Simplified high frequency tuner and tuning method

• US 8,116,705 B2
• Filed: 11/09/2009
• Issued: 02/14/2012
• Est. Priority Date: 09/13/1996
• Status: Expired due to Fees

• Current Assignee: Washington Research Foundation (University of Washington)
• Original Assignee: University of Washington
• Inventors: Suominen, Edwin A.
• Primary Examiner(s): Bhattacharya, Sam
• Application Number:
  US12/614,623
• Publication Number:
  US 20100056086A1
• Time in Patent Office: 827 Days
• Field of Search: 455/142, 455/143, 455/324, 375/322
• US Class Current: 455/142
• 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 tuning a signal of interest from within a channelized spectrum, the method comprising:

(a) splitting an incoming signal into two signal paths;

(b) generating an approximately quadrature local oscillator signal from a local oscillator that is coarse-tunable across the channelized spectrum with a step size that is an integer multiple of the channel spacing;

(c) quadrature mixing the split incoming signal with the local oscillator signal, thereby;

(1) frequency translating to a near-baseband passband an upper high frequency spectrum of interest from above the frequency of the local oscillator signal and a lower high frequency spectrum of interest from below the frequency of the local oscillator signal, the near-baseband passband being defined with reference to a lower frequency F1 and an upper frequency F2, wherein F1=F2−

F1 and F1 is at least about the maximum bandwidth of the signal of interest; and

(2) producing I and Q signals in approximate quadrature relation;

(d) limiting the frequency spectrum of the I and Q signals, wherein spectrum coverage is provided of a selected one of the high frequency spectra of interest and analog processing of signals at or close to DC is avoided; and

(e) repeating (a) through (d) in turn for a plurality of local oscillator frequencies, wherein high frequency spectra of interest tunable with the local oscillator frequencies of the plurality are interspersed among local oscillator frequencies of the plurality within the channelized spectrum.

2. The method of claim 1 wherein limiting the frequency spectrum of the I and Q signals comprises filtering the signals in continuous-time using switched-capacitor circuitry.

3. The method of claim 1 wherein limiting the frequency spectrum of the I and Q signals comprises highpass and lowpass filtering the signals in continuous-time.

4. The method of claim 3 wherein limiting the frequency spectrum of the I and Q signals further comprises filtering the signals in discrete-time.

5. The method of claim 1 further comprising:

(a) converting the I and Q signals to digital I and Q signals; and

(b) combining the digital I and Q signals to reject an undesired mixing image.

6. The method of claim 5 further comprising correcting amplitude and phase errors between the digital I and Q signals.

7. A method of tuning a signal of interest from a channelized spectrum, comprising:

(a) receiving a signal of interest from a channelized spectrum having a predetermined channel spacing;

(b) mixing the signal of interest with approximately phase-quadrature local oscillator signals, thereby creating I and Q signals; and

(c) frequency translating the signal of interest to a near-baseband passband that is spaced from DC by about the passband width;

(d) wherein the local oscillator signals have a frequency that is selected to dynamically track frequency movement of the signal of interest;

(e) the signal of interest lies within one of an upper high frequency spectrum of interest and a lower high frequency spectrum of interest; and

(f) the method further comprises providing spectrum coverage within one of the high frequency spectra of interest and not the other.

8. The method of claim 7 wherein the lower edge of the near-baseband passband is spaced from DC by at least about a channel spacing of the channelized spectrum.

9. The method of claim 8 wherein the frequency of the local oscillator signals is one-half of a channel spacing displaced from an integer multiple of the channel spacing.

10. The method of claim 8 wherein the lower edge of the near-baseband passband is spaced from DC by about a channel spacing and the near-baseband passband has a width equal to about the channel spacing.

11. The method of claim 7 wherein the lower edge of the near-baseband passband is spaced from DC by at least about the maximum bandwidth of the signal of interest.

12. The method of claim 11 wherein the lower edge of the near-baseband passband is spaced from DC by about the maximum bandwidth of the signal of interest and the near-baseband passband has a width equal to about the maximum bandwidth of the signal of interest.

13. A method of tuning a signal of interest having a predetermined bandwidth, comprising:

(a) splitting an incoming signal into two signal paths;

(b) generating an approximately quadrature local oscillator signal;

(c) quadrature mixing the split incoming signal with the local oscillator signal, thereby frequency translating the signal of interest to within a near-baseband passband that (1) is spaced from DC by at least about the maximum bandwidth of the signal of interest, and (2) is about as wide as said maximum bandwidth; and

(e) filtering the frequency translated signal of interest with a bandpass filter having a variable passband.