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A temperature-stable CMOS variable-gain amplifier with 80-dB linearly controlled gain range

2002; Institute of Electrical and Electronics Engineers; Volume: 37; Issue: 5 Linguagem: Inglês

10.1109/4.997847

1558-173X

Takafumi Yamaji, N. Kanou, Tetsuro Itakura,

Advancements in Semiconductor Devices and Circuit Design

A CMOS variable-gain amplifier (VGA) using subthreshold exponential region transistors with master-slave control technique is proposed. The proposed technique is applied to an intermediate-frequency VGA with a quadrature demodulator for wireless receivers. The test chip is fabricated using a 0.25-/spl mu/m CMOS technology. An 80-dB linearly controlled gain range is achieved with exponential voltage-to-current converters using MOS transistors biased in a subthreshold exponential region, and the master-slave control circuits make the gain-control characteristic insensitive to the temperature. The experimental results indicate that the proposed technique is effective for a CMOS variable-gain amplifier.