Quadrature modulator imbalance estimator and modulator stage using it

• US 6,208,698 B1
• Filed: 10/23/1997
• Issued: 03/27/2001
• Est. Priority Date: 10/24/1996
• Status: Expired due to Fees

• Current Assignee: Alcatel SA (Nokia Corporation)
• Original Assignee: Alcatel SA (Nokia Corporation)
• Inventors: Canonici, Jean-Xavier, Marchesani, Rossano
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): Liu, Shuwang
• Application Number:
  US08/956,443
• Time in Patent Office: 1,251 Days
• Field of Search: 375/298, 375/296, 375/200, 375/295, 375/235, 332/103, 381/13
• US Class Current: 375/298
• CPC Class Codes: H04L 27/2071 in which the data are represented by the carrier phase, e.g. systems with differential coding
• CPC Class Codes: H04L 27/364 Arrangements for overcoming imperfections in the modulator, e.g. quadrature error or unbalanced I and Q levels

Abstract

An imbalance estimator for quadrature modulators comprising two mixers to which are applied two carrier signals and to each of which is applied a modulating signal, output signals of said mixers being applied to a combiner to constitute a modulated signal, detects the instantaneous power of the modulated signal. The detected instantaneous power is multiplied by the modulating signals, and the resulting signals are rectified. The rectified signals are rectified to supply signals indicative of the imbalance of the modulator.

Claims

1. An imbalance estimator for a quadrature modulator comprising two mixers, to which are respectively applied two carrier signals, and to which are respectively applied modulating signals, output signals of said mixers being applied to a combiner to constitute a modulated signal, said estimator including:

means for detecting an instantaneous power of said modulated signal;

means for multiplying said detected instantaneous power by said modulating signals, said multiplying means supplying produced signals;

means for rectifying said produced signals; and

means for integrating said rectified produced signals, supplying signals indicative of an amplitude imbalance of said modulator.

3. The estimator claimed in claim 1 wherein said signals supplied by said integrating means are applied to subtractor means supplying a signal indicative of said amplitude imbalance of said modulator.

6. A quadrature modulator adapted to cooperate with an estimator as claimed in claim 1.

8. A quadrature modulator adapted to cooperate with an estimator as claimed in claim 3.

2. An imbalance estimator for a quadrature modulator comprising two mixers, to which are respectively applied two carrier signals, and to which are respectively applied modulating signals, output signals of said mixers being applied to a combiner to constitute a modulated signal, said estimator including:

means for detecting an instantaneous power of said modulated signal;

means for multiplying said detected instantaneous power by absolute values of said modulating signals, said multiplying means supplying rectified produced signals; and

means for integrating said rectified produced signals, thereby supplying signals indicative of an amplitude imbalance of said modulator.

7. A quadrature modulator adapted to cooperate with an estimator as claimed in claim 2.

4. An imbalance estimator for a quadrature modulator comprising two mixers, to which are respectively applied two carrier signals, and to which are respectively applied modulating signals, output signals of said mixers being applied to a combiner to constitute a modulated signal, said estimator including:

means for detecting an instantaneous power of said modulated signal;

means for multiplying said detected instantaneous power by said modulating signals, said multiplying means supplying produced signals;

means for rectifying said produced signals; and

means for integrating a difference between said rectified produced signals, thereby supplying a single signal indicative of an amplitude imbalance of said modulator.

9. A quadrature modulator adapted to cooperate with an estimator as claimed in claim 4.

5. An imbalance estimator for a quadrature modulator comprising two mixers, to which are respectively applied two carrier signals, and to which are respectively applied modulating signals, output signals of said mixers being applied to a combiner to constitute a modulated signal, said estimator including:

means for detecting an instantaneous power of said modulated signal;

means for multiplying said detected instantaneous power by absolute values of said modulating signals, said multiplying means supplying rectified produced signals; and

means for integrating a difference between said rectified produced signals, thereby supplying a single signal indicative of an amplitude imbalance of said modulator.

10. A quadrature modulator adapted to cooperate with an estimator as claimed in claim 5.

11. An imbalance estimator for a quadrature modulator comprising two mixers, to which are respectively applied two carrier signals, and to which are respectively applied modulating signals, output signals of said mixers being applied to a combiner to constitute a modulated signal, said estimator including:

a power detector for detecting an instantaneous power of said modulated signal;

at least one multiplier for multiplying said detected instantaneous power by said modulating signals, said at least one multiplier supplying produced signals;

a rectifier for rectifying said produced signals; and

an integrator for integrating said rectified produced signals, supplying signals indicative of an amplitude imbalance of said modulator.

13. The estimator claimed in claim 11 wherein said signals supplied by said integrator are applied to a subtractor supplying a signal indicative of said amplitude imbalance of said modulator.

16. A quadrature modulator adapted to cooperate with an estimator as claimed in claim 11.

18. A quadrature modulator adapted to cooperate with an estimator as claimed in claim 13.

12. An imbalance estimator for a quadrature modulator comprising two mixers, to which are respectively applied two carrier signals, and to which are respectively applied modulating signals, output signals of said mixers being applied to a combiner to constitute a modulated signal, said estimator including:

a detector detecting an instantaneous power of said modulated signal;

a multiplier multiplying said detected instantaneous power by absolute values of said modulating signals, said multiplier supplying rectified produced signals; and

an integrator integrating said rectified produced signals, thereby supplying signals indicative of an amplitude imbalance of said modulator.

17. A quadrature modulator adapted to cooperate with an estimator as claimed in claim 12.

14. An imbalance estimator for a quadrature modulator comprising two mixers, to which are respectively applied two carrier signals, and to which are respectively applied modulating signals, output signals of said mixers being applied to a combiner to constitute a modulated signal, said estimator including:

a detector detecting an instantaneous power of said modulated signal;

at least two multipliers multiplying said detected instantaneous power by respective ones of said modulating signals, said multipliers supplying produced signals;

at least two rectifiers rectifying said produced signals; and

an integrator integrating a difference between said rectified produced signals, thereby supplying a single signal indicative of an amplitude imbalance of said modulator.

19. A quadrature modulator adapted to cooperate with an estimator as claimed in claim 14.

15. An imbalance estimator for a quadrature modulator comprising two mixers, to which are respectively applied two carrier signals, and to which are respectively applied modulating signals, output signals of said mixers being applied to a combiner to constitute a modulated signal, said estimator including:

a detector detecting an instantaneous power of said modulated signal;

at least two multipliers multiplying said detected instantaneous power by absolute values of respective ones of said modulating signals, said multipliers supplying rectified produced signals; and

an integrator integrating a difference between said rectified produced signals, thereby supplying a single signal indicative of an amplitude imbalance of said modulator.

20. A quadrature modulator adapted to cooperate with an estimator as claimed in claim 15.