Abstract: A frequency correction circuit includes a temperature sensor (100) disposed to measure temperature and produce temperature signals representing sensed temperatures. A data supplier (110) stores information items, receives digital input signals representing and produces a digital output information signal representing an item selected in accordance with the digital input signal. A control circuit (120) receives the temperature signals and receives the digital output information signal. The control circuit (120) produces control signals based on the temperature signals. A clock circuit (150) is disposed to generate a reference frequency signal. A digital synthesizer (130) receives the reference frequency signal and the control signals. The digital synthesizer produces an output frequency signal as directed by the control signals received from the control circuit (120).

Abstract: There is provided a semiconductor integrated circuit including a clock buffer capable of suppressing the increase of its chip size and decreasing its electric power consumption even if the capacity increases or even if the functional operations are varied.

Abstract: A circuit comprising an oscillator, a reference path, and a feedback path. The oscillator may have a reference input receiving a reference signal, a feedback input receiving a feedback signal, and an output. The reference path may provide the reference signal from a reference clock input. The feedback path may provide the feedback signal from the oscillator loop output. At least one of the reference path and the feedback path comprises a programmable delay circuit.

Abstract: An integrated circuit has a plurality of signal paths, at least one of which has a delay cell. The delay cell has an input terminal for receiving an signal from the signal path, and a plurality of delay paths for generating a corresponding plurality of delayed signals delayed by different delays from the input signal. At least one of the delay paths employs two different-delay subpaths coupled in parallel to provide a delayed signal delayed by an interpolated delay. A multiplexer (MUX) of the delay cell provides one of the delayed signals as an output signal to the signal path based on a control input signal applied to the multiplexer.

Abstract: A pulse generator of a type that includes at least one current mirror connected between first and second voltage references and to at least one initiation terminal receiving a pulsive-type initiating signal, connected to a load terminal receiving a load signal, and connected to an output terminal providing an output signal.

Abstract: A clock generator circuit includes an oscillation circuit which generates a first clock signal, a first timer which counts the first clock signal, a ring oscillator which generates a second clock signal, a second timer which counts the second clock signal, and a third timer that generates a third clock signal which is the output clock signal.

Abstract: An apparatus and method for synchronizing sampling of a video signal to a video synchronization signal of the video signal are provided. The frequency-divided output of an oscillator (or other controllable frequency source) is applied as one input to a phase detector, while the other input to the phase detector is supplied by the video synchronizing signals. The error signal voltage output of the phase detector is applied to correct the frequency, and thereby the phase, of the oscillator output through a dynamically-tuned phase-locked loop filter until the phases of the two input signals are in perfect agreement and no error voltage is produced. After a delay for this phase correction, during which time all video amplification is suspended, an output of the oscillator is then applied to sample the image without the presence of phase disparities while video amplification is restored. Full dynamic range digital acquisition then proceeds with extremely high accuracy at any desired resolution.

Abstract: A clock signal switching circuit that switches between two clock signals having a phase difference. The clock signal switching circuit includes a first selector that selects one of the clock signals according to the level of a selection signal, a second selector that selects one of first and second control signals according to the level of the selection signal. The level of the first and second control signals are changed in response to an original signal and the first or the second clock signal. A gate circuit generates the output signal from the first and second selectors wherein the level of the selection signal is changed in response to the original signal after the levels of both of the first and second control signals have changed.

Abstract: A duty cycle regulator derives from an input clock of arbitrary duty cycle an output clock having an adjustable duty cycle of similar frequency. The duty cycle regulator includes a bistable circuit for receiving an input clock pulse and providing the output clock, coupled through a feedback loop to an adjustable delay unit having a delay interval equal to an adjustable fraction of the input clock period. When an input clock pulse is received, the bistable circuit is set giving high signal to the delay unit, which after the delay interval resets the bistable circuit to give a low signal. The delay unit includes two charge pumps alternately feeding and draining electric charges into and from a low-pass filter. The delay interval can be adjusted to a desired duty cycle independent of the input clock frequency, by setting the ratio of electric currents through the two charge pumps.

