Abstract: The integrated circuit has a clock input for an external clock signal and an output unit controlled by an internal clock signal in a normal mode of operation to output data to a data output. In addition, the integrated circuit has a control unit generating the internal clock signal from the external clock signal. The control unit has a phase shift unit that, in the normal mode of operation, effects a phase shift of the internal clock signal generated by the control unit with respect to the external clock signal. In addition, the integrated circuit has a detector unit determining the capacitive load on the data output. The detector unit supplying the phase shift unit with a corresponding detector signal on the basis of which the phase shift is set.

Abstract: A semiconductor device includes a timing-stabilization circuit which adjusts a phase of the synchronization clock signal. The semiconductor device further includes a control circuit which suspends the adjustment of the phase of the synchronization clock by the timing-stabilization circuit during a time period when the data is output from an output circuit.

Abstract: A semiconductor integrated circuit comprises a phase control unit for shifting the phase of an input signal by two or more different fixed phases so as to generate two or more output signals out of phase. A phase detector detects phase differences among the two or more output signals from the phase control unit, and generates one or more correction signals each having a value corresponding to a deviation of one of the detected phase differences from a desired phase difference. The phase detector feeds the one or more correction signals back to the phase control unit so as to make the detected phase differences equal to desired phase differences, respectively.

Abstract: The present invention is embodied in a clock controller for generating and controlling the phase alignment of a plurality of ratioed sub-clocks. A master clock is preferably input to a clock splitter to provide a plurality of slave clocks. Phase holds, generated from the slave clocks, are then used to gate each of the slave clocks to produce ratioed clocks that produce phase aligned clock pulses at integer factors of the master clock frequency. The clock controller controls the ratioed clocks by processing commands to start, stop, or pulse the ratioed clocks.

Abstract: This invention provides a phase splitter device that generates in-phase and quadrature outputs that have a phase difference of substantially a phase set value (e.g., 90°) and an amplitude difference of substantially an amplitude set value (e.g., zero). A first feedback loop controls the phase difference between the in-phase and the quadrature outputs while a second feedback loop controls the amplitude difference between the in-phase and quadrature outputs. The phase splitter device controls the amplitude difference and the phase difference between the in-phase and the quadrature outputs by a common mode of control signals and a differential between the control signals, respectively. In this way, the phase splitter device generates in-phasing and quadrature outputs that have a phase difference and an amplitude difference that is substantially equal to the amplitude and phase set values (e.g., zero and 90°) using a single set of control signals.

Abstract: A broadband phase-shifting circuit, in particular for an IQ modulator, has two phase-shifting branches connected in parallel, to the input of which is supplied the input signal of which the phase is to be shifted, and which supply at their outputs output signals of which the phase is shifted over a predetermined angle, in particular of 90°. The phase shifter of one phase-shifting branch is controlled depending on the frequency of the input signal in such a way that the phase angle between the two output signals approximately corresponds to the desired value (coarse control), whereas the phase shifter of the other phase-shifting branch is set to the desired phase angle (fine regulation by a phase detector connected between the outputs of the two phase-shifting branches.

Abstract: A method of controlling a clock, including the steps of (a) receiving an external clock signal, (b) calculating a first period of time defined as (T1-T2) wherein T1 is a cycle of the external clock signal, and T2 is a period of time during which the external clock signal is transmitted through devices generating skew to the external clock signal, (c) stopping the external clock signal to be transmitted by the first period of time, and (d) driving the external clock signal to thereby turn the external clock signal into an internal clock signal. The method makes it possible to detect delay in a clock signal, and generate no delay error inherent to a digital circuit.

Abstract: A receiving system for aligning a first signal to a reference signal is disclosed. In the receiving system, a selectable delay receives a first signal and delays the first signal by a selectable amount to generate a delayed first signal. A phase detector receives the delayed first signal and a reference signal and generates phase information which represents a phase difference between the delayed first signal and the reference signal. A phase accumulator receives and accumulates the phase information and generates delay select information which represents an accumulated phase difference between the delayed first signal and the reference signal. The selectable delay receives the delay select information and delays the first signal based on the delay select information, resulting in improved alignment of the delayed first signal and the reference signal. The receiving system may also include a second delay for receiving a second signal and delaying it by a fixed amount to generate the reference signal.

