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A 380-MHz CMOS Linear-in-dB Variable Gain Amplifier with Gain Compensation Techniques for CDMA Systems
IEICE TRANSACTIONS on Electronics
Publication Date: 2003/06/01
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Devices and Circuits for Next Generation Multi-Media Communication Systems)
variable gain amplifier, VGA, gain compensation, temperature compensation, linear-in-dB characteristics, square circuit, MOSFET, square-law region, exponential-law region, CDMA,
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A linear-in-dB VGA of the current-divider type is fabricated in 0.25 µm CMOS technology. Two gain compensation techniques are proposed in order to compensate the gain deviations due to a MOSFET which has a square-law characteristic or an exponential-law characteristic determined by its current density. Temperature compensation techniques are also proposed. Measure results obtained at 380 MHz are a gain range of 80 dB, a gain error of 3 dB, and an NF of 11 dB.