Abstract: A clock synchronizer circuit provides an internal clock signal for an integrated circuit that is synchronized to an external system clock signal, such that the internal clock integrated is aligned with and has minimal skew from the external system clock signal. The clock synchronizer circuit allows synchronizing of internal clocks of an integrated circuit with the external system clock having a period &tgr;ck less than the cumulative delay of internal receiving and distribution circuits of the integrated circuit.

Abstract: A clock gater circuit which may be easily tuned for the purpose of adjusting the deadtime between non-overlapping clock signals. The clock gater circuit has first and second clock inputs, a clock output, a falling clock edge generation circuit, and a rising clock edge generation circuit. The falling clock edge generation circuit is coupled between the first clock input and the clock output, and the rising clock edge generation circuit is coupled between the second clock input and the clock output. Each clock edge generation circuit has a feed-forward path and a feedback path. The feed-forward path of one of the clock edge generation circuits includes an inverter chain having an even number of inverters. If the inverter chain appears in the rising clock edge generation circuit, the inverter chain provides for easy adjustment of the rising edge of a clock produced by the gater circuit.

Abstract: An apparatus comprising a clock for providing a clock signal, means for providing a delayed version of the clock signal, two transparent latches having clock inputs controlled by opposite polarities of the delayed clock signal, a multiplexer having (i) inputs fed by outputs of the latches, and (ii) a select input fed by the clock signal, and means for providing a select signal for selecting the latch whose clock is inactive. Preferably, each of the latches has a scan input gate and a scan output gate, and the scan output of the first latch is applied to the scan input of the second latch to form a scannable latch pair. Also, preferably, the apparatus further comprises a data port for applying data to the first and second latches, and an exclusive OR gate at the data port, whereby the apparatus produces a gated clock signal. Also disclosed is a method of operating this apparatus.

Abstract: The present invention discloses an input buffer which can improve the properties of a setup time and a hold time of an input signal. When the setup time is important, a path of a short delay time is employed, and when the hold time is important, a path of a long delay time is used. Therefore, the internal setup time/hold time may be suitably selected in the system application conditions. For this, the input buffer includes: a buffer for receiving a signal through an input pin; a plurality of delay units for delaying the signal inputted from the buffer by a different delay time; and a selecting unit for selectively outputting one of the output signals from the plurality of delay units according to an externally-inputted reference signal and the logic variation of the input signal from the buffer.

Abstract: A clock circuit, in accordance with the present invention, includes a first circuit stage for providing a first output signal and a second output signal. The first circuit stage includes inputs for clock signals. A switch is coupled to the first stage for switching an output polarity by selecting one of the first output signal and the second output signal generated by the first circuit stage in accordance with a control signal. A second circuit stage is coupled to the first circuit stage through the switch. The second circuit stage for shaping the first and second output signals input thereto from the switch. The second circuit stage includes an output for outputting clock pulses based on the first and second output signals. The control signal is generated from the clock pulses.

Abstract: A clock control method is proposed, in which malfunctions caused by clock skews are decreased when the same high-speed clock is used inside and outside an IC. An original clock is input via CKIN, with the return path of an output buffer connected to an input buffer in an input/output buffer. The clock, once output via the output buffer, returns to the IC as a reentry clock. The selected reentry clock or original clock are used in the IC. The clock appearing at SYSCK is used in an external circuit. By using the reentry clock in the IC, the clock skew corresponding to the delay of the output buffer can be decreased.

Abstract: A Duty cycle optimized prescaler (10) optimizes the clock duty cycle as close as possible to fifty percent. This is achieved by employing two count by two counters (11,12), one (12)to count negative edges of the clock pulse, and one (11)to count positive edges of the clock pulse. Each counter (11,12) output is connected to a comparator (14,15) which compares each counter output (11,12)to a prescaler setting (13). The comparators (14,15) outputs are input to an OR gate (16), the output of which, when, a logic 1, resets the counters(11,12) and toggles a flip-flop circuit (17) providing a clock output signal.

