Abstract: An improved scan flip-flop and method of using same. The scan flip-flop has a separate dedicated scan output driven by a scan output signal driver. Scan shift race conditions are minimized by providing a weak scan output signal driver and inserting delay elements within a cell for a scan flip-flop in the scan signal path. The use of the improved scan flip-flop allows for a one-pass scan synthesis process which provides accurate flip-flop cell timing and area information during the design process.

Abstract: An integrated circuit is provided with Fully Automated Scan Testing (FAST)-lite flip-flop. The integrated circuit has data, scan in, master-hold, clock, scan-into-master, and master to-scan-out inputs. A first transistor circuit is connected to the data, master-hold, and clock inputs and has a first transistor circuit output. A second transistor circuit is connected to the can in and scan-into-master inputs and has a second transistor circuit output. A first flip-flop is connected to the first transistor circuit and second transistor circuit outputs and has a first flip-flop output. A third transistor circuit is connected to the second transistor circuit output and the master-to-scan-out input and has a third transistor circuit output. A second flip-flop latch is connected to the third transistor circuit output has a second flip-flop output. The FAST-lite flip-flop uses the normal functionality of the first flip-flop and second flip-flop to operate either in a normal mode or a test mode for scan testing.

Abstract: The circuit forms an edge-triggered D-Flip-Flop with a master/slave configuration. The master circuit has only one master switch controlled by a clock signal and followed by a first inverter. The slave circuit has a slave switch followed by a second inverter and a regenerative feedback-loop. The master and slave switches can easily be realized using n-MOS-transistors instead of transmission gates, thus achieving small chip area. The Flip-Flop can easily be amended by set and reset devices and it is suitable for mass applications such as memory and microprocessor chips.

Abstract: A circuit for writing data to configuration memories is utilized to write initial value data to the configuration memories, thereby initializing the same. In addition, a transistor for providing disconnection between a writing data signal and an output signal of a configuration memory is inserted so that no collision occurs between both signals during the writing of data to the configuration memory.

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 dual-edge pulse-triggered flip-flop comprising a gated data latch and a gated scan latch coupled in series with the data latch. In normal operation, the data latch captures a data input D in response to clock pulses ckp generated on each edge of a system clock ck. During an input scan operation, a selected stimulation bit presented on a scan input SI is transferred first into the scan latch in response to a scan input clock ak, and then into the data latch in response to a scan output clock bk. This stimulation bit is simultaneously presented on a scan output SO. During an output scan operation, a data bit Q presented on the scan input SI is transferred first into the scan latch in response to the scan input clock ak, and then into the data latch in response to the scan output clock bk. This data bit is simultaneously presented on the scan output SO.

Abstract: A toggle flip-flop circuit that increases operational speed and decreases power consumption with a simplified configuration. The toggle flip-flop circuit has a master latch circuit, which includes an emitter-coupled logic (ECL) circuit, and a slave latch circuit, which includes an ECL circuit. The master slave circuit and the slave latch circuit are driven by the same ECL drive circuit.

Abstract: A low power, high performance flip-flop which does not require a full feedback path in the master stage includes a master stage driven by a data input, and an inverter. A slave stage includes a pass device for isolating the slave stage and the master stage, the slave stage having a feedback path for holding a data value passed to the slave stage.

Abstract: Techniques for providing improved memory flip-flops and other logic circuits are described. A flip-flop uses only one p-channel transistor to drive the output node strongly to achieve fast results. To reduce diffusion area, parallel logic is substantially eliminated and only series branches are used, in critical areas. This allows all pull-up transistors and/or all pull-down transistors to be formed from contiguous active areas. The D-to-Q path is reduced, and the clock is used to control the output. The clock becomes the dominant controller of the output when it is located closest to the output. Placing the clock devices closest to the clocked nodes reduces clock skew. The rising D response time and falling D response time are caused to be as close as possible to reduce the overall cycle time. To reduce parasitics in the circuit, complex-gates are used which are asymmetric. Even multiples of series branches per gate are used to share contacts and eliminate breaks in the layout diffusion.

