Calibratable adaptive antenna combiner at 5.2 GHz with high yield for laptop interface card

This paper presents a calibratable adaptive antenna combiner with three bra nches for high-performance radio local area network at 5.2 GHz. The system was mounted on a reinforced duroid substrate and enables the integration in a laptop interface card. Each branch consists of a bent stacked slot anten na, a low-noise-amplifier monolithic microwave integrated circuit (MMIC) wi th antenna/calibration switching and a vector modulator MMIC with an amplit ude control range of 15 dB and 360 degrees phase control range. The signals of the three branches are combined by an active adder MMIC. A calibration is proposed to significantly improve the phase and amplitude control resolu tion and the yield of the designed MMIC circuits, which were fabricated usi ng a commercial GaAs process. Each branch has a maximum power gain of 16 dB , a noise figure of 3.3 dB, and a 1-dB output compression point of -4 dBm. The whole system draws less than 28 mA from a 2.7-V voltage supply. The tot al required MMIC chip size is 10.8 mm(2).