Abstract: A phase adjustment circuit of the present invention includes a plurality of input terminals which input a plurality of clock signals, respectively, and a plurality of first elements which input the clock signals, respectively, and adjust the clock signals, respectively. The phase adjustment circuit has a second element which compares the phase of a reference clock signal and the phase of an output signal from one of the first elements and outputs a compared result. A third element inputs the compared result and controls each of the first elements based on the compared result.

Abstract: A gated-delay locked loop that generates an output clock in phase with and having a frequency which is an integer multiple of the frequency of a reference clock. The gated delay-locked loop includes a voltage-controlled gated oscillator having first and second serially connected voltage-controlled delay elements that each introduce a time delay to produce a first delayed clock and the output clock. An S-R flip-flop receives the first delayed clock on its R-input and either the output clock or the reference clock on its S-input to produce a loop clock. The loop clock is provided to the first delay element. A multiplexer selects the reference clock as the S input to the flip-flop once every N cycles, and selects the output clock as the S input the remaining N−1 cycles. A phase detector, a charge pump and a loop filter compare the phase of the output clock to the phase of the reference clock and apply a voltage to the delay elements to correct any phase differences.

Abstract: An integrated circuit includes a first adjustable delay unit to which a first clock signal is fed and a second adjustable delay unit to which a second clock signal is fed. A phase detector is connected to the input and to the output of the first delay unit. A control unit serves for correcting a phase difference obtained by the phase detector and controls the delay time of the first delay unit in a corresponding manner. The control unit additionally sets the delay time of the second delay unit to essentially the same value as that of the first delay unit. Furthermore, the output of the second delay unit is connected to the input of a third adjustable delay unit.

Abstract: The disclosure describes a multi-stage phase comparator and a phase-locked loop incorporating such a comparator. The comparator measures a phase difference between a reference signal and an output signal using a periodic clock. The comparator is a two stage comparator comprising a fine and coarse comparator. The coarse comparator measures the number of full clock periods between a transition of the reference signal and the output signal. The fine comparator comprises a delay line generator that generates a plurality of delayed clocks. The delayed clocks are used to over sample the reference signal to determine a fine phase difference representing a remaining fraction of the clock period, between transitions of the reference and output signals. A phase locked loop using the multi-stage comparator allows for more accurate phase locking.

Abstract: An integrated delay line calibration method and apparatus are provided for a direct access storage device (DASD). A delay line, such as used in a direct access storage device (DASD) is calibrated by configuring the delay line as a ring oscillator for calibration. A delay line ring frequency is compared to a reference frequency. The delay of the delay line is adjusted until the delay line ring frequency and the reference frequency are equal. Each delay block within the delay line is controlled by a delay adjust digital-to-analog converter (DAC). A control logic circuit couples N-bit words to the delay adjust digital-to-analog converter (DAC) for calibration adjustment of the delay line delay.

Abstract: A clock signal generator includes a phase shifter for generating four clock signals having phases consecutively shifted from one another by 90 degrees based on an external clock signal, a mixer for mixing two of the four clock signals to output an internal clock signal, and an initializing circuit for selecting consecutively one and another of the four clock signals as an internal clock signal in an initializing period. A phase comparator compares the internal clock signal against the external clock signal in the initializing period to determine which of the internal clock signal and the external clock signal leads. The initializing circuit reduces the time length for locking of the internal clock signal to the external clock signal in an operational period of the mixer.

Abstract: A duty cycle control buffer uses an edge detector input stage to detect the transitions of an unpredictable clock signal input. The edge detector generates one shot output signals in synchronism with the clock signal. A pulse width controllable monostable multivibrator converts the one shot signals into rectangular pulses, at the same frequency as the original clock input. The rectangular pulses are inverted and then averaged, to provide a voltage input to one side of an operational amplifier. A reference voltage is supplied to the other side of the operational amplifier, such that the difference between the average voltage and the reference voltage generates an output control voltage from the operational amplifier. This control voltage provides negative feedback to a pulse width control stage within the monostable multivibrator, thereby adjusting the pulse width of the rectangular pulse output until a steady state is reached.

