# US 10,320,349 B1 · Multiport amplifier input network with compensation for output network gain and phase frequency response imbalance

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- Number: US 10,320,349 B1
- Document ID: US10320349B1
- Status: Granted
- Kind: B1
- Application number: 15/926,186
- Filed: 2018-03-20
- Published: 2019-06-06
- Granted: 2019-06-11
- Earliest claimed: 2017-12-06
- Assignees: Space Systems/Loral, Inc.
- Applicants: Space Systems/Loral, LLC
- Inventors: Farid Elwailly; James Knecht; David Grybos
- Web page: https://patentgrep.com/patent/US10320349B1

## CPC

- 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)}
- H03F 3/189: High-frequency amplifiers, e.g. radio frequency amplifiers
- H04B 7/18513: {Transmission in a satellite or space-based system}
- H04B 7/2041: {Spot beam multiple access}
- H04B 17/0085: {using test signal generators}
- H04B 17/21: for calibration; for correcting measurements
- H03F 2200/192: A hybrid coupler being used at the input of an amplifier circuit
- Y02D 30/70: in wireless communication networks
- H03F: AMPLIFIERS
- H04B: TRANSMISSION
- Y02D: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE

## Abstract

Beamforming channels of a satellite are calibrated using a low power, spread spectrum calibration signal. The power of the calibration signal is below the noise level of a user signal in an active channel, allowing channels to be calibrated while active. When calibrating the transmit side circuitry, a two-stage calibration can be used, first calibrating the output hybrid matrix, then calibrating the whole of the transmit side. To improve performance, the dwell time spend calibrating a channel can be based on the power of the user signal in the channel. A transmit probe can be used to inject a calibration signal into the receive antennae and a receive probe can be used to extract the calibration signal from the transmit antennae. To reduce frequency of calibrations, the calibrations can be based on path-to-path differences. These techniques are also applied to multiport amplifiers (MPAs).

## Claims

### Claim 1

An amplifier system, comprising:
an input network having a plurality of input ports;
an output network having a plurality of output ports;
a plurality of amplification units coupled between the input network and the output network, the plurality of amplification units configured to amplify signals from the plurality of input ports;
a plurality of equalizers, each coupled between the input network and the output network in series with a corresponding one of the amplification units and configured to equalize signal path of the corresponding amplification unit between the input ports and the output ports; and
one or more calibration circuits configured to generate a calibration signal and inject the calibration signal into a plurality of the paths between the input ports and the output ports before the equalizers concurrently with the amplifier system propagating one or more user signals along the paths between the input ports and the output ports, the calibration signal being a spread spectrum signal with a power level lower than a noise floor of the one or more user signals, the one or more calibration circuits further configured to receive the injected calibration signal from one or more of the output ports after propagation through the amplifier system and perform a comparison of the injected calibration signal to the calibration signal after propagating through the amplifier system.

### Claim 2 (depends on 1)

The amplifier system of claim 1, wherein the input network and the equalizers are part of a digitally implemented virtual input hybrid matrix.

### Claim 3 (depends on 1)

The amplifier system of claim 1, wherein the one or more calibration circuits are coupled to the equalizers and configured to individually adjust signal paths propagating therethrough.

### Claim 4 (depends on 3)

The amplifier system of claim 3, wherein the one or more calibration circuits are configured to adjust a phase of signals propagating through the equalizers.

### Claim 5 (depends on 3)

The amplifier system of claim 3, wherein the one or more calibration circuits are configured to adjust an amplitude of signals propagating through the equalizers.

### Claim 6 (depends on 3)

The amplifier system of claim 3, wherein the one or more calibration circuits are configured to determine parameters to individually adjust signal paths propagating though the equalizers based on the comparison of the injected calibration signal to the calibration signal after propagating through the amplifier system.

### Claim 7 (depends on 6)

The amplifier system of claim 6, wherein the parameters are determined based on path to path differences between the plurality of paths.

### Claim 8 (depends on 3)

The amplifier system of claim 3, wherein the one or more calibration circuits are configured to provide data based on the comparison of the injected calibration signal to the calibration signal after propagating through the amplifier system and to receive parameters to individually adjust signal paths propagating though the equalizers.

### Claim 9 (depends on 1)

The amplifier system of claim 1, wherein the one or more calibration circuits are configured to inject the calibration signal into the plurality of paths after the input network.

### Claim 10 (depends on 1)

The amplifier system of claim 1, wherein the one or more calibration circuits are configured to inject the calibration signal into the plurality of paths before the input network.

### Claim 11 (depends on 10)

The amplifier system of claim 10, wherein the one or more calibration circuits are configured to inject the calibration signal into a plurality of the input ports concurrently.

### Claim 12 (depends on 1)

The amplifier system of claim 1, wherein the one or more calibration circuits are configured to receive the injected calibration signal from a plurality of the output ports concurrently.

### Claim 13

A satellite, comprising:
a plurality of receive antennae;
a plurality of transmit antennae;
a multiport amplifier coupled between the plurality of receive antennae and the plurality of transmit antennae, the multiport amplifier including:
an input hybrid matrix coupled to multiple ones of the receive antennae;
an output hybrid matrix coupled to multiple ones of the transmit antennae;
a plurality of amplification units coupled between the input hybrid matrix and the output hybrid matrix, the plurality of amplification units configured to amplify signals from the input hybrid matrix; and
a plurality of equalizers, each coupled between the input hybrid network and the output hybrid matrix in series with a corresponding one of the amplification units, the equalizers configured to equalize signal paths between the receive antennae and the transmit antennae through the plurality of amplification units; and
one or more calibration circuits connected to the multiport amplifier, the calibration circuits configured to generate and inject a calibration signal into a plurality of signal paths of the multiport amplifier before the equalizers concurrently with the multiport amplifier propagating one or more user signals along the signal paths, the calibration signal being a spread spectrum signal with a power level lower than a noise floor of the one or more user signals, the one or more calibration circuits further configured to receive the injected calibration signal after propagation through the multiport amplifier and perform a comparison of the injected calibration signal to the calibration signal after propagating through the multiport amplifier.

### Claim 14 (depends on 13)

The satellite of claim 13, wherein the input hybrid matrix and the equalizers are part of a digitally implemented virtual input hybrid matrix.

### Claim 15 (depends on 13)

The satellite of claim 13, wherein the one or more calibration circuits are coupled to the equalizers and configured to individually adjust signal paths propagating therethrough.

### Claim 16 (depends on 15)

The satellite of claim 15, further comprising:
a downlink channel whereby the one or more calibration circuits are configured to provide data based on the comparison of the injected calibration signal to the calibration signal after propagating through the multiport amplifier; and
an uplink channel whereby the one or more calibration circuits are configured to receive parameters to individually adjust signal paths propagating though the equalizers.