A 90nm CMOS power amplifier for 802.16e (WiMAX) applications

We demonstrate a single stage 90 nm CMOS power amplifier for 2.3-2.7 GHz WiMAX (802.16e) band applications. An integrated BALUN is used to match the output to 50 ohm load. The PA gain and saturated power are +18 dB and +32 dBm, respectively, working from a 3.3 V supply, with a peak power added efficiency (PAE) of 48%. Digital pre distortion (DPD) technique is used to enhance the PA linearity. The measured EVM for a 64-QAM OFDM signal is improved from -24 dB to -30 dB at +25 dBm output power. Compliance with the FCC 10 MHz WiMAX mask is demonstrated at +25 dBm of output power with power efficiency of ~25%. Under these conditions, the measured second harmonic level at the PA output is -31[dBm/MHz].