Abstract: A fractional period delay circuit to delay a clocking signal by a non-integer fraction of the period of the clocking signal is disclosed. The fractional period delay circuit has a first delay line connected to a master timing signal to delay the master clock to form the first timing signal. The fractional period delay circuit has plurality of adjustable delay lines. Each adjustable delay line is connected to the master timing signal to delay the master timing A delay adjustment input will modify the delay of the adjustable delay circuit. The fractional period delay circuit further has a plurality of phase difference detectors connected to the output of the first delay line and to the output of one of the plurality of adjustable delay lines. The phase difference detector will create a difference signal indicating a difference in phase between the first timing signal and one of the delayed timing signals. A plurality of sequence timing signals are created in a is timing sequence generator.

Abstract: A circuit and method for compensating for the output phase delay of an external clock signal utilizes a phase-locked loop that includes an output port of an integrated circuit device. In the phase-locked loop, a phase detecting circuit compares the external clock signal with an output signal from the output port, producing a phase error signal. The phase error signal is applied to a skew compensator to generate an internal clock signal. The internal clock signal is fed back through the output port to the phase detecting circuit. Clock jitter is reduced by reducing the gain of the skew compensator after a phase lock condition occurs in the compensation circuit.

Abstract: An apparatus for adjusting phase relation of a plurality of clock signals in a processor. The apparatus contains a phase detection circuit that receives a plurality of clock signals and generates a first output based on a phase relation between those clock signals. A controller then adjusts the delay of the clock signals based on the first output of the phase detection circuit and a bit of a delay shift register to synchronize the clock signals within a predefined range. The controller generates a second output if the phase relation between the plurality of clock signals has changed before the adjusting of the delay of the clock signals has occurred. A noise band circuit is configured to receive the second output of the controller and adjust the predefined range in response to the receiving of the second output.

Abstract: There is provided an adjustment circuit which delays a first and a second signal by a desired delay. After the first and the second signal are inputted to the adjustment circuit via a first and a second signal line, respectively, the first and the second signal are exchanged and are inputted via the second and the first signal line, respectively. A detection circuit receives the first and the second signal from the adjustment circuit, and detects the phase differences of these signals, before and after the exchange. The holding circuit holds a first phase difference detected by the detection circuit before the exchange, and holds a second phase difference detected by the detection circuit after the exchange. When the holding circuit holds the first and the second phase difference, a comparison circuit compares these phase differences. A counter counts in accordance with the comparison results of the comparison circuit, and sets the desired delay of the adjustment circuit.

Abstract: The invention is directed to the realization of a .pi./2 phase shifter that provides accurate operation and moreover enables a reduction in current consumption. Such a .pi./2 phase shifter is constructed from a 1/2-frequency divider employing a T flip-flop and includes: a current source circuit which supplies to the T flip-flop a circuit current that determines the output frequency of the T flip-flop and which varies circuit current value according to control signals; and a frequency comparator that compares the output frequency of the T flip-flop and the local signal input frequency, and, based on the comparison results, varies the control signals in a direction such that the output frequency of the T flip-flop matches the local signal input frequency.

Abstract: An input signal and a signal obtained by delaying that input signal are compared, an output signal is produced based on the amount of the delay, and the output signal is used to form a control signal by a low pass filter. The delay of the input signal is controlled so as to produce a plurality of stable clocks and enable stable high speed signal processing without raising the clock frequency.