Abstract: A D-type master-slave flip-flop includes a master unit receiving an input variable and producing two first intermediate variables, a transfer unit including at least two logic gates and a clock connection connected to one input of each of the gates, which are adapted to supply two second intermediate variables as a function of the input variable and the clock signal and are looped to the master unit, and a slave unit to form at least one output variable. Another input of a first gate of the transfer unit is connected to the master unit to receive directly the true value of one of the variables supplied by the master unit. Another input of the second gate of the transfer unit is connected to the master unit to receive therefrom the complement of the same variable. The second intermediate variables are independent of each other. The flip-flop has the advantage that it is insensitive to the slopes of the flanks of the clock signals.

Abstract: It is an object of the present invention to provide a sequential circuit having nonvolatile characteristics capable of holding data therein even when the power supply is shut-off. An inverter circuit INV1 is formed by replacing a pair of transistors consisting the conventional CMOS inverters with transistors NT and PT both having an MFMIS structure. A polarization state corresponding to an ON state is held in a ferroelectric layer 32 of the transistor NT even when the power supply thereof is shut off, and another polarization state corresponding to an OFF state is held in a ferroelectric layer 32 of the transistor PT. The transistors NT and PT are turned into ON and OFF state respectively according to the polarization states held in their ferroelectric layers 32 when the power supply is turned ON again. In this way, the inverter circuit INV1 recovers its state to the state right before the shut-off by turning the power supply into the ON state again.

Abstract: A slave latch circuit has a gate for being supplied with a signal which is an inversion of a signal outputted from a first output terminal and a control signal, generating a signal based on the supplied signals, and outputting the generated signal from a second output terminal. The gate controls the output signal outputted from the second output terminal. The gate may comprise a NAND gate for being supplied with a ground potential as the control signal in a normal mode of operation for thereby fixing the output signal outputted from the second output terminal to a power supply potential. Alternatively, the gate may comprise a NOR gate for being supplied with the power supply potential as the control signal in the normal mode of operation for thereby fixing the output signal outputted from the second output terminal to a ground potential.

Abstract: A data storage circuit (50) has a data input (12′) for receiving a data voltage (D″) and a node (44) for receiving an interim voltage in response to the data voltage. The data storage circuit also includes an output enable circuit (34) for providing at least one conditional path coupled to the node and for coupling the interim voltage to the node. The output enable circuit has a transistor (40p) having a first threshold voltage and operable to provide a conductive path along the at least one conditional path. The data retention circuit (46 and 48) has at least one transistor having a second threshold voltage higher in magnitude than the first threshold voltage. The data storage circuit includes a second node (58) for receiving a second interim voltage in response to the first interim voltage. A second output enable circuit (52) provides at least one conditional path for coupling the second interim voltage to the second node.

Abstract: This invention reduces power in flip flop apparatuses by providing flip flop apparatuses that have fewer clock trees than prior art flip flops yet still support some or all of the Level Sensitive Scan Design (LSSD) functionality. In preferred embodiments of the present invention, one clock tree is used instead of two to provide lower power, and less switching devices in clocks splitters are used, which also provides lower power. Additionally, a flushable single clock splitter is provided that allows one clock tree to be used up to the flushable single clock splitter and provides two clocks on the output of the flushable single clock splitter. This saves some power yet still allows for dual clock flip flop designs.

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: 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: The purpose of this invention is to ensure an active use of the inverse short-channel effect in the ratio circuit and to guarantee stable operation at low power source voltage. In this ratio circuit, N-channel MOS transistor 12 of CMOS circuit 10 on one side forms the drive element, while P-channel MOS transistor 18 of CMOS circuit 16 on the other side forms the load element. Said N-channel MOS transistor 12 on the drive side and P-channel MOS transistor 16 on the load side have their drain terminals electrically connected to each other through transfer gate 22 made of N-channel MOS transistor. MOS transistor 12 on the drive side has a single channel CHa with the inverse short-channel effect. MOS transistor 18 on the load side has plural, e.g., two, channels CHb1 and CHb2, connected in tandem, each of which displays the inverse short-channel effect.

