Bell Telephone Laboratories

At&t Bell Laboratories

American Telephone & Telegraph Co., At&t Bell Laboratories

Harold Seidel

Norman Gerard Ziesse

George Elwood Smith

Wayne C Bowman

Edward H Nicollian

Randhir S Malik

Weyman B Suiter, Jr

A power converter includes an input primary switching system with its output connected to phase shift or impedance inversion circuit. These two circuits cooperate to function as a current source at the output of the impedance inversion circuit. A secondary switching system is connected in parallel with the output of the impedance inversion circuit and is switched synchronously with a controlled phase delay to the input primary switching system to synchronously charge a charge storage capacitor. The phase delay determines the voltage of the charge storage capacitor. An output load circuit is connected in parallel with both the output of the impedance inversion circuit and the input to the secondary switching system so that the capacitor voltage determined by the phase delay is controlling of the output voltage of the output load circuit.

Power converter having parallel power switching systems coupled by an

A voltage regulator circuit for a switching type converter operates by applying full power to the output if it falls below a reference value and zero power if the reference value is exceeded. The switching device of the voltage regulator is operated at a first high frequency and is periodically enabled to supply power to the output for discrete operative clock cycles at a second lower clock frequency in accord with the output signal level. An interval of off-time follows each operative cycle. In another embodiment operation of the switching devices is continuous, but power flow to the output is significantly reduced when the output voltage is overlimit.

Switching type voltage regulator with noncontinuous feedback

A self-oscillating power converter utilizes a MOSFET power transistor switch with its output electrode coupled to a tuned network that operatively limits the voltage waveform across the power switch to periodic unipolar pulses. The transistor switch may be operated at a high radio frequency so that its drain to gate interelectrode capacitance is sufficient to comprise the sole oscillatory sustaining feedback path of the converter. A reactive network which is inductive at the operating frequency couples the gate to source electrodes of the transistor switch and includes a variable capacitance as a means of adjusting the overall reactance, and hence the converter's switching frequency in order to provide voltage regulation. A resonant rectifier includes a tuned circuit to shape the voltage waveform across the rectifying diodes as a time inverse of the power switch waveform.

Self-oscillating high frequency power converter

An encoder (100) for processing an input signal to produce a ternary coded data stream having supressed DC comprises circuitry, and its associated methodology, including an arrangement (120,130,150) for augmenting the data stream with a compensating set of code symbols as determined by the number of positive and negative code symbols in the data stream as well as all prior compensating code symbols. A decoder (200) processes the received signal to extract the symbols in the data stream corresponding to the input signal. In order to achieve a preselected end-to-end transmission rate with the encoder-decoder combination, the rate of the signal propagated between encoder and decoder is increased to compensate for the appended code symbols.

DC Cancellation in ternary-coded data systems

Circuitry for converting a transfer function characteristic into a specified driving point impedance using feedforward techniques comprises: a directional coupler (90) having input, transmission and reflection ports; and unidirectional signal transfer means including transfer network (91) and amplifier (92) connected in cascade between the transmission and reflection ports. The impedance level of the transfer network is adjustable and is compensated for by the amplifier. A high impedance level allows for small element values for certain components such as capacitors so that a wide frequency band driving point impedance may be realized with integrated circuits. Further decrease in capacitor values is achieved utilizing capacitor magnification. The driving point impedance may be realized in balanced or unbalanced-to-ground fashion.

Driving point impedance derived from a transfer impedance

Circuitry (100) for providing impedance compensation between a source impedance (501) and a load impedance (505) which is proportional to the source impedance comprises: a pair of directional couplers (200 and 300), each coupler including bidirectional transmitting and receiving paths and a unidirectional path coupling these paths; means (121) for cascading the transmit path of one coupler to the receive path of the other; and unidirectional amplifier (400) for interconnecting the remaining bidirectional transmission ports. The impedance match to the source is obtained by adjusting the amplifier gain in correspondence to the number of essentially identical terminations that are bridged to form the load impedance. Means (510-515) sense the number of active terminations and transmit this information to the amplifier so the appropriate gain setting may be established.

Impedance matching using active couplers

Digital carrier channels and switching systems in a telecommunications facility may be used to transmit a high-speed data signal between an originating end and a terminating end. At the originating end, the high-speed data signal is distributed either bit-by-bit or sample-by-sample and sequentially to a predetermined plurality of lower speed channels. At the terminating end, the lower speed channels are collated to reconstruct the original high-speed data signal, using submessage sequence identifying signals.

Apparatus for and method of collating partitioned time disordered

Disclosed is a feedback regulated oscillator which comprises a reference signal source, a variable local oscillator, a converter responsive to the variable local oscillator for developing a signal, compatible with the signal of the reference source, having a magnitude which is responsive to the frequency of the local oscillator, and a comparator, responsive to the reference signal source and to the converter, for controlling the frequency of the variable local oscillator.

Precision frequency source using integrated circuit elements

An automatic equalizer for digital transmission systems is disclosed including a variable gain amplifier in one branch of a two-branch admittance circuit. The branch including the amplifier includes two frequency-dependent admittances while the other branch is insensitive to frequency. Varying the gain of the amplifier provides a minimum phase network which can be automatically adjusted to compensate for varying lengths and gauges of telephone pairs. This configuration permits digital transmission in the subscriber loop plant at rates up to 200 kilobits per second.

Automatic equalization for digital transmission systems

Improved signal to noise performance is obtained in an optical detector circuit (10) by impressing a high frequency (.omega..sub.p) pumping signal across a varactor photodetector (11) and extracting an output signal that includes the band of frequencies .omega..sub.p .+-..omega..sub.m, where .omega..sub.m is the maximum modulation frequency to be recovered by the detector. The modulation signal is recovered in an appropriate amplitude demodulator (15).

Parametric optical detector

A class of electronic hybrids is disclosed in which the line balancing impedance is made frequency-sensitive in order to better match the frequency characteristic of the connected line and is made voltage-controlled in order that a single network can be used to match a variety of different gauges of telephone cable pairs. The matching impedances are synthesized utilizing RC networks and the voltage control is realized with two-node Miller effect impedance multiplication circuits realized by long-tailed pairs for synthesizing hyperbolic tangent impedance functions under the control of a voltage.

Balancing impedance circuit

Electronic hybrid

Arc-cosine phase modulation is achieved by transforming the baseband signal with a tanh.sup.-1 transformation function, by modulating a carrier signal with a quadrature sum of two exponential signals related to the inverse hyperbolic tangent signal, and by hard limiting and filtering the modulated signal.

Arc-cosine phase modulators

Improved interferometric amplification is achieved by separating the input signal in accordance with the signal's projection on two orthogonal reference signals, with one of the reference signals capable of following the instantaneous frequency of the input signal. The separated signals are further separated into constant amplitude variable phase signal pairs defining the projected signals, and the constant amplitude signals are amplified and appropriately combined to form a signal that is in an amplified replica of the input signal.

Interferometric amplifier

A current measuring circuit comprising a signal sensitive element to which a portion of the measured current is coupled, which signal sensitive element has a readily measurable parameter that varies as a function of the signal applied thereto, and a measuring circuit capacitively coupled to the signal sensitive element for measuring the selected signal sensitive parameter.

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Warren, NJ, United States of America

Harold Seidel