Abstract: A precision digital phase shift element for achieving precise phase shift of an input pulse train signal. The output is a pulse train at a frequency equal to the input signal frequency divided by N, and having N equally spaced phase states. The relative phase state of the output signal is reliably controlled by selective deletion of pulses from the input signal pulse train. The selective deletion can be achieved by selectively gating the input pulse train, or by use of a dual modulus frequency divider circuit.

Abstract: A differential-type voltage-controlled oscillator (VCO) with low-frequency stability compensation is disclosed. The differential-type VCO comprises a voltage-to-current converter for converting an input voltage signal into a biasing current signal to control the frequency of the VCO output. The VCO further comprises a number of stages of differential amplifiers connected in cascade. Each of the stages of differential amplifiers includes a pair of differential input PMOS transistors, with each of the PMOS transistors connected to a pair of NMOS load transistors. Each of the pair of NMOS load transistors are connected in parallel. The VCO further comprises a number of stages of bias circuits connected in cascade. Each of the bias circuits is connected to a corresponding stage of the differential amplifiers for receiving the bias current generated by the voltage-to-current converter.

Abstract: A damping circuit is described which includes a phase-and-frequency detector, a charge pump, a voltage-current oscillator and a capacitor. The phase-and-frequency detector generates UP and DOWN signals representative of a difference in phase between a pair of digital input signals. The charge pump varies an amount of charge carried within the capacitor in accordance with the UP and DOWN signals. The voltage controlled oscillator generates an output signal having a frequency controlled by both a voltage provided by the capacitor and by the UP and DOWN signals directly received from the phase-and-frequency detector. No analog damping resistor is required. Rather, the damping circuit is an digital circuit which generates adequate phase and frequency damping without a damping resistor. Damping is achieved which is substantially unaffected by process parameters and operating and ambient parameters. Method embodiments of the invention are also described.

Abstract: A bias voltage generator for a voltage controlled oscillator is described. In one aspect of the invention, the bias voltage generator includes a biasing circuit to generate a minimum clock output at zero operating voltage, and includes a common mode rejection circuit for the BIASN and BIASP control voltages for the differential delay stages and a IDD test current shut-down circuit. A differential delay stage is described that includes a current source controlled by the BIASN and BIASP control voltages from the bias voltage generator, a resistance linearization circuit for current controlling transistors of a BIASN circuit, and a process variation circuit for compensating for temperature and process variations. The improved characteristics of the resulting VCO permits high frequency operation with a relatively low gain, relatively constant gain throughout operating voltage range, improved noise rejection capabilities, increased speed of delay stage, and reduced output signal swing.

Abstract: A clock deskewing apparatus uses either a series terminated single transmission line system or a Thevenin terminated dual transmission line system to deliver a clock signal to a load. A plurality of series terminated clock deskewing apparatuses are implemented, one for each load, so that the clock signal is delivered to all loads coupled to the clock signal simultaneously. Each series clock deskewing apparatus has a single termination resistor with the same impedance value as the transmission line that it is coupled to. Each Thevenin termination system has a voltage divider resistor network. A variable delay line within each series clock deskewing apparatus can be adjusted so that each load receives the clock signal at the same time. A programmable output driver impedance network can be used for the single line termination resistor of the series terminated clock deskewing system in order that the series terminated clock deskewing apparatus can be used with transmission lines having different line impedances.

Abstract: In a ring oscillator, a delay unit includes an input stage having a first and a second input port and a first and a second differential output port. At least two delay units are coupled together so as to form the ring oscillator. The delay unit further includes a first capacitor coupled to the first differential output port of each one of the delay units and a second capacitor is coupled to the second differential output port of the delay unit. A switching accelerator is coupled to the first and second capacitors so as to reduce the time it takes to switch between charged and discharged states for the capacitors.

