Voltage controlled oscillators

摘要

A voltage controlled oscillator (VCO) is provided which comprises: a tank circuit; an amplifier comprising a number of switchable amplifier elements (8, 10, 12); and means for switching each amplifier element (8, 10, 12) on or off depending on the frequency at which the VCO is oscillating, so as to maintain the transconductance of the amplifier elements (8, 10, 12) within certain limits.