Abstract: There is disclosed an electronic circuit comprising a clock driver for generating a clock signal, a clock line on which the clock signal generated by said clock driver is transmitted, a shield-cum-signal line extending along said clock line serving optionally for transmission of a predetermined signal and for shielding of a noise generated from said clock line in accordance with a mode, a transfer gate for transferring a transmitted signal to said shield-cum-signal line, said transfer gate turning on or off in accordance with a mode, and a transistor disposed between said shield-cum-signal line and a power source, said transistor turning on when said transfer gate turns off and turning off when said transfer gate turns on in accordance with a mode.

Abstract: A method of switching a clock signal is provided, which switches the frequency of a clock signal while keeping the state of an internal subsystem just before a switching operation in a short period of time and at the same time, power consumption is finely adjustable. First, supply of a clock signal having a first frequency to an internal subsystem is stopped according to a clock-change instruction. Then, the first frequency of the clock signal is switched to a second frequency different from the first frequency while supply of the clock signal having the first frequency is stopped. Finally, supply of the clock signal having the second frequency is started to the internal subsystem. The supply of the clock signal to the internal subsystem may be stopped almost simultaneously with the clock-change instruction or stopped with a specific time delay with respect to the clock-change instruction.

Abstract: A frequency correction circuit includes a temperature sensor (100) disposed to measure temperature and produce temperature signals representing sensed temperatures. A data supplier (110) stores information items, receives digital input signals representing and produces a digital output information signal representing an item selected in accordance with the digital input signal. A control circuit (120) receives the temperature signals and receives the digital output information signal. The control circuit (120) produces control signals based on the temperature signals. A clock circuit (150) is disposed to generate a reference frequency signal. A digital synthesizer (130) receives the reference frequency signal and the control signals. The digital synthesizer produces an output frequency signal as directed by the control signals received from the control circuit (120).

Abstract: The internal clock signal generating circuit of the present invention includes a pulse generation circuit for receiving a reference clock signal which is generated in response to an external clock signal, and generating an internal clock signal. The pulse generation circuit includes a pulse generation unit for generating a pulse signal which is activated in response to a rising edge of a first delay signal obtained by delaying the reference clock signal by a first delay time, and deactivated in response to a falling edge of a second delay signal obtained by delaying the reference clock signal by a second delay time which is shorter than the first delay time, and a driving unit for generating the internal clock signal which is activated in response to a falling edge of the reference clock signal and deactivated in response to a rising edge of the pulse signal.

Abstract: A clock stretching circuit (110) mites between a synchronous bus (112) and a microcontroller (124) which is asleep most of the time to save electrical power. The bus is of a type in which a slow bus device can cause the sender of data to “hold” the data until the slow device is up to speed. The stretching circuit (110) is of small component count and low power consumption, and there is no requirement for a continuous clock. In one embodiment is comprised of a triple analog switch (120, 121, 122) and a very small number of additional components. In another embodiment a dual four-position multiplexer (162, 163) is employed. In still another embodiment, four transistors (210, 212, 213, 215) are used with handful of additional components. A level shifter (220, 221, 222, 223) including an MOSFET and a large-value resistor help to minimize power drain within the bus device.

Abstract: There is disclosed a pulse generating circuit which comprises an oscillator circuit 1 receiving an input clock signal, a P-channel MOS transistor 2 having a gate connected to an output of the oscillator circuit 1, a delay circuit 4 having an input connected to an output line 10, an oscillator circuit 5 having an input connected to an output of the delay circuit 4, an N-channel MOS transistor 3 having a gate connected to an output of the oscillator circuit 5, an inverter 6 having an input connected to the output of the oscillator circuit 1, a delay circuit 7 having an input connected to the output line 10, an AND circuit 8 receiving an output of the inverter 6 and an output of the delay circuit 7, and an N-channel MOS transistor 9 having a gate connected to an output of the AND circuit.

