# US 2014/0155128 A1 · Unequal Amplifier Gain Compression Via Shaping Table

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- Number: US 2014/0155128 A1
- Document ID: US20140155128A1
- Status: Published application
- Kind: A1
- Application number: 13/922,924
- Filed: 2013-06-20
- Published: 2014-06-05
- Earliest claimed: 2012-12-03
- Assignees: Broadcom Corporation
- Applicants: Broadcom Corporation
- Inventors: Sriraman Dakshinamurthy; Bongseok Park; Ying Xia; Robert Gustav Lorenz
- Web page: https://patentgrep.com/patent/US20140155128A1

## CPC

- H04W 52/0209: {in terminal devices}
- Y02D 30/70: in wireless communication networks
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)
- 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

A communication device, such as a smart phone, includes an envelope tracking power supply that provides a voltage supply signal for a power amplifier. The envelope tracking signal input to the envelope tracking power supply arises from application of a shaping table on a desired transmit signal. The shaping table implements non-uniform gain compression across a range of output powers, and in particular may aggressively compress the power amplifier for low output powers, and less aggressively compress the power amplifier at high output powers. The non-uniform gain implemented via the shaping table may provide significant power savings, while still allowing the transmitter to meet spectral mask requirements.

## Claims

### Claim 1

A system comprising:
a shaping table operable to produce, from an input signal, an envelope tracking signal characterized by a signal envelope;
an envelope tracking power supply operable to:
receive the envelope tracking signal; and
produce a voltage supply signal for an amplifier that approximates the signal envelope; and
a controller operable to:
establish an input/output relationship for the shaping table that is operable to cause unequal gain compression for the amplifier across a range of transmit signal amplitudes of a transmit signal.

### Claim 2 (depends on 1)

The system of claim 1, where the unequal gain compression comprises:
lower gain compression for the amplifier for selected higher transmit signal amplitudes in the range, compared to lower transmit signal amplitudes in the range.

### Claim 3 (depends on 1)

The system of claim 1, where the unequal gain compression comprises:
higher gain compression for the amplifier for lower transmit signal amplitudes in the range, compared to greater transmit signal amplitudes in the range.

### Claim 4 (depends on 3)

The system of claim 3, further comprising:
signal adaptation logic operable to provide a boost to the transmit signal at the lower transmit signal amplitudes.

### Claim 5 (depends on 4)

The system of claim 4, where the signal adaptation logic comprises digital pre-distortion logic.

### Claim 6 (depends on 4)

The system of claim 4, where the boost is operable to compensate for the higher gain compression.

### Claim 7 (depends on 4)

The system of claim 4, where the boost is operable to linearize the unequal gain compression.

### Claim 8 (depends on 1)

The system of claim 1, further comprising:
signal adaptation logic operable provide a variable boost to the input signal that decreases moving from lower transmit signal amplitudes to higher transmit signal amplitudes.

### Claim 9 (depends on 8)

The system of claim 8, further comprising:
a power amplifier driver prior to the amplifier that is operable to provide a radio frequency drive signal to the power amplifier that includes the variable boost.

### Claim 10

A system comprising:
a shaping table operable to convert an input signal into an envelope tracking power supply reference signal; and
a controller operable to implement an input/output relationship in the shaping table such that the envelope tracking power supply reference signal causes unequal gain compression across a specified range of transmit signal amplitudes.

### Claim 11 (depends on 10)

The system of claim 10, further comprising:
a preamplifier in communication with the controller and operable to compensate for the unequal gain compression.

### Claim 12 (depends on 10)

The system of claim 10, further comprising:
a preamplifier in communication with the controller and operable to compensate for the unequal gain compression by driving a transmit amplifier harder where the unequal gain compression is greater.

### Claim 13 (depends on 10)

The system of claim 10, further comprising:
signal adaptation logic operable to digitally boost to the input signal to compensate for the unequal gain compression.

### Claim 14 (depends on 10)

The system of claim 10, further comprising:
signal adaptation logic operable to digitally boost the input signal to linearize the unequal gain compression.

### Claim 15 (depends on 10)

The system of claim 10, where the unequal gain compression comprises:
decreasing gain compression from lower transmit signal amplitudes in the range to higher transmit signal amplitudes in the range.

### Claim 16 (depends on 15)

The system of claim 15, further comprising:
signal adaptation logic operable to digitally boost to the input signal to compensate for the decreasing gain compression from lower to higher transmit signal amplitudes.

### Claim 17 (depends on 15)

The system of claim 15, further comprising:
a radio frequency driver for an amplifier, the radio frequency driver in communication with the controller and operable to compensate for the unequal gain compression by driving the amplifier harder as the gain compression increases.

### Claim 18

A system comprising:
a baseband controller operable to:
determine an input/output relationship that causes unequal gain compression across a specified range of transmit signal amplitudes; and
prepare a transmit signal for transmission;
a shaping table in communication with the baseband controller, the shaping table operable to:
implement the input/output relationship; and
produce, from the transmit signal, an envelope tracking signal characterized by a signal envelope according to the input/output relationship;
an envelope tracking power supply operable to:
receive the envelope tracking signal; and
output a power supply voltage signal that approximates the signal envelope;
a power amplifier operable to receive the power supply voltage signal and drive a transmit antenna;
a radio frequency (RF) driver between the baseband controller and the power amplifier, the RF driver operable to:
receive a gain compensated version of the transmit signal from the baseband controller; and
drive the power amplifier with a driving signal generated from the gain compensated version of the transmit signal.

### Claim 19 (depends on 18)

The system of claim 18, where the unequal gain compression comprises non-linear increasing gain compression as transmit signal amplitudes in the range decrease.

### Claim 20 (depends on 19)

The system of claim 19, further comprising:
signal adaption logic operable to generate the gain compensated version of the transmit signal so that the gain compensated version of the input signal results in linearization of the non-linear gain compression for transmissions through the transmit antenna.