METHOD OF CALIBRATING A MULTIPORT AMPLIFIER, MULTIPORT AMPLIFIER ALLOWING THE IMPLEMENTATION OF SUCH A METHOD, AND SATELLITE COMPRISING SUCH AN AMPLIFIER

• US 20140354355A1
• Filed: 05/02/2014
• Published: 12/04/2014
• Est. Priority Date: 05/03/2013
• Status: Active Grant

• Current Assignee: Thales SA
• Original Assignee: Thales SA
• Inventors: MOREAU, Pierre-Henry
• Granted Patent: US 9,413,306 B2
• Time in Patent Office: Days
• US Class Current: 330/124.R
• CPC Class Codes: H03F 2200/429 Two or more amplifiers or one amplifier with filters for different frequency bands are coupled in parallel at the input or output
• CPC Class Codes: H03F 2200/451 the amplifier being a radio frequency amplifier
• CPC Class Codes: H03F 3/189 High-frequency amplifiers, e.g. radio frequency amplifiers
• CPC Class Codes: H03F 3/20 Power amplifiers, e.g. Class B amplifiers, Class C amplifiers H03F3/26 - H03F3/30 take precedence
• CPC Class Codes: H03F 3/211 using a combination of several amplifiers H03F3/60 takes precedence
• CPC Class Codes: H03F 3/602 Combinations of several amplifiers
• CPC Class Codes: H03F 3/68 Combinations of amplifiers, e.g. multi-channel amplifiers for stereophonics power amplifiers using a combination of several semiconductor amplifiers H03F3/211; combinations of amplifiers using coupling networks with distributed constants H03F3/602

Abstract

A method of calibrating a multiport amplifier comprising a plurality of input ports, a plurality of power amplifiers linked to input ports by a matrix distributing signals, a plurality of output ports linked to the power amplifiers by a matrix recombining signals and a plurality of elements for weighting the signals associated with the power amplifiers, comprises: determining a normalized mean cross-correlation between an output signal present at the output port, taken as reference, and the signals present at the other output ports; and iteratively adjusting weights of the weighting elements so as to minimize the normalized mean cross-correlation or to render it less than a predetermined threshold. A multiport amplifier comprising a calibration module configured or programmed to implement such a calibration method, and a satellite for telecommunications whose payload comprises such a multiport amplifier, are also provided.

Claims

1. A method of calibrating a multiport amplifier comprising a plurality of input ports, a plurality of power amplifiers linked to said input ports by way of a matrix for distributing signals and a plurality of output ports linked to said power amplifiers by way of a matrix for recombining signals, said matrices for distributing and recombining signals being adapted for dividing a signal present at a said input port between a plurality of said power amplifiers and for recombining said signal, amplified, at the level of a said output port, an element for weighting the signals being associated with each said power amplifier;

wherein said method comprises the steps of;

a) determining a normalized mean cross-correlation between an output signal present at a said output port, taken as reference, and the signals present at the other said output ports; and

b) iteratively adjusting weights of said weighting elements so as to minimize said normalized mean cross-correlation or to render it less than a predetermined threshold.

2. The method according to claim 1, wherein said normalized mean cross-correlation is normalized with respect to a mean auto-correlation of the signal present at said output port taken as reference.

3. The method according to claim 1, wherein the output port taken as reference is that which exhibits the signal having the highest power level.

4. The method according to claim 1, wherein said weights are complex weights, each comprising a modulus and a phase, said step b) comprising the sub-steps of:

b1) iteratively adjusting the phases of said weights; and

b2) iteratively adjusting the moduli of said weights.

5. The method according to claim 4, wherein said sub-steps b1) and b2) are implemented successively, in an arbitrary order, and in which:

said sub-step b1) comprises the successive adjusting of the phases of the weights of the weighting elements associated with the various power amplifiers; and

said sub-step b2) comprises the successive adjusting of the moduli of the weights of the weighting elements associated with the various power amplifiers.

6. The method according to claim 1, in which said step b) comprises the following operations:

i. determining said normalized mean cross-correlation;

ii. applying a predefined increment to a modulus and/or to a phase of a said weight to be adjusted;

iii. re-determining said normalized mean cross-correlation and, if its value has increased, changing the sign of said increment; and

iv. applying said predefined increment to said phase and/or to said modulus of said weight to be adjusted, with the sign determined during operation iii;

v. re-determining said normalized mean cross-correlation and, if its value has decreased while remaining greater than a predefined threshold, repeating operations iv. and v.

7. The method according to claim 1, wherein said normalized mean correlations are determined inside a frequency band substantially coincident with that of the signal present on said reference port.

8. The method according to claim 1, wherein the signals present on said output ports exhibit a disjoint frequency plan.

9. The method according to claim 1, wherein no measurement signal is injected into said amplifier in order to carry out the calibration.

10. A multiport amplifier comprising a plurality of input ports, a plurality of power amplifiers linked to said input ports by way of a matrix for distributing signals and a plurality of output ports linked to said power amplifiers by way of a matrix for recombining signals, said matrices for distributing and recombining signals being adapted for dividing a signal present at a said input port between a plurality of said power amplifiers and for recombining said signal, amplified, at the level of a said output port, an element for weighting the signals being associated with each said power amplifier;

further comprising a calibration module configured or programmed to implement a calibration method according to claim 1.

11. The multiport amplifier according to claim 10, wherein said calibration module comprises:

a first and a second selector for selecting a first and a second output port;

a first and a second (acquisition chain for acquiring the signals present on said first and second output ports, for selecting, converting to an intermediate frequency, filtering and digitizing said signals; and

a processor programmed or configured to;

drive said first and second selectors and said first and second acquisition chains;

acquire the digitized signals arising from said acquisition chains;

on the basis of the digitized signals acquired, calculate a normalized mean cross-correlation between an output signal acquired from an output port, taken as reference, and the signals acquired from the other output ports;

iteratively adjust the weights of said weighting elements so as to minimize said normalized mean cross-correlation or to render it less than a predetermined threshold.

12. The multiport amplifier according to claim 11, wherein said processor is remotely sited in whole or in part.

13. The multiport amplifier according to claim 10, wherein each said weighting element comprises a variable attenuator and a variable phase shifter connected in cascade.

14. The multiport amplifier according to claim 10, operating in at least one band chosen from among the Ku band, the K band and the Ka band.

15. A satellite for telecommunications whose payload comprises a multiport amplifier according to claim 10.