Abstract: A low-cost microstrip phase detector that is photo-etched onto a circuit board is disclosed. The phase detector is used to detect the phase difference between two high-power radio frequency (RF) signals. One RF signal enters a delay line causing the signal to experience a 180.degree. phase shift. The other RF signal is not phase shifted. Both RF signals are then input into a Wilkinson combiner circuit. The structure of the Wilkinson combiner is such that there is no voltage output from the combiner when the two input signals are exactly 180.degree. out of phase. When the original signals (before the delay line) are in-phase, there is no voltage output from the combiner. However, when the original signals are out-of-phase to begin with, they do not enter the Wilkinson combiner with a 180.degree. phase difference. Instead, the phase difference is greater than or less than 180.degree., depending on whether one input signal leads or lags the other input signal.

Abstract: A dual delay-locked loop is employed to reduce timing skew between two signals, such as localized clock signals, which are both derived from a common input signal. Individually controllable variable delay circuits are used in the signal paths between the common input signal and each of the two signals to nominally create additional delay between the common input signal and each of the two signals. The two signals are compared, the timing skew therebetween is indicated, and the variable delay circuits are each adjusted to reduce the skew between the two signals. The common input signal is not used as a reference signal for the comparison. Rather, the two variably-delayed signals themselves are compared, and both variable delays are adjusted to reduce the skew.

Abstract: A digital delay locked loop (DLL) includes a phase detector for outputting a comparing signal by comparing a system clock signal with a chip clock signal, a shift register for sequentially shifting data bit values in both the directions in accordance with the comparing signal, a phase delay unit for delaying and outputting the system clock signal in accordance with each bit value of the shift register, a domain selecting controller for detecting an overflow or an underflow condition of the shift register and outputting a domain selection controlling signal, and a domain selector for adjusting the phase of a driving signal from one region comprising 0.degree..about.180.degree. and to another area comprising 180.degree..about.360.degree. and carrying out a domain transition whenever an overflow or an underflow condition is generated when the phase reaches a boundary region of the two domains.

Abstract: A system is provided for generating an accurate and stable output clock signal of a desired output frequency in response to a system clock signal having a system clock period. The system uses an accurate and stable reference clock signal. The system comprises a measuring circuit and a ratio counter. The measuring circuit receives and processes the system clock signal and produces a measurement, referred to as the system clock measurement, that is indicative of the system clock period. The ratio counter receives the system clock signal and the system clock measurement and generates the output clock signal. The system is resistant to noise in the output clock signal caused by asynchronicity between the system clock signal and the reference clock signal. The system is resistant because it employs at least one of a lock-on unit and a synchronizing controller in operating the clock measuring circuit.

Abstract: A delay equalization circuit for minimizing the static phase error in a PLL is provided. The delay equalization circuit includes an external clock signal variable delay path, and an element for creating a pulse with a width proportional to the delay of the external clock signal variable delay path. The delay equalization circuit also includes a delay path in the feedback loop, and second element for creating a second pulse in proportion to the delay of the internal delay path. Finally, the circuit contains a comparison device. The comparison device compares the first and second pulses. The comparison device outputs a difference signal in proportion to the difference in the external and internal path delays. That difference signal is fed back and used to control the external path delay such that the external delay is driven to be substantially equal to the internal delay, minimizing the static phase error of the PLL device.

Abstract: A controlled delay path inserts a selected delay into a clock distribution circuit to create a total clock delay that is equal to an integer number of clock cycles relative to a reference dock signal or which produces a selected phase relationship to the reference dock signal. The delay path correction of the invention is particularly useful in circuits having a wide range of possible system clock frequencies or having programmable routing of clock signals, and therefore a wide range of operating delays. A reference clock signal is directed to a range of selectable voltage controlled delay elements by a phase detector that receives the reference clock signal and a feedback signal, and that produces an error voltage which adjusts the voltage controlled delay elements to produce an output clock signal. Additional selectable delays may be included that create offset options and allow selection of a leading, lagging, or in-phase reference dock/output clock relationship.