Abstract: A voltage-controlled phase shift apparatus having an unlimited range for producing an output signal that varies in phase from an input signal by a predetermined phase difference. The phase shift apparatus includes a first delay circuit coupled to receive the input signal, the first delay circuit for outputting a first intermediate signal that is .alpha. degrees out of phase with the input signal, a second intermediate signal that is .beta. degrees out of phase with the first intermediate signal, a third intermediate signal that is 180 degrees out of phase with the first intermediate signal, and a fourth intermediate signal that is 180 degrees out of phase with the second intermediate signal.

Abstract: The present invention provides a phase shifting apparatus and method. The phase shifting apparatus comprises a signal generator and a converting device. An input signal is converted by the offset signals from the signal generator, thereby producing an output signal with the same frequency as that of the input signal. The phase of the output signal is determined by the difference of the offset signals applied to the converting device. In particular, when two offset signals are in quadrature, the output signal becomes in quadrature with the input signal. When the two offset signals have the same phase, the output signal has the same phase as that of the input signal. Preferably, the converting device includes two cascaded offset means, each having a multiplier and a filter coupling to the multiplier. A plurality of converting means may be coupled in parallel to the signal generator.

Abstract: A phase shifting circuit has an oscillation circuit. The oscillation circuit is provided with a charging and discharging capacitor at which the oscillation signal is generated. The oscillation signal has a constant level period and a saw tooth wave period. A valve of current flowing through the capacitor is changed in the middle of the saw tooth wave period by an input signal. An output of the phase shifting circuit is phase-shifted by 90.degree. with respect to the input signal.

Abstract: Disclosed is a clock distributing apparatus for distributing clock signals with a desired phase to each of devices provided between a clock generating section (10) for generating clock signals and a plurality of devices (30) for receiving the clock signals. A delay generating section (21) generates a plurality of delay clock signals by imparting a plurality of delay quantities to the clock signals from the clock generating section. A clock distributing section (22) has a plurality of input terminals corresponding to the plurality of delay clock signals and a plurality of output terminals corresponding to the respective devices. The clock distributing section (22) distributes desired delay clock signals to one or more output terminals by selecting the input terminals corresponding to the desired delay clock signals.

Abstract: A clock is phase shifted by an amount controlled by the value of a control signal by establishing at least several discrete delay times to be imposed on the clock. The control signal value controls selection of the imposed discrete delay time. An analog-to-digital converter of a phase locked loop responds to intelligence representing variable phase bits and the selected phase shifted clock to control the signal value. The selected replica is derived by at least several cascaded substantially equal time delay units. In one embodiment, a multiplexer responds to the clock, and the signal value, which is Gray coded, to control connections from one of the delay units to an output terminal. In another embodiment, the number of cascaded delay units interposed between the clock and an output terminal is controlled by the signal value.

Abstract: A phase shifter includes first and second single pole double throw switches, a low-pass filter, and a high-pass filter. The first switch has an input terminal and first and second output terminals, and the second switch has first and second input terminals and an output terminal. The low-pass filter is interposed between the first output terminal of the first switch and the first input terminal of the second switch and includes FETs as capacitors. The high-pass filter is interposed between the second output terminal of the first switch and the second input terminal of the second switch and includes a plurality of FETs as capacitors. The input terminal of first switch and the output terminal of the second switch are an input terminal and an output terminal of the phase shifter, respectively. Each of the high-pass filter and the low-pass filter produces two different phase quantities by the on-off switching of the FETs. Therefore, four different phase quantities are obtained in the phase shifter, i.e.

Abstract: A digital phase shifter is provided which uses a direct digital synthesizer. The digital phase shifter is provided with a digital phase-shifted waveform signal generator in which a plurality of digital phase-shifted waveform signals having different phase shifts are stored. The generator outputs a digital phase-shifted waveform signal corresponding to a specified phase shift from a phase shift specifying section in synchronism with an oscillation signal from a PLL circuit. The output is converted to an analog form by a D/A convertor to generate a phase-shifted waveform.

