Abstract: A control scheme for operating an oscillator/counter A/D converter (10) so that it simultaneously provides frequency downconversion, band pass filtering and analog-to-digital conversion of an analog signal, where the analog signal includes a carrier wave modulated with information by any known modulation technique. The converter (10) uses a superconducting, Josephson single flux quantum circuit operating as a voltage controlled oscillator (12). The voltage controlled oscillator (12) receives the analog signal to be converted, and generates a series of sharp, high frequency pulses based on the characteristics of the carrier signal. The series of pulses are applied to a gate circuit (14) that either passes or blocks the pulses depending on a gate control signal. When the pulses are passed by the gate circuit (14), a counter circuit (16) accumulates the pulses during a sampling period.

Abstract: Differential switching circuitry, for use for example in a digital-to-analog converter, includes: a first switch element (S1) connected between a common node (CN) and a first output node (OUT1), and a second switch element (S2) connected between the common node (N) and a second output node (OUT2). First and second driver circuits (12, 14) correspond respectively to the first and second switch elements, each driver circuit switching its corresponding element ON and OFF in dependence upon an applied input signal (IN1, IN2). The driver circuits co-operate such that one switch element is ON when the other is OFF. Each switch element (S1, S2) is paired with a matching element (46, 44) in the other switch element's driver circuit. That matching element (e.g. 44) is coupled operatively to its paired switch element's driver circuit (14) and is matched, e.g.

Abstract: A digital phase measuring system and method for measuring the phase difference between two signals including generating quadrature clock signals for a first reference signal, converting a second measured signal from analog to digital form by sampling the second measured signal using the quadrature clock signals to produce quadrature cartesian samples of the measured signal, and converting the quadrature cartesian samples to polar coordinates to define the polar phase coordinate representative of the phase difference between the two signals.

Abstract: Analog memories such as CCD, which are advantageous in less power consumption and higher integration density, are used to configure a system for highly accurately executing digital/analog processing. A digital to analog converter according to the invention has at least one first analog memory having an input port for receiving input signal packets and a partial output drive port for driving the i-th output signal packet; at least one second analog memory having a function to integrate input signal packets applied thereto; and at least one signal packet routing mechanism for selectively routing output signal packets from the first analog memory according to an input digital signal bit. The extremely simple configuration of the present invention may be effectively utilized for realizing an ultra-parallel analog processor as well as applied to other fields such as video processing by combining a function of an input means for optical signals, which has been a main application of the CCD.

Abstract: An architecture for oversampled delta-sigma (.DELTA.--.SIGMA.) analog-to-digital (A/D) conversion of high-frequency, narrow-band signals includes multistage .DELTA.--.SIGMA. modulators that incorporate band-reject noise shaping centered at an arbitrary center frequency F.sub.bp. These modulators cascaded with a bandpass digital filter centered at the arbitrary center frequency F.sub.bp perform A/D conversion for high-frequency, narrow-band signals having the same arbitrary frequency. The bandpass modulators are implemented by use of resonators which provide a substantially large gain at the arbitrary frequency.

Abstract: A method and apparatus for digital-to-digital conversion using sigma-delta modulation of the temporal spacing between digital samples. The method and apparatus of the present invention provides for sigma-delta modulation of the time base such that noise produced by non-uniform sampling are frequency-shaped to a region (i.e., shifted to higher frequencies) where it can be removed by conventional filtering techniques. In one embodiment, the digital data is interpolated by fixed ratio and then decimated under control of a sigma-delta modulated frequency selection signal that represents, on average, the data rate of the incoming digital data stream. Thereafter, the digital data is interpolated under control of a sigma-delta modulated frequency selection signal that represents, on average, the data rate of the digital data to be output by the converter and then decimated by a fixed ratio. The first and second frequency signal selection numbers are modulated using n-th order m-bit sigma-delta modulators.