Abstract: A circuit for synchronizing a periodic ramp signal utilized in a switching mode power converter to system clock signal. A capacitor is charged through a resistor. When a voltage across the capacitor reaches a predetermined level, the capacitor is discharged and the charging cycle is repeated, thereby generating the periodic ramp signal across the capacitor. A waveform shaping circuit shapes the ramp signal into a rectangular wave signal having a same frequency and phase as the ramp signal. A phase comparator compares a phase of the rectangular wave signal to a phase of the system clock signal for forming a phase error signal. The phase error signal controls a level of current supplied to the timing capacitor by a voltage controlled current source. When the frequency of the system clock signal is higher than the frequency of the ramp signal, the phase comparator causes the voltage controlled current source to supply additional current to the capacitor, increasing the frequency of the ramp signal.

Abstract: According to the present invention, when a semiconductor device is tested, a signal for test can be set in the semiconductor device at a desired timing. A second delay circuit of the present invention has the same structure as a first delay circuit in a phase lock loop, and receives a control voltage from the phase lock loop so as to generate a clock signal with a frequency according to the control voltage and to delay and output the clock signal. A second pulse generator generates two-phase clocks by using delayed signals generated by the second delay circuit. Switches are used for switching between a system clock output terminal during an actually active time and a system clock output terminal during testing.

Abstract: A clock generating circuit includes a plurality of delay lines connected in cascade, each delay line including two switching elements for letting in or shutting out a clock, and a delay element connected to each of the switching elements. A PLL circuit and a semiconductor device both include the clock generating circuit. The number K of the delay units in each of the delay lines of the clock generating circuit is calculated from:K>?{1/(2.multidot.N.multidot.F.sub.ref)}-(T.sub.mul)!/(T.sub.

Abstract: The phase of an acquisition clock for a digital oscilloscope is modulated by summing an offset voltage with the output of the phase detector of a delay lock loop. The offset voltage is generated by a digital-to-analog converter which is fed input values by a microprocessor running a number generator routine.

Abstract: Disclosed is a phase detection apparatus for accurately calculating the phase of an input digital complex baseband signal point independently of its amplitude value, without requiring any large-capacity arc-tangent table memory and within a practical calculation time. This phase detection apparatus rotates the phase of the input signal point in a clockwise direction and determines whether the rotated signal point agrees with a reference phase point. If the rotated signal point leads the reference phase point, the signal point is further rotated by an angle onehalf of the predetermined angle. If the rotated signal point lags behind the reference phase point, the signal point before the rotation is rotated by a half angle of the predetermined angle. Rotational angles, 180.degree., 90.degree., 45.degree., . . . , for the individual rotations are stored in a table.

Abstract: A variable delay circuit is provided which automatically compensates for variations in delay time due to manufacturing variables. The construction is such that with variable delay gates (VD) of a reference delay time generation circuit (21), the delay time for one cycle of a designed reference clock signal (CK) is compensated using a phase comparison device (22) and a low pass filter (23). By arranging the reference delay time generation circuit (21) proximately to paths (121-124 and 141-144) which are weighted with the same variable delay gates (VD) as in the reference delay time generation circuit (21), the reference delay time generation circuit (21) and the paths (121-124 and 141-144) are given the same extent of variation. Hence variations in delay time can be compensated for using the same control signal CTR.

Abstract: A digital delay line supplies from a periodic input signal n signals with the same period mutually shifted by one n-th of the input signal period. The digital delay line includes n cells, each of which includes m delay elements in series, each output of a delay element being connected to an input of a multiplexer. The output phase of the n-th cell is compared with that of the input signal phase. The output of a multiplexer of the n cells is modified after each comparison.

Abstract: This is an integrated timing circuit which can be formed on a microprocessor chip. The circuit uses an oscillator having a delay line and a variable delay element. The delay line and the delay element vary together to hold the velocity of signal propagation in the circuit substantially constant. The output, of the oscillator is coupled to one input of a comparator circuit. A series of inverter circuits, each of which has a respective variable delay are connected to the input of the oscillator and to a second input of the comparator circuit such that the comparator circuit senses the difference between the output signal of the inverter series and the output signal of the oscillator circuit to provide an error signal proportional to the sensed difference. A feedback loop is provided, to the variable delay means in said oscillator and to the inverter circuits to correct for the sensed difference, to establish a uniform and stable time standard at the output of the oscillator.

