Varactor_tuned_Wien_bridge_oscillator

Published:2009/7/24 7:26:00 Author:Jessie | From:SeekIC

This circuit replaces the lamp (Fig. 5-18) and electronic control (Fig. 5-19) with a Wien network to produce a variable-frequency output from 1 to 10 MHz. Usually, Wien circuits require manually adjustable elements (dual pots or two-section variable capacitors) for tuning. In this circuit, the Wien-network resistors are fixed (360Ω), and the capacitive elements are accomplished with varactor diodes. The circuit is tuned by a control voltage at the noninverting input of A3. Figure 5-20B is a spectrum analysis of the oscillator output. Linear Technology corporation, 1991, AN47-51.



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