Abstract: An activation signal generating circuit includes a combinational logic circuit and a switch. The combinational logic circuit receives a normal mode control signal and a test mode control signal, and the switch receives a periodic clock signal. The switch is controlled by the output of the combinational logic circuit such that an activation signal is generated from the periodic clock signal. In one preferred embodiment, the switch is a CMOS change-over switch having two complementary MOS transistors connected in parallel, and a potential setting circuit imposes a specified potential at the output of the switch when the switch is open. A method of generating an activation signal is also disclosed.

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: A method and apparatus for drastically reducing timing uncertainties in clocked digital circuits simply, at virtually no cost, and using only standard clock drivers and simple, inexpensive electrical components is described. The method includes the steps of minimizing timing uncertainties by controlling both clock skew and clock jitter. Intrinsic clock skew is eliminated by ganging the outputs of a multi-line clock together onto a capacitive metal island disposed on a printed circuit board (PCB). Extrinsic clock skew is controlled through the use of wide, relatively high-capacitance traces of matched length and disposed on a single, common signal layer of the PCB, each leading to a respective receiver circuit and terminated identically. Clock jitter is controlled by electrically isolating a region of the PCB, disposing the clock driver in the region in such a way as to minimize noise, and providing quiet local power and ground to the region.

Abstract: A variable width pulse generator. The pulse generator includes a pulse circuit responsive to a reset signal to provide a pulse circuit signal. A variable delay reset loop path, coupled to the pulse circuit, is responsive to the pulse circuit signal to provide the reset signal. A control signal may vary the width of a pulse generated by the circuit by varying the length of a delay associated with the reset loop path. Both a coarse control signal, such as a signal that selectively removes a logic element in the reset loop path, and a fine control signal, such as a signal that controls a tunable delay element in the reset loop path, may be used to adjust the pulse width.

Abstract: A clock control circuit includes a forward pulse delay circuit including a plurality of delay circuits for delaying a forward pulse signal FCL, a backward pulse delay circuit including a plurality of delay circuits for delaying a backward pulse signal RCL, a state-hold section including a plurality of state-hold circuits for controlling the operation of the backward pulse delay circuit in accordance with the transmission condition of the forward pulse signal in the forward pulse delay circuit, and an input stop circuit for stopping inputting a pulse corresponding to an external clock signal to the backward pulse delay circuit during a predetermined period from the time point when the external clock signal begins to be supplied.

Abstract: ON-OFF operations of the pull-up and pull-down transistors are independently controlled so as to generate a start edge of a pulse signal in synchronizing with any one of a rising edge and a falling edge of a first cycle of the clock signal, and then generate an end edge of the pulse signal in synchronizing with any one of a rising edge and a falling edge of a later cycle than the first cycle, thereby avoiding concurrent ON-states of the pull-up and pull-down transistors, whereby the pulse generator is capable of generating the pulse signal completely depending upon a clock signal externally supplied but being independent from internal factors of the circuits thereby allowing a high speed and constant width pulse generation.

Abstract: A semiconductor integrated circuit having a core region and an I/O region includes a clock signal line for transferring a clock signal, basic unit cells and pull-up unit cells. The basic unit cells are arranged in rows and columns within the core region. Each of the basic unit cells has a PMOS active region and an NMOS active region. The pull-up unit cells are arranged at predetermined intervals between the basic unit cells. The pull-up unit cells are coupled to the signal line for pulling up an electric level of the clock signal line in response to the clock signal.

Abstract: A high gain, low input capacitance clock buffer includes a plurality of transistors configured to supply an inverted representation of an input reference signal by alternatively switching to provide the output. While either of the transistors is operating to switch the input clock signal, the other transistor is in a stable state. Furthermore, by using n-type FET's, significant power reduction and space savings may be achieved.

