CMOS Broadband Programmable Gain Active Balun With 0.5-dB Gain Steps

This paper presents a CMOS broadband programmable gain active balun (PGAB) that demonstrates seven digitally controlled gains with 0.5-dB gain steps separately for plus and minus output ports. The PGAB was designed and fabricated in a 130-nm RFCMOS process. For the maximum gain state, the measured gains of the plus and minus ports are 0.0 and 1.1 dB at 2 GHz. The operating frequency range is from 1.0 to 8.0 GHz by 0.3-dB gain step error, and it is from 1 to 13.0 GHz by 3-dB gain attenuation. For the maximum gain state, the measured amplitude imbalance and phase imbalance from 1 to 16 GHz are less than 1.4 dB and 4.1 ^°, respectively. The measured input return losses are better than 13.5 dB, and the output return losses are better than 18.5 dB for all controlled gain states from 1 to 16 GHz. The measured IP1dB at 7 GHz is 6.1 dBm. The measured noise figures for the plus and minus ports from 2 to 14 GHz are less than 11.2 and 10.2 dB, respectively. The supply voltages are 3.0 and 1.5 V, and the measured power consumption is 93 mW. The core area of the fabricated integrated circuit is 0.38 mm × 0.36 mm.