Abstract: A D-FF circuit for operating a master flip-flop and a slave flip-flop at each predetermined timing in accordance with a plurality of clock signals generated by a clock signal generating circuit, wherein the clock signal generating circuit generates the plurality of clock signals at different timings, the slave flip-flop starts operating in accordance with a clock signal which is generated at an earlier timing than another clock signal generated by the clock signal generating circuit, and the master flip-flop stops operating in accordance with a clock signal which is generated at a later timing than another clock signal generated by the clock signal generating circuit.

Abstract: A gated scan flop circuit and methods of making the gated scan flop circuit are provided. In one example, the scan flop circuit includes a sub-scan flop circuit that incorporates a multiplexer and a flip flop circuit, and a data terminal D that is connected to the sub-scan flop circuit. Also provided is a first logic gate that is configured to receive a scan input terminal SI and a clock gate terminal G. The first logic gate has a first logic gate output that is connected to the sub-scan flop circuit. A scan enable terminal SE is connected to the sub-scan flip circuit, and a latch circuit is configured to receive the clock gate terminal G, and track its input while the clock terminal CLK is inactive. A second logic gate having a second logic gate output is provided that is configured to receive as inputs the scan enable terminal SE and the latched clock gate terminal G. A third logic gate is configured to receive a clock terminal CLK and the second logic gate output.

Abstract: A flip-flop having a sleep mode in which power consumption is reduced. The flip-flop comprises a clock input, a data input, an input stage, an input gate, an output stage and an output clamp. The input gate is interposed between the data input and the input stage and operates in the sleep mode to isolate the input stage from the data input. The output stage is coupled to the input stage and includes an output having a first output state and a second output state. The output clamp operates in the sleep mode to set the output stage to a predetermined state regardless of the data states at the data input and the clock input. The predetermined state is the one of the output states in which the leakage power consumption of the flip-flop is less than in the other of the output states. The predetermined state may alternatively be the one of the output states in which the leakage power consumption of circuitry connected to the output of the flip-flop is less than in the other of the output states.

Abstract: A logic circuit includes a combinational circuit 11 and a sequential circuit, outputs D0 to D3 of the combinational circuit 11 are provided to the respective data inputs D of flip-flops 12 to 15 of the sequential circuit through respective multiplexers 22 to 25, and the flip-flops 12 to 15 are cascaded through the multiplexers 22 to 25 to construct a scan path. AND gates 32 to 35 are provided for preventing changes in outputs of the flip-flops 12 to 15 from being transmitted to the combinational circuit 11 when the scan mode signal *SM is active, whereby the combinational circuit 11 is kept inoperative when data is serially transferred on the scan path consisting of the D flip-flops 12 to 15, an inverter 30 and the multiplexers 22 to 25.

Abstract: An improved master-slave flip-flop that is characterized by a novel clock generator. The improved flip-flop preserves the true master-slave relationship by ensuring a two step latching process is executed by non-overlapping clocks. The clock generator features an inverter in combination with a current limiter. The current limiter has the effect of shifting the trip point of the inverter such that non-overlapping clocks may be derived from a single master clock signal or a master clock signal and its complement.

Abstract: A master-slave flip-flop circuiting having transistors connected in cascade in two stages between a power supply and ground. A clock differential amplifier, a master flip-flop, a slave flip-flop, and a waveform-shaping amplifier are all connected mutually in parallel to a power supply. High-speed operation at a minimum operation power supply voltage is achieved.

