A CMOS switching power amplifier for ΔΣ digitized polar RF transmitter

A CMOS switching power amplifier for ΔΣ digitized polar RF transmitter is implemented in 0.18-μm process. A current source is introduced in the proposed switching PA to achieve ΔΣ digitized amplitude modulation. The modulation with the current source is suitable for high speed modulated signal such as an oversampled ΔΣ signal. The PA operates at 910 MHz with the maximum output power of 23.5 dBm and power efficiency of 55.4% at the maximum output power. The maximum output power range with the current source modulation is 31 dB.