Abstract: A first clock and a second clock are provided. The first and second clocks operate at first and second frequencies, respectively. The phase difference between the first clock and the second clock is accumulated to generate a control signal. In response to the control signal, the phase of the second clock is controlled so as to synchronize with the first clock. Preferably, the phase of the second clock is shifted from the normal timing, when the accumulated value reaches a cycle of the first clock.

Abstract: A clock circuit includes a clock signal generator for generating a first clock signal during a normal mode of operation and an oscillating dual clock generating circuit for producing a second clock signal during a second mode of operation. The oscillating dual clock generating circuit is connected to the output of the clock signal generator. In the first mode of operation, the clock signal from the clock signal generator is passed through the oscillating dual clock generating circuit to a control device. In a second mode of operation, the input of the oscillating research signal is isolated. Isolation of the oscillating dual clock generating circuit causes oscillation in the dual clock generating circuit. Thus, the dual clock generating circuit acts as an oscillator during the second mode of operation to generate a second clock signal.

Abstract: The invention relates to a wave form shaping circuit, which outputs signals after shaping the input signal to a duty 50% wave form regardless of whether or not input signals are of duty 50%, wherein a duty determination circuit is provided, which determines and instructs the timing position of duty 50% of clock signals to be outputted, upon receiving a timing signal prepared by a timing generation circuit 2.

Abstract: A slave clock generation system and method suitable for use with synchronous telecommunications networks generates one or more slave clocks from a selected reference clock using a direct digital synthesis technique. A multiplexer selects a reference clock from a number of available sources, each of which can be at its own spot frequency, based on a predetermined selection order. Toggle detectors monitor each of the available clock sources, and block the selection of any that are not within a specified frequency range. A local oscillator establishes short-term and long-term measurement periods; the cycles of the selected reference clock are counted over consecutive short-term measurement periods to determine the relative frequency of the selected clock with respect to the frequency of the local oscillator. The cycle counts are fed to a phase-to-clock converter, which produces a slave clock output having a frequency that varies with the relative frequency measured for the selected clock.

Abstract: A clock buffer circuit includes an amplifier section and a control section. The amplifier section amplifies a clock signal in response to a control signal. The control section generates the control signal based on an amplitude of the clock signal.

Abstract: A pulse generating circuit for a dynamic random access memory includes a fixed pulse generating unit receiving an input signal and generating an output pulse signal of a fixed width, a pulse delay unit receiving the input signal and delaying an output pulse signal of a variable width, a pulse width detecting unit receiving the input signal and an inverted input signa, outputting a first flag signal displaying a low pulse width by detecting the low pulse width of the input signal, and outputting a second flag signal displaying a high pulse width by detecting the high pulse width of the input signal, a NOR gate performing a logical operation on the first flag signal and the second flag signal and outputting a third flag signal, and a multiplexer coupled to the fixed pulse generating unit, the pulse delay unit, and the pulse width detecting unit and outputting an output pulse signal in accordance with the third flag signal.

Abstract: A segmented dual delay-locked-loop (DLL) has a coarse DLL and a fine DLL. Each DLL has a series of buffers, a phase detector, charge pump, and bias-voltage generator. The bias voltage controls the delay through the buffers. The bias voltage of the coarse DLL is adjusted by the phase comparator to lock the total delay through the buffers to be equal the input-clock period. The coarse DLL divides an input clock into M equal intervals of the input-clock period and generates M intermediate clocks having M different phases. An intermediate mux selects one of the M intermediate clocks in response to a phase-selecting address. The selected intermediate clock K and a next-following intermediate clock K+1 are both selected and applied to the fine DLL. The K clock is input to a series of N buffers in the fine DLL while the K+1 clock is directly input to a phase detector. The phase detector compares the K+1 clock to the K clock after the delay through the buffers.

