Communication device with power amplifier crest factor reduction

A transmitter comprising:

• a circuitry to generate at least one multiplexed signal for transmission;
• and
• a power amplifier to amplify the at least one multiplexed signal, the power amplifier comprising:
• a clipper circuit for receiving a baseband signal, the clipper circuit configured to produce a correlated out-of-band noise signal, said clipper circuit further configured to control the adjacent channel leakage ratio (ACLR) of a communication device based on a clipper limiter threshold of the clipper circuit;
• and
• a peak injection circuit coupled to the clipper circuit for receiving said correlated out-of-band noise signal, the peak injection circuit configured to apply an impulse function signal to the correlated out-of-band noise signal, said peak injection circuit further configured to control the error vector magnitude (EVM) of the communication device based on a peak threshold of the peak injection circuit,
• wherein ACLR and EVM are independently controllable.

A method of operating user equipment (UE) comprising:

• producing, via a clipper circuit that receives a baseband signal, a correlated out-of-band noise signal, said clipper circuit configured for controlling the adjacent channel leakage ratio (ACLR) of a communication device, based on a clipper limiter threshold of the clipper circuit;
• and
• Applying, via a peak injection circuit coupled to the clipper circuit for receiving said correlated out-of-band noise signal, an impulse function signal to the correlated out-of-band noise signal, said peak injection circuit further configured to control the error vector magnitude (EVM) of the UE, based on a peak threshold of the peak injection circuit,
• wherein ACLR and EVM are independently controllable.

A crest factor reduction apparatus comprising:

• an out-of-band (OOB) distortions circuit configured to isolate and enhance out-of-band distortions of a first input signal to provide a first complex signal;
• an adder and ratio circuit coupled to the OOB distortions circuit and configured to add the first input signal and the first complex signal, to obtain a desired adjacent channel leakage ratio (ACLR) in a communication device by setting a ratio of power of the first input signal to power of the first complex signal;
• and
• a peak injection circuit coupled to the adder and ratio circuit and configured to receive a second complex signal from the adder and ratio circuit, the peak injection circuit configured to apply a peak function signal to control error vector magnitude (EVM) of the communication device,
• wherein the ACLR and the EVM are independently controllable via a clipped version of the first input signal generated by a clipper circuit configured to have a clipper limiter threshold CL=α·RMS|x|, where x is the first input signal, α defines clipper circuit limiter threshold, and α is related to a cubic metric (CM) of the first input signal,
• wherein the clipped version of the input signal is configured to control the ACLR, and
• wherein the peak injection circuit is configured to generate an impulse function signal, the peak injection circuit configured to have a peak threshold CL=β MAX(|X|) where X is the first input signal, to control the EVM.

A power amplifier comprising:

• a clipper circuit configured to produce a correlated out-of-band noise signal to control adjacent channel leakage ratio (ACLR) of a communication device based on a clipper limiter threshold of the clipper circuit;
• and
• a peak injection circuit coupled to the first circuitry and configured to apply an impulse function signal to the correlated out-of-band noise signal to control error vector magnitude (EVM) of the communication device,
• wherein the clipper circuit is configured to generate a clipping function, and is coupled to a high-pass filter and a multiplier, and
• wherein the clipper circuit is configured to receive a baseband input signal and clip the baseband input signal in accordance with a clip signal of the form CL=α·RMS|x|, where x is the baseband input signal, α defines the clipper limiter threshold of CL, and α is related to a cubic metric (CM) of the baseband input signal.