Simplified high frequency tuner and tuning method

• US 8,903,347 B2
• Filed: 05/23/2013
• Issued: 12/02/2014
• Est. Priority Date: 09/13/1996
• Status: Expired due to Fees

• Current Assignee: University of Washington
• Original Assignee: University of Washington
• Inventors: Suominen, Edwin A.
• Primary Examiner(s): Jackson, Blane J
• Application Number:
  US13/901,355
• Publication Number:
  US 20130251073A1
• Time in Patent Office: 558 Days
• Field of Search: 455/255, 455/256, 455/257, 455/258, 455/260, 455/266, 455/296, 455/302
• US Class Current: 455/302
• CPC Class Codes: H03D 3/007 by converting the oscillations into two quadrature related signals H03D3/245 takes precedence
• CPC Class Codes: H03D 3/009 Compensating quadrature phase or amplitude imbalances
• CPC Class Codes: H03D 7/165 at least two frequency changers being located in different paths, e.g. in two paths with carriers in quadrature combined with amplitude demodulation H03D1/2245, combined with angle demodulation H03D3/007; N-path filters H03H19/002
• CPC Class Codes: H04B 1/06 Receivers
• CPC Class Codes: H04B 1/10 Means associated with receiver for limiting or suppressing noise or interference
• CPC Class Codes: H04B 1/16 Circuits
• CPC Class Codes: H04B 1/26 for superheterodyne receivers multiple frequency-changing H03D7/16
• CPC Class Codes: H04B 1/30 for homodyne or synchrodyne receivers demodulator circuits H03D1/22
• CPC Class Codes: H04L 25/067 providing soft decisions, i.e. decisions together with an estimate of reliability H04L25/068 and H04L25/069 take precedence; sequence estimation techniques H04L25/03178

Abstract

A disclosed method tunes a signal from a channelized spectrum having a predetermined channel spacing. A signal of interest having a predetermined maximum bandwidth is mixed with a local oscillator signal, which has a frequency that is an integer multiple of the channel spacing or one-half of a channel spacing displaced from an integer multiple of the channel spacing. The local oscillator signal is selected to frequency translate the signal of interest to within a near-baseband passband whose lower edge is spaced from DC by at least about the maximum bandwidth of the signal of interest. Problems associated with 1/f noise, DC offsets, and self-mixing products are avoided or substantially diminished. Other methods and systems are also disclosed.

Claims

1. A method for dynamically selecting high-side or low-side injection of local oscillator mixing signals to help reject images within a receiver, comprising:

(a) providing a mixer configured to utilize a mixing signal to mix an input signal to a desired frequency;

(b) receiving an RF signal spectrum including a plurality of channels;

(c) identifying a channel within the RF signal spectrum to be tuned;

(d) selecting high-side injection or low-side injection for the mixing signal;

(e) generating a high-side local oscillation (LO) signal if high-side injection is selected, and generating a low-side local oscillation (LO) signal if low-side injection is selected;

(f) and mixing the RF signal spectrum with the local oscillation signal that was selected and generated so as to mix the channel to be tuned down to the desired frequency;

(g) low-IF conversion circuitry coupled to receive the low-IF signals from the mixer and configured to output digital signals, the low-IF conversion circuitry including first and second analog-to-digital converters coupled to the real and imaginary low-IF signals and configured to output real and imaginary digital signals; and

,

(h) a digital-signal-processor (DSP) coupled to receive the digital signal from the low-IF conversion circuitry and configured to demodulate the signal within the selected radio channel, to digitally tune the selected radio channel, and to output a digital signal, the DSP comprising an on-chip, general purpose, digital processor.

2. The method of claim 1 wherein the receiving, identifying, selecting, generating and mixing steps are performed within a single integrated circuit.

3. The method of claim 1 further comprising generating two phase shifted mixing signals for use by the mixer, the mixer operating to generate I and Q output signals.

4. The method of claim 1 wherein the desired frequency is a low-IF frequency.

5. The method of claim 4 wherein the receiving, identifying, selecting, generating and mixing steps are performed within a single integrated circuit.

6. The method of claim 1 wherein the RF signal spectrum comprises an RF terrestrial audio broadcast spectrum.

7. An integrated receiver, comprising:

(a) a mixer coupled to receive an RF signal spectrum and a mixing signal as inputs and having a mixed signal as an output,

(b) the RF signal spectrum comprising a plurality of channels;

(c) local oscillator (LO) generation circuitry configured to provide an oscillation signal as an output,

(d) the oscillation signal being used to generate the mixing signal for the mixer;

(e) conversion circuitry coupled to receive the mixed signal from the mixer and configured to output a digital signal;

(f) digital-signal-processor (DSP) circuitry coupled to receive the digital signal from the conversion circuitry and configured to output a tuned digital signal,

(g) the DSP circuitry including tuning control coupled to the DSP and to the LO generation circuitry,

(h) the tuning control being configured to select high-side or low-side injection of one or more frequencies within the RF signal spectrum, and

(i) to control the LO generation circuitry to provide a high-side LO signal or a low-side LO signal depending upon the injection selection.

8. The integrated receiver of claim 7 further comprising quadrature generation circuitry configured to generate two phase shifted mixing signals for use by the mixer, the mixer operative to generate I and Q output signals.

9. The integrated receiver of claim 7 wherein the mixed signal is at low-IF frequency.

10. The integrated receiver of claim 7 wherein the RF signal spectrum comprises an RF terrestrial audio broadcast spectrum.