T. Sasaki et al., GATE CURRENT CONTROL METHOD BY PULL-DOWN FETS FOR 0-28-DB GAAS VARIABLE ATTENUATOR IN DIRECT-CONVERSION MODULATOR-IC FOR 1.9-GHZ-PHS, IEICE transactions on electronics, E80C(6), 1997, pp. 794-799
We have developed 3 GaAs direct-conversion x 14 shifted QPSK modulator
IC equipped with variable attenuators for controlling the output powe
r level of the 1.4 GHz Personal Handy Phone system in Japan (PHS), The
IC was successfully demonstrated showing state-of-the-art performance
with the image rejection ratio of more than 36 dBc at a law input pow
er of -10 dBm in 1.9 GHz frequency range. By using the ''Gate Current
Control method by Pull-down FETs'' (GCCPF), the equipped attenuators v
ary the output power from 0 dB to -28 dB by 4 dB step. The TC operates
at a 7.7 V supply with power dissipation of 259 mW. The 2.6 x 4.6 mm(
2) chip with about 400 elements was fabricated by a 0.5 mu m WNx-gate
BPLDD GaAs MESFET process.