Abstract: A signal processing circuit delays a binary periodic input signal. Three series-connected delay devices produce output signals that are delayed in relation to the input signal. The delay of the delay devices can be controlled to a very high degree of accuracy, in that the delay devices include a plurality of mutually identical series-connected delay elements which are manufactured at one and the same time by common process steps in one and the same semiconductor process. A controller compares in a phase detector the phase of the input signal with the phase of the output signal from the last delay device, and on the basis thereof delivers control signals to the delay devices. These control signals control the delay devices in a manner such that an equal number of delay elements will be activated in each of the delay devices, such that the delay devices will have mutually the same delay.

Abstract: A bias voltage generator for a voltage controlled oscillator is described. In one aspect of the invention, the bias voltage generator includes a biasing circuit to generate a minimum clock output at zero operating voltage, and includes a common mode rejection circuit for the BIASN and BIASP control voltages for the differential delay stages and a IDD test current shut-down circuit. A differential delay stage is described that includes a current source controlled by the BIASN and BIASP control voltages from the bias voltage generator, a resistance linearization circuit for current controlling transistors of a BIASN circuit, and a process variation circuit for compensating for temperature and process variations. The improved characteristics of the resulting VCO permits high frequency operation with a relatively low gain, relatively constant gain throughout operating voltage range, improved noise rejection capabilities, increased speed of delay stage, and reduced output signal swing.

Abstract: The use of three identical delay line circuits enables one of said delay circuits to be connected as a minimum delay reference and a second delay circuit to then be continuously compared to said minimum delay reference delay circuit to provide a code which calibrates the second delay line circuit by indicating and controlling continuously the length of the second delay line circuit to provide an exactly 360-degree phase shift of the reference signal under variable temperatures, pressures and voltages. Then, by maintaining the length of the third identical delay line at said determined 360-degree length, and by being able to select any tap output of the third identical delay line circuit responsive to a command, the third delay line circuit provides an adjustable, feedback calibrated, delay line circuit.

Abstract: The present invention provides an output signal whose pulse width may be adjusted with respect to the pulse width of an incoming input signal. In particular, a plurality of signals is generated in response to the input signal. One of the plurality of signals is selected for controlling when the output signal transitions from a first logic state to a second logic state, and one of the plurality of signals is selected for controlling when the output signal transitions from a second logic state to a first logic state wherein the output signal has a pulse width being a function of the selection of the plurality of signals.

Abstract: The waveshaping functions provided by a summing resistor network and filter are performed by a waveshaping circuit that can be integrated with transceiving functions within a single integrated circuit. The waveshaping circuit utilizes the edges of an oscillator signal to generate a series of pairs of logic signals which have a defined timing relationship with respect to an input data signal. Each pair of logic signals is then utilized by a corresponding number of current stages to provide both an incremental portion of an output waveform and an incremental portion of a complementary output waveform. The pair of output waveforms can then be produced by summing together all of the incremental portions of the pair of waveforms.

Abstract: Apparatus for generating a phase startable clock signal, comprises an oscillator for providing a continuous sinusoidal input signal, a control signal source for providing a control input signal having a transition between a first state and a second state at a selected time during the signal epoch of the sinusoidal input signal, and a phase splitter, track and holds, multipliers and a summation device for operating on the sinusoidal input signal with the control input signal to produce a sinusoidal output signal commencing with a predetermined phase at a predetermined time relative to the transition.

Abstract: The invention provides a digital PLL circuit wherein the integration time constant of a random walk filter can be varied adaptively in response to a frequency error. A master clock signal having a frequency equal to N (integral number) times that of an input clock signal is normally divided by N by a divider, and the division output of the divider and the input clock signal are compared in phase with each other by a phase comparator. The dividing ratio of the divider is temporarily varied in accordance with a result of the comparison so as to make the phases of the division output and the input clock signal coincide with each other to establish synchronism between them.

Abstract: The invention relates to a clock recovery for a digital data signal. A phase detector receives the data signal and transmits it after clock recovery. A phase correcting device creates and transmits, by means of a number of auxiliary clock signals phase shifted with respect to each other and originating from an incoming clock signal (CK.sub.in), a recovered clock signal (CK.sub.out) for the data signal. The recovered clock signal is fed to the phase detector, which detects a phase position error, if any, between the data signal and its recovered clock signal and emits information regarding this to the phase correcting device.