Abstract: A controllable latch/register circuit for an integrated circuit comprises an input latch (30) coupled in series with an output latch (32). The latches are operated under control of a control circuit (34) having mode inputs. In one mode, the latches are operated as a non-transparent register; the output latch (32) holds the output stable while new data is inputted to the input latch (30); the output latch (32) is only opened once the input latch has been latched closed. In one or more other modes, the latches are operated as a single controllable transparent latch; for example, one or the latches (30) can be held permanently open such that operation of the circuit depends entirely on the state of the other latch (32).

Abstract: A data latch circuit of the present invention, which corresponds to the semiconductor circuit, is provided with a master flip-flop and a slave flip-flop. The master flip-flop fetches a first signal in response to a first clock signal, holds first data corresponding to the first signal as binary data in response to the first clock signal, and also outputs the first data as a second signal. The slave flip-flop fetches the second signal in response to an OR-gated result obtained between the first clock signal and either one or a plurality of second clock signals, and the slave flip-flop holds second data corresponding to the second signal in response to the OR-gated result, and also the slave flip-flop outputs a third signal corresponding to the second data.

Abstract: According to one embodiment, a master-slave flip-flip circuit (MS-FF) (100) includes master input transfer gate (108) connected to the input of a master latch portion (102) and a slave input transfer gate (110) connected to the input of a slave latch portion (104). A clock generating circuit (112) includes a first inverter (114-0) that provides an inverted clock signal CB1 and a second inverter (114-1) that provides a non-inverted clock signal C1. The clock signals C1 and CB1 are provided to the slave input transfer gate (104). The clock signals C1 and CB1 are further provided to the master input transfer gate (108) through clock lines (116-0) and (116-1) which have a parasitic resistances R1 and R2. The parasitic resistances R1 and R2 delay the C1 and CB1 signals and thereby provides a delayed inverted clock signal CB2 and a delayed non-inverted clock signal C2 to the master input transfer gate (108).

Abstract: A flip-flop circuit comprising a dynamic master coupled to a clock, the clock being characterized by an active stated of a limited duration, and a static latch coupled to the clock and coupled to the dynamic master. In an embodiment, the limited duration is less than the minimum time period in which the master can change from a first state to a second state.

Abstract: A latch circuit includes a first circuit including an N-MOS transistor having a first electrode receiving a signal, a second electrode outputting the signal, a gate electrode, and a P-well, and a first inverter including input and output terminals. The second electrode of the N-MOS transistor is electrically connected to the input terminal of the first inverter, and the gate electrode of the N-MOS transistor is electrically connected to the P-well of the N-MOS transistor.

Abstract: A method of detecting two bits of data transmitted with a single clock edge includes the step of assessing the value of a first data bit and a second data bit transmitted with a single clock edge to generate a first output bit indicative of the value of said first data bit. The assessing step may be implemented by integrating the first data bit and the second data bit, or by identifying signal transitions between the first data bit and the second data bit. The second output bit is produced by simply passing the second data bit.

Abstract: There is provided a D-type flip-flop circuit which is improved in terms of operating frequency. First and second current supplying circuits are provided as sources for supplying currents to first and third differential circuits for inputting data and to second and fourth differential circuits for holding data in a master circuit and a slave circuit. Further, timing for supplying the currents to the respective differential circuits for inputting and holding data are controlled by first and second clock signals, respectively. The D-type flip-flop circuit is improved in terms of operating frequency by optimizing timing for writing input data and timing for holding data by arranging the first clock signal so as to have a certain delay with respect to the second clock signal. Further, the D-type flip-flop circuit is improved with respect to the operating frequency also by optimizing the value of the currents supplied to the respective differential circuits.