Abstract: The invention relates to a wave form shaping circuit, etc. which outputs signals after shaping the input signal to a duty 50% wave form regardless of whether or not input signals are of duty 50%, wherein a duty determination circuit is provided, which determines and instructs the timing position of duty 50% of clock signals to be outputted, upon receiving a timing signal prepared by a timing generation circuit 2.

Abstract: The present invention is directed to a method and apparatus for producing a square wave output signal with a clock circuit that possesses characteristics of low current consumption, relatively tight duty cycle control, and versatility over a wide range of voltages and input signal frequencies down to, and including DC. Exemplary embodiments receive an input signal, and process the input signal into an output square wave signal. A processing of the input signal is achieved using at least one current mirror for controlling a duty cycle of the output square wave signal said at least one current mirror being implemented in part with at least one pair of cascoded transistors. The processing is further achieved with an output stage having at least one inverter operatively connected with a node between the transistors of the at least one pair of cascoded transistors to control switching of the at least one pair of cascoded transistors.

Abstract: A negatively delayed signal generating circuit for compensating a duty rate of an input signal, wherein the negatively delayed signal has a larger frequency than that of the input signal and a stable duty rate regardless of the duty rate of the input signal, thereby being stably applicable to a memory device requiring a high speed operation.

Abstract: A clock generating circuit synchronizes an internal clock signal with an external clock signal, and has a delay circuit implemented by a series of delay stages connected through pairs of signal transfer lines to one another; each of the delay stages has a series combination of a first charging circuit and a first discharging circuit connected between a positive power line and a ground line and a series combination of a second charging circuit and a second discharging circuit connected in parallel to the first series combination, and each pair of signal transfer lines is connected between the first series combination of one of the delay stage and the second series combination of the next delay series; a potential edge signal is propagated through charging/discharging operations toward a certain delay stage during a first time period equal to the pulse period of the external clock signal, and returns to the first delay stage so as to generate a one-shot pulse in the next pulse period; even if the pulse period f

Abstract: A semiconductor device includes a variable-delay circuit which delays an input-clock signal to generate a delay clock signal, a clock-control circuit which selects one of the input-clock signal and the delayed clock signal, an output circuit which outputs data in synchronism with a clock signal selected by the clock-control circuit, and a DLL circuit which adjusts a delay of the variable-delay circuit. The DLL circuit includes a delay-control circuit which adjusts the delay of the variable-delay circuit, and a clock-selection circuit which controls the clock-control circuit to select one of the input-clock signal and the delayed clock signal. The variable-delay circuit is controlled such that the delay is not increased when the input-clock signal is selected by the clock-selection circuit.

Abstract: A variable clock divider circuit is provided. The variable clock divider circuit receives an input clock signal and generates an output clock signal having an output clock frequency that is less than the input clock frequency of the input clock signal. In one embodiment, a controller generates a rising-edge control signal and a falling-edge control signal. An output generator drives rising edges on the output clock signal in response to active edges on the rising-edge control signal. Conversely, the output generator drives falling edges on the output clock signal in response to active edges on the falling-edge control signal. The frequency of the rising-edge control signal and the frequency of the falling-edge control signal are variable. Common settings for the frequency of the rising-edge control signal and the falling-edge control signal include the frequency of the input clock signal divided by an integer.

Abstract: In integrated circuits, to modify the operation of the charge pumps or voltage step-up circuits, they are sent a variable frequency signal at the input with the aim of breaking the regularity of the pulse train that enters the charge pump. This limits the risks of entry into resonance and limits radiation at a given frequency. The variable frequency signal is typically produced by a logic circuit and by a main oscillator whose transmission of certain pulses is masked by the combined action of different masking signals. The duty cycle ratios of the masking signals are less than that of the signal from the main oscillator. Such duty cycle ratios are preferably produced following the passage of a signal to a lower frequency than that of the signal of the main oscillator in a circuit for the detection of high transitions.

