Analog Devices,inc.

Ronald Bryce Gray, Iii

Ahmed Mohamed Abdelatty Ali

Huseyin Dinc

George F Diniz

One embodiment is an apparatus including a detector circuit electrically coupled between a signal source and a second circuit, the signal source generating a first signal, the detector circuit detecting a level of the first signal and generating a first control signal when the detected level of the first signal exceeds a first threshold value, and a clamping switch electrically coupled to receive the first control signal from the detector circuit, the clamping switch including a multi-terminal active device. The first control signal controls a state of the clamping switch such that the clamping switch clamps a level of a signal applied to the second circuit when the level of the first signal exceeds the first threshold value.

Signal level detection and overrange signal limiter and clamp for electronic circuits

CMOS reference structures (e.g., voltage, current and resistance structures) are provided that are substantially insensitive to temperature, supply voltages and track fabrication processes. The structures include a V.sub.t -referenced source, a sensor and a summer. The source generates a source voltage and a feed-forward current that may have an error term and the sensor generates a feedback current that has a correction term that substantially offsets the error to stabilize a sum current. In different structure embodiments, voltage, current and resistance references are responsive to the stabilized sum current. The source, sensor and summer are preferably realized with MOSFETs whose channel width-to-length ratios are chosen to enhance the temperature insensitivity of the references.

Temperature, supply and process-insensitive CMOS reference structures

Signal-controlled oscillator structures are provided that are substantially insensitive to temperature, supply voltages and fabrication processes. They include a plurality of time-delay stages that are serially connected in a closed feedback ring and each of the stages includes an amplifier, at least one capacitor and at least one signal-controlled impedance element that couples the capacitor to the amplifier. Accordingly, the frequency of the oscillator is a function of a control signal applied to the impedance elements of the stages. In an oscillator embodiment, each of the amplifiers is a differential pair of transistors, the capacitor comprises first and second capacitors and the signal-controlled impedance element comprises first and second coupling transistors that each couples a respective one of the capacitors to a different side of the differential output. Preferably, first and second triode-biased load transistors are each coupled to a different side of the differential output and biased by a voltage reference which has a Vt-referenced source, a sensor and a summer. The source generates a source voltage and a feed-forward current, the sensor generates a feedback current that corrects the feed-forward current and the summer sums the feed-forward current and the feedback current into a sum current and generates a reference voltage that is responsive to the sum current. Accordingly, changes in the feed-forward current are corrected by changes in the feedback current so that the sum current and the reference voltage are substantially constant.

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Oak Ridge, NC, United States of America

Ronald Bryce Gray, Iii