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Article: Variable-gain amplifier lowers noise and distortion but keeps bandwidth at 35 MHz. (Analog Devices Inc.'s AD600 and AD602 voltage-controlled amplifiers) (product announcement)
- Article from:
- EDN
- Article date:
- October 10, 1991
- Author:
CopyrightCOPYRIGHT 1991 Reed Business Information, Inc. (US). This material is published under license from the publisher through the Gale Group, Farmington Hills, Michigan. All inquiries regarding rights should be directed to the Gale Group. (Hide copyright information)
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Most voltage-controlled amplifiers use some sort of nonlinear circuit element directly in the signal path. These nonlinear elements increase distortion and noise and often force bandwidth tradeoffs as you vary the gain. The internal architecture of the AD600 and AD602 prevents you from having to make this tradeoff and also provides low input noise of 1.4 nV/[square root of Hz], and low-distortion performance of -60 dBc at outputs of [+ or -] 1V. The amplifiers' typical 3-dB bandwidth is 35 MHz and is essentially independent of the gain setting. The dual-channel AD600 and AD602 provide gain ranges of 0 to 40 dB and -10 to +30 dB, respectively.
A 2-stage design ...