Abstract: A flip-flop circuit 10 is provided with a discord detecting circuit DDC and a clock control circuit CCC. The discord detecting circuit DDC detects the discord of a data input signal DIS of the flip-flop circuit 10 with a data output signal DOS thereof. When the data input signal DIS discords with the data output signal DOS, the clock control circuit CCC supplies a short pulse to the flip-flop circuit 10 as an internal clock signal ICLK in synchronism with the rising of an external clock signal ECLK. On the other hand, when the data input signal DIS coincides with the data output signal DOS, the clock control circuit CCC supplies a low level signal to the flip-flop circuit 10 as the internal clock signal ICLK. Thus, it is possible to suppress electric power consumption required to supply a clock signal, and to prevent errors from being caused in a flip-flop operation.

Abstract: A flip-flop having one or more stages (e.g., a master stage and a slave stage in a master-slave flip-flop, or a single stage as in a latch), at least one stage having a driver coupled at its input and output to a feedback path with a gated inverter having embedded preset and/or clear logic. By embedding the preset/clear logic in the feedback path, the driver can be implemented using a simple inverter. Moreover, the preset and/or clear functionality can be added without adversely affecting either the setup time or the clock-to-Q propagation time of the flip-flop.

Abstract: Techniques for providing improved memory flip-flops and other logic circuits are described. A flip-flop uses only one p-channel transistor to drive the output node strongly to achieve fast results. To reduce diffusion area, parallel logic is substantially eliminated and only series branches are used, in critical areas. This allows all pull-up transistors and/or all pull-down transistors to be formed from contiguous active areas. The D-to-Q path is reduced, and the clock is used to control the output. The clock becomes the dominant controller of the output when it is located closest to the output. Placing the clock devices closest to the clocked nodes reduces clock skew. The rising D response time and falling D response time are caused to be as close as possible to reduce the overall cycle time. To reduce parasitics in the circuit, complex-gates are used which are asymmetric. Even multiples of series branches per gate are used to share contacts and eliminate breaks in the layout diffusion.

Abstract: A D flip-flop circuit operating in master-slave configuration which has low power consumption and is capable of high-speed operation, and a method for lowering power consumption in such a circuit is provided. The circuit embodiment includes two latches, each with a switching and memory section, and two interlaced current sources. In response to the active high clock signal the master latch memory section uses the current from the first current source while the slave latch switching section uses the current from the second current source, and vice versa. The switching section of each latch is biased with a higher current than the memory section, to provide the circuit with low power consumption. The output current provided to the switching section is preferably substantially twice the magnitude of the current provided to the memory section. The ratio of the currents of the current sources for the switching and memory section is preferably in the range of about 30% to 70%, depending on the clock frequency.

Abstract: A circuit configuration for storing data has a first clocked register structure connected in parallel with a second register structure. The second register structure is operated in a push-pull mode relative to the first register structure. As a result, changes in the state of an input signal at the input are stored for each clock phase of a clock signal. Therefore, the clocking of the input signal of the circuit configuration can be done at the clock rate of the clock signal.

Abstract: A master-slave flip-flop and method is provided for use with critical path circuits, for example, driving output pads on an integrated circuit. Briefly described, in architecture, the master-slave flip-flop comprises a master stage and a slave stage. The master stage includes a pass gate, an input inverter coupled to the pass gate, a feedback inverter coupled across the input inverter, and a driving inverter coupled to the output of the input inverter. The output of the driving inverter is coupled to the slave stage which includes a second pass gate through which the output of the driving inverter is applied to the master-slave flip-flop output. The above architecture results in a fast setup time and a fast clock-to-Q time without the problems associated with kickback. Also, the output of the master-slave flip-flop is tristatable.

Abstract: A scan flip-flop circuit includes first and second master latches, a slave latch, and first, second, and third switches. The first master latch latches a data input signal and outputs it to the first output terminal in normal operation. The second master latch latches a scan input signal and outputs it to the second output terminal in a scan test. The slave latch latches an output from the first master latch that is input to a first input terminal, thereby outputting it to a third output terminal in normal operation, and latches an output from the second master latch that is input to a second input terminal, thereby outputting it to the third output terminal in a scan test. The first switch disconnects the first output terminal of the first master latch from the first input terminal of the slave latch in a scan test. The second switch disconnects the first output terminal of the second master latch from the second input terminal of the slave latch in normal operation.