Abstract: An apparatus having an input node and an output node for generating a timing signal. The apparatus includes an enabling circuit, one or more inverters, and one or more capacitive elements. The enabling circuit generates a signal of a first state when one or both of the input node and the output node are of a second state, and generates a signal of the second state when both of the input node and the output node are of the first state. The first state and the second state represent two opposite logic states. The inverters generate opposite state outputs in responsive with their inputs. The inverters are connected in series with a first inverter being responsive to the enabling circuit and a last inverter for generating a signal for the output node. The capacitive elements are connected between a voltage source and one of the inputs of the inverters.

Abstract: A method and apparatus for drastically reducing timing uncertainties in clocked digital circuits simply, at virtually no cost, and using only standard clock drivers and simple, inexpensive electrical components is described. The method includes the steps of minimizing timing uncertainties by controlling both clock skew and clock jitter. Intrinsic clock skew is eliminated by ganging the outputs of a multi-line clock together onto a capacitive metal island disposed on a printed circuit board (PCB). Extrinsic clock skew is controlled through the use of wide, relatively high-capacitance traces of matched length and disposed on a single, common signal layer of the PCB, each leading to a respective receiver circuit and terminated identically. Clock jitter is controlled by electrically isolating a region of the PCB, disposing the clock driver in the region in such a way as to minimize noise, and providing quiet local power and ground to the region.

Abstract: A clock signal control apparatus for a data output buffer that controls a data access time and an output signal maintaining time of the data output buffer based on a period of an input first clock signal. The apparatus includes a clock signal generator for generating a second clock signal having a period controlled by a period of a first clock signal, a clock signal controller and a data output buffer. The clock signal controller delays the second clock signal from the clock signal generator for a predetermined time, generates an output enable signal and a third clock signal in accordance with the second clock signal. A data output buffer receives a data signal, buffers the data signal in accordance with the third clock signal and the output enable signal from the clock signal controller, and generates an output data signal. The second clock signal has one of a plurality of periods based on the first clock signal.

Abstract: The present invention provides a novel clock frequency divider that accepts an input clock having an input clock frequency and provides an output clock with an effective clock frequency of one of 1/N, 2/N, . . . , (N-1)/N, N/N times the input clock frequency, where N is an integer. The clock frequency divider of the present invention divides the input clock frequency asymmetrically by filtering out one or more of each N pulses on the input clock, as dictated by select signals. For example, in a clock frequency divider having N=8, a first clock output signal filters out one of each eight pulses, retaining seven pulses. Therefore, the effective frequency of the output clock signal is (N-1)/N, or 7/8, times the frequency of input clock signal. Similarly, a second output clock signal retains six of every eight pulses, a third retains five, and so forth.

Abstract: A variable frequency dividing circuit adjusts the frequency dividing ratio by a non integer. The variable frequency dividing circuit includes a sequence storing part for storing an N-bit sequence data to output the N bits of the sequence data in parallel. The variable frequency dividing circuit also includes a sequence generator for receiving the N-bit sequence data from the sequence storing pan to generate a sequence control signal and a sequence control signal converter for converting the sequence control signal according to a frequency variation request to generate the converted sequence control signal. The variable frequency dividing circuit further includes a frequency divider for dividing a clock signal frequency according to the converted sequence control signal outputted from the sequence control signal converter and a clock signal generator for producing a clock waveform in accordance with the divided clock signal frequency.

Abstract: A clock waveform synthesizer that will create a timing signal that is a multiple of the frequency of an master clock is disclosed and has the capability to programmably adjust the rising edges and falling edges of the synthesized waveform within the period of the master clocks. The clock waveform synthesizer has a multi-tapped delay line. The multi-tapped delay line will create replications of the master clock that are incrementally delayed from the master clock to create a plurality of delay signals. A fraction of the plurality of delay signals will be the inputs to each of a plurality of multiplexers. A select port on each of the multiplexers will receive a select signal to choose one delay signal of the fraction of the plurality of delay signals. The one selected delay signals will be the input to the set terminals and reset terminals of a plurality of edge-triggered set/reset flip-flops.