Sgs-thomson Microelectronics Limited

Inmos Limited

Stmicroelectronics Gmbh

Andrew M Hall

Trevor K Monk

Christopher Cytera

A ring oscillator having an odd number of single ended stages, each stage including two transistors connected as a current mirror. The stage provides for low-voltage performance and improved process tolerance characteristics.

Ring oscillator using current mirror inverter stages

Frequency Doubler

Low voltage high frequency ring oscillator for controling phase-shifted

A quadrature oscillator is provided constructed of NOR gates in the manner of a non-linear circuit which is inherently unstable and which cycles sequentially through four distinct states at a rate determined by the constitution of the NOR gates. The quadrature oscillator includes first and second stages that each include first and second NOR gates. The output of the first NOR gate of the first stage is connected as an input to the second NOR gate of each of the first and second stages. The output of the second NOR gate of the first stage is connected as an input to the first NOR gate of each of the first and second stages. The output of the first NOR gate of the second stage is connected as an input to the first NOR gate of the first stage and the second NOR gate of the second stage. The output of the second NOR gate of the second stage is connected as and input to the second NOR gate of the first stage and the first NOR gate of the second stage. Each of the NOR gates includes first and second input transistors that each have a control node for receiving an input signal and a controllable path between an output node and a reference voltage, a diode-connected transistor connected between the output node and the reference voltage, and a current source connected to the output node.

Quadrature oscillator having a variable frequency

A switching circuit for an FET transistor includes a controlled current circuit coupled to the gate of the FET. The input to the controlled current circuit represents a desired rate of change of gate voltage of the FET and is generated by a circuit responsive to the average specific transconductance of two FETs of similar specific transconductance operating at different drain circuit densities.

Output noise reduction circuit

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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Edinburgh, United Kingdom

Andrew M Hall