Abstract: An improved flip-flop is disclosed. The flip-flop (12) includes a latch circuit (22) that receives an input signal and a clock signal. The latch circuit (22) generates an output signal that tracks the input signal during a first portion of the clock signal, and remains constant during a second portion of the clock signal. A master flip-flop (36) receives the clock signal and the output signal of the latch circuit, and generates an output signal that tracks the output signal of the latch circuit (22) during the second portion of the clock signal, and remains constant during the first portion of the clock signal. A slave flip-flop (48) receives the clock signal and the output signal of the master flip-flop and generates an output signal. The output signal tracks the output signal of the master flip-flop (36) during the first portion of the clock signal and remains constant during the second portion of the clock signal. The flip-flop may be incorporated into a shift register (10).

Abstract: A gate-array cell uses smaller and larger transistors. Four larger transistors are provided: two n-channel and two p-channel. A small p-channel transistor is placed between the contact tabs of the polysilicon lines of the two larger p-channel transistors, and between the p-channel transistors and a N-well tap. A small n-channel transistor is similarly placed between the contact tabs of polysilicon lines of the two larger n-channel transistors, and between the n-channel transistors and a P-well tap. The cell is slightly expanded in height to accommodate the two smaller transistors. The smaller transistors enable a reduction in the number of transistors required for latches and flip-flops. The smaller transistors allow a feedback inverter to directly connect to an input, since the input can easily over-power the feedback current. This is not possible for standard gate array cells having only one transistor size. Transmission gates are eliminated when direct feedback is feasible.

Abstract: A differential flip-flop having reduced circuit complexity, clock loading, and power consumption. The circuit is particularly well adapted for systems requiring high-speed differential flip-flops. The proposed flip-flop uses the parasitic capacitors associated with circuit nodes to dynamically store information. The differential flip-flop uses only one current source, as opposed to the two typically required by its conventional counterpart, saving fifty percent of the total power requirement. This power saving is a tremendous advantage at high frequencies, since current must be high to ensure high-speed operation of the transistors in the circuit. Furthermore, the new flip-flop presents a significantly reduced (fifty percent) load to the clock driver, thus further enhancing the power performance of the systems in which it is used.

Abstract: A latched receiver circuit capable of receiving data and clock simultaneously. New data is latched at every clock cycle without delay or buffering of the data or the clock. The latched receiver may also receive and latch small signals without the aid of a receiver preamp or added delay.

Abstract: The present invention includes a circuit assembly and method of synchronizing plural circuits. According to one aspect of the present invention, a circuit includes: an oscillator configured to generate a reference clock signal; a first circuit including: a first divider configured to generate a first internal clock signal responsive to the reference clock signal; and reset generation circuitry configured to receive an external reset signal and generate a reset second circuit signal synchronized with a predefined position of the first divider, with the reference clock signal and with the external reset signal; and a second circuit including: reset detection circuitry configured to generate a reset detection signal synchronized with the reset second circuit signal and the reference clock signal; and a second divider configured to set to a predefined position responsive to the reception of the reset detection signal and generate a second internal clock signal synchronized with the first internal clock signal.

Abstract: Disclosed is a low power scan flop cell design for enabling low power scan mode testing and reduced heat dissipation. The low power scan flop therefore enables "at speed" testing in scan mode, which enables comprehensive testing of high speed timing faults. The scan flop cell embodies a scan cell that has inputs that include a data input pin, a scan input (SI) pin, a scan enable (SE) input, and a clock input. The scan cell has outputs that include a Q' output and an NQ' output. The scan flop cell further includes a first logic gate having a Q output, a first input pin that is connected to the Q' output of the scan cell, and a second input pin. The scan flop also includes a second logic gate having an NQ output, a first input pin that is connected to the NQ' output of the scan cell, and a second input pin. An electrical interconnection is formed between the scan enable input of the scan cell and the second input pin of both the first logic gate and the second logic gate.

