Cypress Semiconductor Corporation

Triton Technologies, Inc.

Crystal Semiconductor Corporation

I/o Sensors, Inc.

W. S. Henrion

W S Henrion

Matthew W Ip

Phillip J Kruczkowski

Donald A Kerth

Raymond K Erickson

Subhajit Sen

Hubert R Plumlee

A circuit, method, and network are disclosed herein to implement a voltage-controlled LC oscillator. The oscillator is configured having an LC tank circuit which is modulated by an in-phase modulating voltage. The modulating voltage can have a phase angle and amplitude that is controlled. Depending on the values of those control signals, the oscillating voltage will either increase or decrease current within the LC tank circuit and, thereby, increase or decrease the oscillating voltage respectively. Any number of phases can be connected together to produce signals of dissimilar phase angles. Preferably, those signals have phase angles of 0&deg;, 180&deg;, or even fractions thereof if an external circuitry is applied to the oscillation network.

System and method for controlling the frequency output from an oscillator using an in-phase voltage

An apparatus comprising a detector circuit and a first circuit. The detector circuit may be configured to (i) provide a bias voltage and (ii) generate a plurality of first signals and a plurality of second signals. The first circuit may be configured to (a) present (i) the bias voltage and (ii) a differential signal in response to the plurality of first signals and the plurality of second signals and (b) control (i) one or more of the plurality of first signals and (ii) one or more of the plurality of second signals.

Trans-impedance amplifier

An apparatus comprising an analog circuit, a passive circuit and a first circuit. The analog circuit may be configured to vary a voltage of an output signal in response to a first signal. The passive circuit may be configured to further vary the voltage. The first circuit may be configured to further vary the voltage. The first circuit generally comprises a parasitic capacitance. The passive circuit and the first circuit are generally coupled in series.

MOS load, pole compensation

A circuit and method used in LC or ring oscillators. The present invention may modulate the frequency of oscillation by detecting a quadrature signal and controlling the sign and magnitude of the quadrature signal that may be feedback to the oscillator to cause the oscillator to run either faster or slower (dependent on the sign of the quadrature signal) than the unmodulated oscillator.

Quadrature current frequency modulation oscillator

A sensor structure (10) has a central mass (16) mounted within a support structure comprising an outer support frame (18), and upper and lower plates or covers (12, 14). Eight L-shaped ribbon springs (32, 34) fit about the corners (28) of the mass (16) to mount mass (16) for movement from a reference position with respect to the support structure. One leg (38) of each spring (32, 34) is connected to an associated side (26A) of the mass (16) centrally of the length of the associated side (26A). The other leg (40) is connected to the outer support frame (18). The sensor structure is designed for use as a sensing mechanism in an electrostatic accelerometer arrangement.

Sensor structure with L-shaped spring legs

A analog calibration signal including at least one frequency component is generated by a very pure signal source, such as a digital oscillator and a digital-to-analog converter (DAC) that has been calibrated to be ultralinear. The analog calibration signal is converted by an analog-to-digital converter (ADC) to a digital signal. The digital signal is digitally compensated in accordance with compensation coefficients to produce a compensated digital signal. The compensated digital signal is digitally processed to isolate and measure distortion components, and the compensation coefficients are adjusted in response to the distortion components in order to reduce the distortion components. Feedback causes the distortion components to be minimized so that the compensation coefficients correct the nonlinearity in the analog-to-digital converter. Preferably the analog calibration signal is a two-tone signal, the digital signal is compensated by computing a polynomial, the compensation coefficients are coefficients of the polynomial, and the distortion components are intermodulation components. After calibration, the calibration coefficients can be adjusted to provide a specified non-linear transfer function. The method can also be used to compensate for nonlinearity in analog signal conditioning circuits that condition the analog signal prior to conversion. Moreover, the calibrated ADC could be used to re-calibrate the DAC, which could be used to re-calibrate the ADC, for enhanced linearity.

Analog-to-digital converter with digital linearity correction

Digital linearity correction is obtained by generating a digital calibration signal having at least one frequency component, converting the digital calibration signal to an analog signal, and detecting distortion in the analog signal generated from the calibration signal by nonlinearity to produce a compensation coefficient used to digitally compensate the digital input of the digital-to-analog converter. The compensation coefficient is adjusted in a feedback loop so that the distortion is minimized. Preferably the calibration signal has two frequencies, and the distortion is an intermodulation component having a substantially lower frequency. The intermodulation component, for example, is selected by an R-C low-pass filter, digitized by an analog-to-digital converter, and detected by digital signal processing. The analog-to-digital converter may have low resolution, low dynamic range and a low sampling rate. Preferably the digital compensation includes computing a third-order polynomial, and the intermodulation components for the second and third order terms are detected at about the same frequency. Preferably the offset of the digital-to-analog converter is calibrated first by setting the digital input to zero, modulating the analog output at about the same frequency, and adjusting the offset to eliminate any signal from the modulator. The calibration method can also be used to compensate for nonlinearity in signal conditioning circuitry, or to obtain a specified non-linear transfer characteristic.

Digital-to-analog converter with digital linearity correction

A transducer fabricated by micro-machining includes E-shaped leaf springs suspending a mass from a support. The transducer is formed by chemical etching through openings of opposite faces of a silicon wafer on which etch stop layer patterns are diffused. Sense and force conductive patterns are diffused onto opposite faces of the suspended mass. The legs of the E-shaped leaf springs are formed of a composite of a polysilicon base layer, a silicon dioxide insulating layer and a gold conducting layer. The thickness of such layers are selected to minimize bowing effects of the spring legs due to materials of different coefficients of thermal expansion. The spring-mass-support structure is sandwiched between opposite plates having corresponding force and conductive patterns which face such patterns on the suspended mass.

Micro-machined accelerometer with composite material springs

A spring-mass-support structure is arranged as an accelerometer with two electrostatic feedback loops so as to measure two components of acceleration. Two of such accelerometers are advantageously used on a submerged platform to determine the direction of a sound source in a body of water. One of such feedback loops of each accelerometer is used to measure low frequency gravitational acceleration applied to the platform as a result of the tilt of the platform due to the action of current and wave action of the water. The other of the feedback loops of each accelerometer measures sound wave induced acceleration on the platform. The gravitational acceleration of each accelerometer is used to compensate the higher frequency acceleration for the effect of tilt of the platform.

Micro-machined accelerometer with tilt compensation

The transducer is fabricated using micro-machining techniques of a silicon wafer. The transducer includes E-shaped leaf springs of silicon dioxide suspending a mass from a support. The transducer is formed by chemical etching through openings of opposite faces of a silicon wafer on which etch stop layer patterns are diffused. Sense and force conductive patterns are diffused onto the opposite faces of the suspended mass. The spring-mass-support structure is then sandwiched between opposite plates having corresponding sense and force conductive patterns which face such patterns on the suspended mass. Circuitry is provided by which a sense voltage and a force voltage are applied between opposite sense and force conductive patterns of the opposite plates creating a sense electric field and a force electric field across the sense and force patterns of the mass. A feedback circuit arrangement is provided to maintain the mass at a predetermined reference position between the support plates. Forward circuitry of the feedback arrangement produces a displacement signal in response to a voltage induced on the sense area of the mass as it moves in response to acceleration applied to the support structure. The feedback arrangement produces an amount of charge in response to the displacement signal which is applied to the force conducting area of the mass. The force on the mass is proportional to the product of that charge and the force electric field intensity which causes the mass to remain close to a reference position between the plates.

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Austin, TX, United States of America

W S Henrion