Simplified high frequency tuner and tuning method

• US 7,639,996 B2
• Filed: 07/10/2008
• Issued: 12/29/2009
• 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:
  US12/171,036
• Publication Number:
  US 20080318536A1
• Time in Patent Office: 537 Days
• Field of Search: 455/142, 455/143, 455/324, 375/322
• US Class Current: 455/150.1
• 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 tuning method comprising, with a tuning device:

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

(b) frequency translating the channel of interest to a passband that is near-baseband and the lower edge of which is spaced from DC by at least about the channel spacing, by mixing the channel of interest with approximately phase-quadrature local oscillator signals, thereby creating I and Q signals;

(c) sensing the operating temperature of the tuning device; and

(d) using the sensed temperature to correct errors between the I and Q signals.

2. The method of claim 1 wherein correcting errors comprises choosing a correction factor to optimize image rejection.

3. The method of claim 1 wherein the passband bandwidth is about the channel spacing.

4. A tuning method comprising:

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

(b) frequency translating the channel of interest to a passband that is near baseband and the lower edge of which is spaced from DC by at least about the channel spacing, by mixing the channel of interest with approximately phase-quadrature local oscillator signals, thereby creating I and Q signals; and

(c) using information characterizing errors between the I and Q channels of the individual tuning device, which information has been stored within the device upon completion of device manufacture, to correct errors between the I and Q channels.

5. The method of claim 4 wherein the passband bandwidth is about a channel spacing wide.

6. The method of claim 4 wherein the information characterizing errors constitutes correction factors.

7. A method of tuning comprising:

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

(b) frequency translating the channel of interest to a passband that is near-baseband and the lower edge of which is spaced from DC by at least about the channel spacing, by mixing the channel of interest with approximately phase-quadrature local oscillator signals thereby creating I and Q signals; and

(c) continuously detecting and correcting errors between the I and Q channels.

8. The method of claim 7 wherein the passband bandwidth is about the channel spacing wide.

9. An apparatus for tuning a channel of interest from a channelized spectrum having a predetermined channel spacing, the apparatus comprising:

(a) a local oscillator configured to generate approximately phase-quadrature local oscillator signals;

(b) a filter configured to define a near-baseband passband;

(c) mixers, each responsive to one of the phase-quadrature local oscillator signals and the signal of interest, that frequency-translate the signal of interest creating I and Q signals that fall within the near-baseband passband; and

(d) an operating-temperature sensor coupled to correct errors between the I and Q signals.

10. The apparatus of claim 9 wherein the near-baseband passband is frequency-spaced from DC by at least about the channel spacing.

11. The apparatus of claim 9 wherein the bandwidth of the near-baseband passband is about a channel spacing.

12. The apparatus of claim 9 wherein the operating-temperature sensor is coupled to generate a correction factor selected to optimize unwanted signal rejection.

13. The apparatus of claim 9 wherein the sensor is coupled to correct errors between the I and Q signals through a digital controller.

14. A method of tuning comprising:

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

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

(c) frequency translating the channel of interest to a near-baseband passband that has a width equal to about the channel spacing plus a fine tuning adjustment;

(d) fine tuning the channel of interest by passing a selected range of passband;

(e) sensing the operating temperature of the tuning device; and

(f) using the sensed temperature to correct errors between the I and Q channels.

15. The method of claim 14 wherein correcting errors comprises choosing one or more correction factors to optimize image rejection.

16. The method of claim 14 wherein the passband is spaced from DC by at least about the channel spacing.

17. The method of claim 14 wherein fine tuning of the channel of interest is done by digitally controlled variable passband filtering.

18. A tuning method comprising, with a tuning device:

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

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

(c) frequency translating the channel of interest to a near-baseband passband that has a width equal to about the channel spacing;

(d) dynamically varying the passband bandwidth;

(e) further translating the frequency-translated channel of interest to baseband by mixing the frequency-translated channel of interest with a second local oscillator signal; and

(f) sensing the operating temperature of the tuning device and using the sensed temperature information to correct errors between the I and Q channels.

19. The method of claim 18 wherein the lower edge of the passband is spaced from DC by at least about the channel spacing.

20. The method of claim 18 wherein the passband is varied to follow variations in the channel of interest.

21. The method of claim 18 wherein the second local oscillator signal has a frequency that is approximately the center frequency of the frequency-translated channel of interest.

22. The method of claim 21 further comprising fine-turning the translation to baseband of the frequency-translated channel of interest by adjusting the second local oscillator frequency.

23. The method of claim 22 wherein the frequency translation to baseband is done in the digital domain.