as an input and configured to provide an oscillation signal, the oscillation signal being dependent upon the channel selection signal and being used to generate the mixing signal for the mixer;

low-IF conversion circuitry coupled to receive the low-IF signal from the mixer and configured to output a digital signal; and

a digital-signal-processor (DSP) coupled to receive the digital signal from the low-IF conversion circuitry and configured to output a digital audio signal;

wherein the mixer, the LO generation circuitry, the low-IF conversion circuitry, and the DSP are integrated within a single integrated circuit.

2. The integrated terrestrial audio broadcast receiver of claim 1, wherein the integrated circuit is made using a process that comprises a CMOS process.

3. The integrated terrestrial audio broadcast receiver of claim 1, wherein the integrated circuit is made using a process that consists essentially of a CMOS process.

4. The integrated terrestrial audio broadcast receiver of claim 1, further comprising a digital-to-analog converter (DAC) coupled to receive the digital audio signal from the DSP and configured to output an analog audio signal.

5. The integrated terrestrial audio broadcast receiver of claim 1, wherein the terrestrial audio broadcast comprises an FM audio signal spectrum comprising a plurality of FM broadcast channels.

6. The integrated terrestrial audio broadcast receiver of claim 1, further comprising input circuitry configured to receive FM audio broadcasts and AM audio broadcasts.

7. The integrated terrestrial audio broadcast receiver of claim 6, further comprising a second mixer configured to receive a mixing signal from the LO generation circuitry, wherein one mixer is coupled to receive FM audio signals and the other mixer is coupled to receive AM audio signals.

8. The integrated terrestrial audio broadcast receiver of claim 1, wherein the LO generation circuitry comprises a voltage controlled oscillator (VCO).

9. The integrated terrestrial audio broadcast receiver of claim 8, wherein the VCO is configured to have output signals at frequencies equal to or above about 2.3 GHz.

10. The integrated terrestrial audio broadcast receiver of claim 8, wherein the VCO comprises LC tank oscillation circuitry and wherein any inductors needed for the LC tank are integrated within the single integrated circuit or included within a package for the single integrated circuit.

11. The integrated terrestrial audio broadcast receiver of claim 8, wherein the LO generation circuitry comprises a frequency locked loop including the VCO.

12. The integrated terrestrial audio broadcast receiver of claim 7, wherein the LO generation circuitry provides output oscillation signals in discrete frequency steps.

13. The integrated terrestrial audio broadcast receiver of claim 1, further comprising quadrature generation circuitry configured to generate two phase shifted mixing signals for use by the mixer.

14. The integrated terrestrial audio broadcast receiver of claim 13, wherein the two phase shifted mixing signals are out of phase by 90 degrees.

15. The integrated terrestrial audio broadcast receiver of claim 13, wherein the two phase shifted mixing signals are out of phase by 120 degrees.

16. The integrated terrestrial audio broadcast receiver of claim 13, wherein the mixer is configured to output real and imaginary signals, and wherein the low-IF conversion circuitry comprises first and second band-pass analog-to-digital converters coupled to the real and imaginary signals and configured to output real and imaginary digital signals.

17. The integrated terrestrial audio broadcast receiver of claim 16, wherein the DSP circuitry includes a channel selection filter configured to provide additional tuning of a desired channel within the RF signal spectrum.

18. The integrated terrestrial audio broadcast receiver of claim 13, wherein the mixer is configured to output real and imaginary signals, and wherein the low-IF conversion circuitry comprises first and second low-pass analog-to-digital converters coupled to the real and imaginary signals and configured to output real and imaginary digital signals.

19. The integrated terrestrial audio broadcast receiver of claim 18, wherein the DSP circuitry includes a channel selection filter configured to provide additional tuning of a desired channel within the RF signal spectrum.

20. The integrated terrestrial audio broadcast receiver of claim 1, further comprising control circuitry coupled to the LO generation circuitry, the control circuitry configured to select an IF target frequency to be utilized by the receiver.

