smellyegg
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Posts: 5
Beijing, P.R. China
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The following VCO schematic( in the attachment) is used for gm-c filter automatic tuning, however, it doesnot oscillate. According to the theory, the last transconductor is used as a negative resistor, which maintains the oscillation, while the first two transconductors as well as the two capacitors are working as an inductor. When I adjust the value of C1 and C2, the output waveform doesnot change at all, however it should change, as the frequency of the output waveform is determined by gm/c.
Are there some special attentions that should be paid to while designing the three transconductors? Thanks.
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