Abstract: A circuit eliminates clock skew between an off-chip clock signal originating off an integrated circuit and an on-chip clock signal produced on the integrated circuit. The on-chip clock signal is produced by phase delaying the off-chip clock signal. A first delay path and a second delay path each phase delay the off-chip clock signal an identical amount. A multiplexor selects one of the delay paths to produce the on-chip clock signal. When phase delay through the first delay path is adjusted, the multiplexor selects the second delay path. When phase delay through the second delay path is adjusted, the selection means selects the first delay path. A phase detector and filter circuit generates control signals which indicate, based on phase difference between the off-chip clock signal and the on-chip clock signal, when to increase and when to decrease the phase delay through the delay paths.

Abstract: A clock signal supply system is disclosed for a semiconductor device with a semiconductor chip and a wiring substrate connected in flip-chip fashion and an optical waveguide interposed in the space between electrode members, in which the mutual arrangement of the electrical interconnection and the optical waveguide interconnection on the wiring substrate is not affected and can be used separately from each other for different applications, thereby improving the throughput of the interconnections as a whole.

Abstract: A digital-to analogue converter for producing an RF output signal proportional to a digital input word of N bits from an RF reference input, N being an integer greater or equal to 2. The converter comprises a plurality of power splitters, power combiners and a plurality of mixers or RF switches connected in a predetermined configuration.

Abstract: A damping circuit is described which includes a phase-and-frequency detector, a charge pump, a voltage-current oscillator and a capacitor. The phase-and-frequency detector generates UP and DOWN signals representative of a difference in phase between a pair of digital input signals. The charge pump varies an amount of charge carried within the capacitor in accordance with the UP and DOWN signals. The voltage controlled oscillator generates an output signal having a frequency controlled by both a voltage provided by the capacitor and by the UP and DOWN signals directly received from the phase-and-frequency detector. No analog damping resistor is required. Rather, the digital damping circuit is a digital circuit which generates adequate phase and frequency damping without a damping resistor. In this manner damping is achieved which is substantially unaffected by process parameters and operating and ambient parameters. Method embodiments of the invention are also described.

Abstract: A synchronous delay line (SDL) for generating delayed signals synchronized with a clock signal is described. The present SDL includes a phase generator and a plurality of serially coupled voltage controlled delay elements. The phase generator takes the clock signal and generates a first trigger signal and a second trigger signal, which are substantially deskewed with respect to each other. Each of the delay elements receives two trigger inputs and outputs a delayed signal and two trigger outputs. The first and second trigger signals are coupled to one of the delay elements as trigger inputs. Each transition of the first and second trigger signals triggers the propagation of two waves through the delay line. The present SDL has a minimum tap-to-tap delay of only one inverter delay, versus a minimum tap-to-tap delay of two NAND gates in prior SDLs. Thus, the present SDL provides for double the number of output taps, and hence, double the resolution as compared to prior SDLs.

Abstract: A method and apparatus for low power clock generation for high speed applications includes a divider for receiving a high frequency input signal and producing a low frequency input signal controlled to a high resolution. A numerically controlled oscillator (NCO) is coupled to the divider and receives a frequency word and the input signal and produces a phase advance command. The phase advance command is used to produce an output transition command. The output transition command is executed in a phase shifter in response to a phase advance/retard polarity input and a high frequency clock input signal. The phase shifter produces a low-frequency output clock signal.

Abstract: An output pad for an integrated circuit includes circuitry to align the output with an on-chip clock signal, and to compensate the output such that it remains coincident with the on-chip clock signal even when changes occur in power supply voltage, manufacturing process and temperature. This output pad has a closed-loop feedback circuit which controls the delay of the output signal through a variable delay element. The loop adjust the delay until the clock edge of the on-chip clock signal is coincident with the output signal within a defined tolerance. The output pad self-compensates with every clock cycle, which is many times faster than any induced variation.