A monolithic SiGe BiCMOS envelope-tracking power amplifier (PA) is demonstrated for 802.1 lg OFDM applications at 2.4 GHz. The 4-mm2 die includes a high-efficiency high-precision envelope amplifier and a two-stage SiGe HBT PA for RF amplification. Off-chip digital predistortion is employed to improve EVM performance. The two-stage amplifier exhibits 12-dB gain, <5% EVM, 20-dBm OFDM output power, and an overall efficiency (including the envelope amplifier) of 28%.
- Envelope tracking
- Orthogonal frequency-division multiplexing (OFDM)
- Power amplifier (PA)
- Wireless localarea network (WLAN)