A NEW GAAS NEGATIVE VOLTAGE GENERATOR FOR A POWER-AMPLIFIER APPLIED TO A SINGLE-CHIP T R-MMIC FRONT-END/

A new GaAs negative voltage generator suitable for biasing a GaAs MESF ET power amplifier has been successfully developed and applied to a 1. 9-GHz single-chip transmit/receive (T/R)-MMIC front-end including a po wer amplifier, a T/R-switch, and so on. To meet various requirements n ecessary for integration with a power amplifier, four new circuit tech niques are introduced into this generator: (1) complementary charge pu mp operation to suppress spurious outputs, (2) an SCFL-to-DCFL cross-c oupled level shifter to ensure a wide operation Voltage range, (3) a l evel control circuit to reduce output voltage deviation caused by outp ut current, and (4) interface and layout designs to achieve sufficient isolation between the power amplifier and the generator. The generato r was incorporated into the MMIC front-end, and it was tested with a 3 0-lead shrink small outline package. With 20-to-500-MHz external input signals of more than -15 dBm, the generator produces negative Voltage s from -1.0 to -2.6 V for a wide range of supply voltages from 1.6 to 4.5 V. The current consumption is as low as 3.2 mA at 3 V. When a 22-d Bm output is delivered through the power amplifier biased by the gener ator, low spurious outputs below -70 dBc are achieved, and gate-bias v oltage deviations are suppressed to within 0.06 V even when a gale cur rent of -140 mu A flows through the amplifier. The generator also enab les high speed operation of charge time below 200 ns, which is effecti ve in TDMA systems such as digital cordless telephone systems. In layo ut design, electromagnetic simulation was utilized for estimating suff icient isolation between circuits in the MMIC. This negative voltage g enerator and its application techniques will enable GaAs high-density integration devices as well as single voltage operation of a GaAs MESF ET power amplifier.