An X-band single-pull class A/B power amplifier in 0.18 μm CMOS

We report a compact single-pull X-band power amplifier (PA) operating at the class AB utilizing on-chip transformers in 0.18-μm 1P6M CMOS technology. Designed X-band PA includes the interstage matching network and the output power combiner by utilizing on-chip transformers to achieve small area occupation with improved power added efficiency (PAE). A series RC network is employed between gate and drain of the MOS to provide stable operation with improved bandwidth. The designed PA measures the saturated output power of 18 dBm while the achieved power gain is 19.2 dB at 8 GHz. The output 1-dB gain compression point (OP1dB) is 14.9 dBm, and the peak PAE is measured to be 22.6% under the supply of 1.8 V. The core chip size is 0.43 mm ² excluding the pads.