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A New GaAs Negative Voltage Generator for a Power Amplifier Applied to a Single-Chip T/R-MMIC Front-End
IEICE TRANSACTIONS on Electronics
Publication Date: 1996/12/25
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Semiconductor Materials and Devices
negative voltage generator, GaAs MESFET, power amplifire, MMIC front-end,
Full Text: PDF(1MB)>>
A new GaAs negative voltage generator suitable for biasing a GaAs MESFET power amplifier has been successfully developed and applied to a 1.9-GHz single-chip transmit/receive (T/R)-MMIC front-end including a power amplifier, a T/R-switch, and so on. To meet various requirements necessary for integration with a power amplifier, four new circuit techniques are introduced into this generator: (1)complementary charge pump operation to suppress spurious outputs. (2)an SCFL-to-DCFL cross-coupled level shifter to ensure a wide operation voltage range, (3)a level control circuit to reduce output voltage deviation caused by output current, and (4)interface and layout designs to achieve sufficient isolation between the power amplifier and the generator. The generator was incorporated into the MMIC front-end, and it was tested with a 30-lead shrink small outline package. With 20-to-500-MHz external input signals of more than -15 dBm, the generator produces negative voltages from -1.0 to -2.6 V for a wide range of suppiy voltages from 1.6 to 4.5 V. The current consumption is as low as 3.2 mA at 3 V. When a 22-dBm output is delivered through the power amplifier biased by the generator, low spurious outputs below -70 dBc are achieved. and gate-bias voltage deviations are suppressed to within 0.06 V even when a gate current of -140 µA flows through the amplifier. The generator also enables high speed operation of charge time below 200 ns, which is effective in TDMA systems such as digital cordless telephone systems. In layout design, electromagnetic simulation was utilized for estimating sufficient isolation between circuits in the MMIC. This negative voltage generator and its application techniques will enable GaAs high-density integration devices as well as single voltage operation of a GaAs MESFET power amplifier.