In-phase and quadrature-phase rebalancer

• US 20020097812A1
• Filed: 12/01/2000
• Published: 07/25/2002
• Est. Priority Date: 12/01/2000
• Status: Abandoned Application

• Current Assignee: John Wiss
• Original Assignee: John Wiss
• Inventors: Wiss, John
• Application Number:
  US09/727,993
• Publication Number:
  US 20020097812A1
• Time in Patent Office: Days
• US Class Current: 375/316
• CPC Class Codes: H03D 3/009 Compensating quadrature phase or amplitude imbalances
• CPC Class Codes: H04L 2027/0016 Stabilisation of local oscillators
• CPC Class Codes: H04L 2027/0081 between loops of different bandwidths
• CPC Class Codes: H04L 2027/0085 with no special signals for synchronisation
• CPC Class Codes: H04L 27/3411 reducing the peak to average power ratio or the mean power of the constellation; Arrangements for increasing the shape gain of a signal set
• CPC Class Codes: H04L 27/3433 using an underlying square constellation
• CPC Class Codes: H04L 27/3438 using an underlying generalised cross constellation
• CPC Class Codes: H04L 27/3863 Compensation for quadrature error in the received signal

Abstract

A first variable gain function is in series with an unbalanced in-phase component, and a circuit loop produces a first error signal which varies the first gain function such that its output is a signal which continuously converges toward a balanced in-phase component. A second variable gain function receives as input the unbalanced in-phase component, and a summing function in series with the unbalanced quadrature component algebraically adds the unbalanced quadrature component and the output of the second gain function. A second circuit loop produces a second error signal which varies the second gain function such that the output of the summing function is a signal which continuously converges toward a balanced quadrature component. Preferably the first error signal is produced by respectively squaring the outputs of the first gain function and the summing function, finding the difference of the squares, multiplying the difference of the squares by a selected convergence parameter, and continuously integrating the multiplied difference. Preferably the second error signal is produced by multiplying the outputs of the first gain function and the summing function, multiplying the product of the first gain function and the summing function by a selected convergence parameter, and continuously integrating the output of the multiplier. Also preferably the error signal loops are each normalized. Optionally, an initial set of convergence parameters can be applied to speed-up the start of convergence, and a second set of smaller values can be applied some time later for more precise convergence.

Claims

1. A continuously adaptive device for rebalancing quantized in-phase and quadrature phase components of a received signal comprising:

(a) a first variable gain function in series with the unbalanced in-phase component;

(b) means for varying the first gain function such that its output is a signal which continuously converges toward a balanced in-phase component;

(c) a second variable gain function which receives as input the unbalanced in-phase component;

(d) a summing function in series with the unbalanced quadrature component which algebraically adds the unbalanced quadrature component and the output of the second gain function; and

(e) means for varying the gain of the second gain function such that the output of the summing function is a signal which continuously converges toward a balanced quadrature component.

2. The device according to claim 1 wherein:

(a) the first gain function varies according to a first error signal, the first error signal being produced by a loop comprising;

(1) means for respectively squaring the outputs of the first gain function and the summing function,

(2) means for finding the difference of the squares,

(3) means for multiplying the difference of the squares by a selected convergence parameter, and

(4) means for continuously integrating the multiplied difference; and

(b) the second gain function varies according to a second error signal, the second error signal being produced by a loop comprising;

(1) means for multiplying the outputs of the first gain function and the summing function,

(2) a multiplier for multiplying the product of the first gain function and the summing function by a selected convergence parameter, and

(3) means for continuously integrating the output of the multiplier.

3. The device according to claim 2 wherein the difference of the squares, and the product of the outputs of the first gain function and the summing function are each normalized.

4. The device according to claim 2 wherein the two convergence parameters have different values.

5. The device according to claim 2 further comprising a first set of selected convergence parameters which are applied initially to speed-up convergence, and a second set of convergence parameters which are applied some time later for more precise convergence.

6. A method of adaptively rebalancing quantized in-phase and quadrature phase components of a received signal comprising the steps:

(a) multiplying the unbalanced in-phase component with a first variable coefficient to produce a first product;

(b) varying the first coefficient such that the first product is a signal which continuously converges toward a balanced in-phase component;

(c) multiplying the unbalanced in-phase component with a second variable coefficient to produce a second product;

(d) summing the unbalanced quadrature component and the second product to produce a first sum; and

(e) varying the second coefficient such that the first sum is a signal which continuously converges toward a balanced quadrature component.

7. The method according to claim 6 wherein:

(a) the step of varying the first coefficient comprises the steps;

(1) respectively squaring the first product and the first sum;

(2) finding the difference of the two squares;

(3) multiplying the difference of the two squares by a selected convergence parameter, and

(4) continuously integrating of the multiplied difference; and

(b) the step of varying the second coefficient comprises the steps;

(1) multiplying the first product and the first sum to produce a second product,

(2) multiplying the second product by a selected convergence parameter, and

(3) continuously integrating of the multiplied second product.

8. The method according to claim 7 further comprising the steps:

(a) applying a first set of selected convergence parameters initially to speed-up convergence, and

(b) applying a second set of convergence parameters some time later for more precise convergence.