Abstract: A clock signal distribution circuit provides a synchronized clock signal to a plurality of chips implementing an integrated circuit. The clock signal distribution circuit has a first and a second phase lock loop, a series of voltage controlled delay circuits and a pair of transmission lines formed between the chips. The input clock signal is transmitted from the first chip to the second chip through a transmission line, the end of which is a node supplying the output clock signal to the internal circuit of the second chip. The clock signal is then returned from the output node through the second transmission line. The first phase lock loop controls the series of voltage controlled delay circuits such that the signal at a midpoint reference node has a phase equal to the phase of the output clock signal. The second phase lock loop controls the first voltage controlled delay circuit such that the signal at the first output node has a phase synchronized with the phase of the input clock signal.

Abstract: In an internal clock signal generation circuit, a plurality of internal clock signals of different phases are generated based on an external clock signal. The internal clock signals are synchronized with the external clock signal by a PPL circuit. The plurality of internal clock signals are respectively supplied to a plurality of internal circuit blocks. Since the phases of the generated internal clock signals are different the phases of the internal clock signals arriving at the internal circuit blocks can be matched even if delays of the signals between the internal clock signal generation circuit and the plurality of internal circuit blocks are different. Thus, clock skews between the plurality of internal clock signals can be reduced and the phase of the internal clock signal and the phase of the external clock signal can be synchronized.

Abstract: A controlled delay path inserts a selected delay into a clock distribution circuit to create a total clock delay that is equal to an integer number of clock cycles relative to a reference input clock signal or which produces a selected phase relationship to the reference clock signal. The delay path correction of the invention is particularly useful in circuits having a wide range of possible system clock frequencies or having programmable routing of clock signals, and therefore a wide range of operating delays. A reference input clock signal is directed to a range of selectable voltage controlled delay elements by a phase detector that receives the reference input clock signal and a feedback signal, and that produces an error voltage which adjusts the voltage controlled delay elements to produce an output clock signal. Additional selectable delays may be included that create offset options and allow selection of a leading, lagging, or in-phase reference input clock/output clock relationship.

Abstract: A digital delay line supplies from a periodic input signal n signals with the same period mutually shifted by one n-th of the input signal period. The digital delay line includes n cells, each of which includes m delay elements in series, each output of a delay element being connected to an input of a multiplexer. The output phase of the n-th cell is compared with that of the input signal phase. The output of a multiplexer of the n cells is modified after each comparison.

Abstract: A phase synchronization circuit uses a phase comparator and adjustable delay lines that selectively delay a system clock timing signal applied to two integrated circuit chips. The phase comparator and delay lines compensate for propagation delays in each of the integrated circuit chip. The phase comparator receives bus clock signals of the two chips and generates two trigger signals for application to two counters. The counters count signals are applied to corresponding delay lines, which are clocked by a system clock. The delayed timing signals from the delay lines furnish timing signals to the corresponding integrated circuit chips. The count of the counter which corresponds to the integrated circuit chip having the smaller propagation delay is increased until the bus clock signals for the two integrated circuit chips are phase synchronized.

Abstract: A delay locked loop (DLL) is described in which a phase detector compares the phase of the output of the DLL with that of a reference input. The output of the phase comparator drives a differential charge pump which functions to integrate the phase comparator output signal over time. The charge pump output controls a phase shifter with unlimited range that adjusts the phase of the DLL output so that the output of the phase comparator is high 50% of the time on average. Because the DLL adjusts the phase shifter until the output of the phase detector is high 50% of the time, on average, the relationship of the DLL output clock to the input reference clock depends only on the type of phase detector used.

Abstract: A delay locked loop (44) includes an arbiter circuit (86), a VCD circuit (85), and a collapse detector (88). The arbiter circuit (86) receives an input signal and provides a retard signal to adjust the amount of propagation delay of VCD circuit (85), in order to synchronize the phases of the input signal to an output signal of the VCD circuit (85). The collapse detector (88) detects if the output signal of the VCD circuit (85) has failed to change logic states within a predetermined length of time. The delay locked loop (44) can lock the phases of two signals having different frequencies.

