Inmos Limited

Christopher Cytera

Andrew M Hall

A voltage controlled oscillator comprises a plurality of differential amplification stages each arranged to introduce a phase shift between its differential input signal and its differential output signal. The frequency at which the desired phase shift occurs can be controlled by adjusting the control signal Vc. The stages are arranged such that the output of one amplifier becomes the input to the next amplifier, making the phase shift additive. Further, a phase shift of 180.degree. may be introduced by inverting the output from one stage before inputting it to the next stage. The total phase shift introduced by the stages is 360.degree.. In this way, an oscillating signal of varying phase shift is produced at the output of each stage. Each stage comprises a standard differential amplifier, well known in the art, having a matched pair of p-channel transistors and a matched pair of n-channel transistors. The differential input is applied to each gate of the n-channel transistor pair, and the differential output is generated at the drains of the n-channel transistor pair.

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Grenoble, France

Christopher Cytera