Abstract: A integrated circuit, such as a memory integrated circuit, includes a vernier clock adjustment circuit receiving an input clock signal and providing a rising-edge clock signal representing the input clock signal delayed by a rising-edge delay and providing a falling-edge clock signal representing the input clock signal delayed by a falling-edge delay. An edge triggered circuit receives data and the rising-edge and falling-edge clock signals, and stores data at the rising-edge of the rising-edge clock signal and at the falling-edge of the falling-edge clock signal. One form of the invention is a memory system having a memory controller coupled to memory modules through data and command busses. Each memory module includes the vernier clock adjustment circuitry.

Abstract: A combined D-type latch and D-type flip-flop circuit where the latch setup-and-hold time is independent of the clock state. This is accomplished in one method by rerouting the data path to the Master to provide equivalent delays to both the Master and the Slave. In a second method, a clocking circuit provides on-board clocking where the data ia always latched first into the Slave, and after a fixed delay, the data are latched into the Master.

Abstract: A master slave type flip-flop circuit having a master latch circuit ML and a slave latch circuit SL has a voltage level converter circuit 20 in the slave latch circuit SL to reduce the number of elements used in the circuit, which results in reducing the power consumption and in increasing the operation speed of the circuit.

Abstract: There is disclosed a frequency divider that operates at an improved operating speed and provides frequency division given with a frequency division ratio of N, where N is an odd number. The frequency divider comprises first, second, and third stages of D-type flip-flops. The first stage selects either the output from the second stage or the output from the third stage according to the logic level of the output from the third stage. Delay is eliminated from between the first and third stages and from between the first and second stages. Consequently, the operating frequency can be enhanced.

Abstract: An apparatus has a clock monitoring device, which determines whether or not the clock rate of an input clock signal (.PHI..sub.0) has fallen below a predetermined minimum clock rate. A system is provided which, from the input clock signal, forms a master clock signal (.PHI..sub.m) and a slave clock signal (.PHI..sub.s) which are in a form such that both the switches (S1) of dynamic master registers (ML) and the switches (S2) of dynamic slave registers (SL) are closed provided that the clock rate has fallen below the minimum clock rate. Otherwise, at most either the switches (S1) of the dynamic master latches (ML) or the switches (S2) of the dynamic slave latches (SL) are closed. The primary advantage achieved hereby is that in the event of failure of the input clock signal, in particular in circuits with a high degree of pipelining, undefined register states do not result in an impermissibly high current consumption.

Abstract: A flip-flop circuit consists of a conventional pulse-drive flip-flop plus a clock driver and a local pulse generator that generates a pulse signal according to the output of the clock driver. The flip-flop circuits of this kind are used to form, for example, a shift register in which the clock drivers are connected in series from the last stage toward the first stage. The clock driver in the last stage receives a clock signal, which is successively supplied to the flip-flop circuits from the one in the last stage toward the one in the first stage. This arrangement prevents a data-pass-through problem, assures a sharp waveform of pulse signals, and reduces the size of each clock driver. This type of flip-flop circuits may be used to form logic circuits such as N-bit registers and N-bit shift registers.

Abstract: A semiconductor integrated circuit includes a first shift register composed of a plurality of first flipflops each including a first selector for selecting a first or second clock, a second selector for selecting an inverted signal of the first clock or a third clock, a third selector for selecting a first data signal or a first scanning signal, a first latch circuit for latching an output of the third selector, and a second latch circuit for latching an output of the first latch circuit. The semiconductor integrated circuit further includes a second shift register composed of a plurality of second flipflops each including a fourth selector for selecting a second data signal or a second scanning signal, a third latch circuit for latching an output of the fourth selector, and a fourth latch circuit for latching an output signal of the third latch circuit.