21. The integrated terrestrial audio broadcast receiver of claim 20, wherein the IF target frequency selection is based upon a programmable setting.

22. A portable device having an integrated terrestrial audio broadcast receiver, comprising:

a channel selection interface;

an audio output interface; and

an integrated terrestrial audio receiver coupled to the channel selection interface and the audio output interface, the audio receiver comprising;

a mixer coupled to receive an signal spectrum and a mixing signal as inputs and having a low-IF signal as an output, the signal spectrum comprising a plurality of channels from a terrestrial audio broadcast;

local oscillator (LO) generation circuitry coupled to receive a channel selection signal as an input and configured to provide an oscillation signal, the oscillation signal being dependent upon the channel selection signal and being used to generate the mixing signal for the mixer;

low-IF conversion circuitry coupled to receive the low-IF signal from the mixer and configured to output a digital signal; and

a digital-signal-processor (DSP) coupled to receive the digital signal from the low-IF conversion circuitry and configured to output a digital audio signal.

23. The portable device of claim 22, wherein the portable device has a volume of about 70 cubic inches or less and that has a weight of about 2 pounds or less.

24. The portable device of claim 22, wherein the audio output interface comprises an interface configured to provide a digital audio output signal.

25. The portable device of claim 22, wherein integrated terrestrial audio receiver further comprises digital-to-analog converter (DAC) circuitry coupled to receive the digital audio signal from the DSP and configured to output an analog audio signal, and wherein the audio output interface comprises an interface configured to provide an analog audio output signal.

26. The portable device of claim 22, wherein integrated terrestrial audio receiver further comprises input circuitry configured to receive FM audio signals and AM audio signals.

27. The portable device of claim 22, wherein the integrated circuit is made using a process that consists essentially of a CMOS process.

28. The portable device of claim 22, wherein the integrated circuit is configured to draw about 30 mA of current or less during operation.

29. The portable device of claim 28, wherein the integrated circuit within the portable device requires about six or fewer external components.

30. A method for tuning terrestrial audio broadcasts in an integrated receiver, comprising:

generating an oscillation signal, the oscillation signal being dependent upon a channel selection signal;

creating a mixing signal based upon the oscillation signal;

mixing an RP input signal spectrum having a plurality of channels from a terrestrial audio broadcast with the mixing signal to generate a low-IF output signal;

converting the low-IF output signal to a digital signal; and

processing the digital signal to generate a digital audio signal;

wherein the generating, creating, mixing, converting and processing steps are performed within a single integrated circuit.

31. The method of claim 30, wherein the integrated circuit is made using a process that comprises a CMOS process.

32. The method of claim 30, wherein the integrated circuit is made using a process that consists essentially of a CMOS process.

33. The method of claim 30, further comprising converting the digital audio signal to an analog audio signal within the single integrated circuit.

34. The method of claim 30, wherein the RF input signal spectrum comprises an FM audio signal spectrum comprising a plurality of FM broadcast channels.

35. The method of claim 30, further comprising providing input circuitry configured to receive FM audio signals and AM audio signals.

36. The method of claim 30, wherein the processing step comprises FM demodulation and stereo decoding.

37. The method of claim 30, further comprising generating two phase shifted mixing signals for use in the mixing step.

38. The method of claim 30, wherein the converting step comprises utilizing a band-pass analog-to-digital converter (ADC) circuit to convert the real low-IF signal to a digital signal and utilizing a band-pass analog-to-digital converter (ADC) circuit to convert the imaginary low-IF signal to a digital signal.

39. The method of claim 30, wherein the converting step comprises utilizing a low-pass analog-to-digital converter (ADC) circuit to convert the real low-IF signal to a digital signal and utilizing a low-pass analog-to-digital converter (ADC) circuit to convert the imaginary low-If signal to a digital signal.

40. The method of claim 30, further comprising selecting an IF target frequency to be utilized by the receiver based upon a programmable setting.