Abstract: An integrated digital circuit includes an oscillation circuit comprising basic gate circuits having the number of stages proportional to the number of gates existing in the critical path of a synchronized circuit network and capable of controlling an oscillating frequency by at least one control signal line. A synchronized circuit network constructed with basic gate circuits capable of controlling the delay time by at least one control signal line operates synchronously by an oscillation signal transfer line. A control circuit controls the oscillation circuit and the synchronized circuit network using the control signal line so that the frequency of signal input from an externally input signal line is equalized with the frequency of signal from the oscillation circuit.

Abstract: A system clock signal is delivered to a plurality of load devices by means of a common loop filter and delay line and a plurality of phase detectors and charge pumps each associated to a different load. The delay line provides a plurality of substantially identical phase corrected clock signals, each clock signal being coupled to the associated load device via an associated conductor member. In one embodiment, each conductor member comprises a loop consisting of a pair of conductors having substantially identical path lengths. The phase adjusted clock signals on the proximal end of the outbound conductor are coupled back as a first feedback signal to one input of the associated phase detector. Another feedback signal comprises the clock signal returned from the device node along the second conductor of the pair. A third input to the phase detector is the system input clock signal, which is also coupled to a reference input of the delay line.

Abstract: A circuit, indicating the first or last signal activated among n signals, includes flip-flops respectively associated with pairs of signals, a first signal of each pair being applied to a reset input of a flip-flop and a second signal of each pair being applied to a set input. Logic gates are respectively associated with each considered signal and are connected to indicate whether the considered signal is the first or the last activated signal when the flip-flops associated with all the pairs of signals including the considered signal are at respective suitable states once the first or last signal is activated.

Abstract: To ensure error-free transmission of digital information, very stringent requirements are placed on the accuracy and stability of the clock generators. It is known to use microprocessor-controlled digital phase-locked loops for this purpose, which contain costly high-stability crystal oscillators. An accurate system clock signal is to be provided even if the reference clock signal fails. Contradictory requirements are placed on the phase-locked loops, namely, on the one hand, a wide bandwidth to achieve a small time interval error, and, on the other hand, a narrow bandwidth to minimize the effect of jitter and wander on clock accuracy if the reference clock signal should fail. The invention provides a circuit arrangement for a low-cost clock generator which generates a highly accurate clock frequency even in the event of a failure of the reference clock signal.

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: The present invention relates to a circuit board having a plurality of integrated circuits provided thereon, wherein each integrated circuit (IC) receives a common clocked input reference signal and outputs a dam signal. Each integrated circuit is provided with a de-skewing circuit which compensates for signal delays in the IC so as to synchronize the output data signal with the clocked input reference signal. The de-skewing circuit is operative to generate a simulated signal delay to the input signal which emulates the signal delays of the IC.

Abstract: In a sampling phase controlling apparatus for controlling a phase of a clock signal supplied to a transmission system including a discriminating circuit for discriminating a received signal and an equalizer for removing an intersymbol interference component from the received signal, a first phase control circuit is provided to control the phase of the clock signal in accordance with accumulated intersymbol interference components, and a second phase control circuit is provided to control the phase of the clock signal in accordance with the accumulated intersymbol interference components and a differential value thereof. One of the first and second phase control circuits is selected by a selector circuit.

Abstract: A digital phase shifter for phase-shifting a cyclic input signal includes first--third dividers 1, 4 and 8, first and second phase detectors 2 and 6, first and second voltage controlled oscillators (VCOs) 3 and 7, and a digital comparator 5. The input signal F(IN) and a clock signal F(VCO3) output from the first VCO3 are divided by N and M at the first and second dividers, respectively and phases of the divided signals are compared at the first phase detector 2, whereby the leading edges of the input and clock signals are synchronized. The second divider 4 also generates a count value (m) representing a cycle order number to the comparator, where it is compared with a preset value (.phi.) for determining the amount of phase shift, and an equate pulse EQ5 is generated when the compared values are the same.