An antenna diversity MMIC vector modulator for HIPERLAN with low power consumption and calibration capability

The design and performance of a vector-modulator-based phase shifter for high-performance radio local area networks at 5.2 GHz is presented in this paper. Low power consumption is achieved using a 0.6-/spl mu/m GaAs MESFET process. At a voltage supply of 1.4 V and with a current consumption between 3.5-7 mA, the gain is 0.6 dB and the 1-dB input compression point is -9 dBm. A full 360/spl deg/ phase control range is achieved by combining two of the three vectors, which have phase offsets of 120/spl deg/, with variable amplitude. Chip size is only 1.3 mm/sup 2/. The proposed vector modulator applies a new circuit configuration of variable-gain amplifiers to compensate their transmission phase errors. Within a gain control range of 20 dB, the phase error can be reduced to /spl plusmn/3/spl deg/, which is about a factor of eight better than the results obtained by single FET amplifiers. A simple calibration procedure for the proposed vector modulators is presented to improve the manufacturing yield and to decrease the impact due to temperature changes and aging. A maximum gain error of /spl plusmn/0.8 dB and a maximum phase error of /spl plusmn/7/spl deg/ have been measured after applying this calibration to the designed vector modulator.