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 hi gh-performance radio local area networks at 5.2 GHz is presented in this pa per, low power consumption is achieved using a 0.6-mum 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 fu ll 360 degrees phase control range is achieved by combining two of the thre e vectors, which have phase offsets of 120 degrees, with variable amplitude . Chip size is only 1.3 mm(2). The proposed vector modulator applies a new circuit configuration of variable-gain amplifiers to compensate their trans mission phase errors. Within a gain control range of 20 dB, the phase error can he reduced to +/-3 degrees, which is about a factor of eight better th an the results obtained by single FET amplifiers, A simple calibration proc edure for the proposed vector modulators is presented to improve the manufa cturing yield and to decrease the impact due to temperature changes and agi ng. A maximum gain error of +/-0.8 dB and a maximum phase error of +/-7 deg rees has been measured after applying this calibration to the designed vect or modulator.