Linearization circuits and methods for power amplification
Linearization circuits of the invention are used in conjunction with power amplification circuits that comprise a power amplifier core. Exemplary linearization circuits comprise a replica of the power amplifier core. In operation, the linearization produces an envelope signal from an RF signal. The envelope signal is used to control the replica to produce an analog output signal which represents the inverse of the AM to AM distortion of the power amplifier core. The linearization circuit then biases the RF signal with the inverted non-linear signal of the replica to control the power amplifier core. The power amplifier core and the replica thereof can be defined on the same semiconductor die so both respond to process variables similarly.
1. A method for amplifying an RF signal, the method comprising:
producing an envelope signal from the RF signal;
producing, on a die, an inverted non-linear signal from the envelope signal; and
producing a linearly amplified RF signal by applying a biased RF signal to a MOS transistor of a power amplifier core on the die, where the biased RF signal comprises the RF signal plus the inverted non-linear signal.
2. The method of claim 1 wherein producing the inverted non-linear signal includes controlling, with the envelope signal, a gate of a transistor of a replica of the power amplifier core.
3. The method of claim 1 wherein the biased RF signal additionally comprises a DC bias voltage.
4. The method of claim 1 wherein producing the envelope signal from the RF signal is also performed on the die.
5. The method of claim 1 wherein a clock signal is not employed.
6. The method of claim 1 wherein analog to digital conversion is not performed.