Abstract: A clock output pad and a return clock receiving pad are disposed on a logic chip at a portion near a side of an integrated circuit chip and a portion near another side of the integrated circuit chip that opposes to the side. A clock receiving pad is disposed on a memory chip at portion near the side and the other side respectively. The clock receiving pad is electrically connected to the clock output pad and the return clock receiving pad. A plurality of clock signals are supplied from the logic chip to the memory chip, and a plurality of return clock signals are returned from the memory chip to the logic chip.

Abstract: In a programmable logic device having high-speed serial interface channels, a clock distribution network for providing one or more high-speed clocks to dynamic phase alignment circuitry of those high-speed serial interfaces includes at least one bus that is segmentable (e.g. using tristatable buffers). This allows the bus to be divided into different portions that can be connected to different clock sources when the high-speed serial interfaces are running at different speeds. In one embodiment, the segmenting elements (e.g., the aforementioned buffers) are located between selected channels (e.g., every fourth channel), limiting the size of the different segments. In another embodiment, segmenting elements are located between each channel, allowing complete user freedom in selecting the sizes of the segments. Thus, instead of providing a bus for every clock source, multiple clocks can be made available to different channels by segmenting a single bus.

Abstract: In one embodiment, a method for balancing clock signals in a clock tree includes, at a register, receiving a divided input clock signal and a non-divided input clock signal and generating a first output clock signal based on the received divided input clock signal and the received non-divided input clock signal, the first output signal being associated with a first delay. The method further includes, at a delay line, receiving the non-divided input signal, delaying the non-divided input signal for a time substantially equivalent to the first delay, and generating a second output clock signal associated with a second delay substantially equal to the first delay.

Abstract: Integrated circuit serializer circuitry is provided that converts parallel data to serial data on an integrated circuit. A two-phase global serializer master clock generator uses a four-phase internal clock to generate a two-phase global serializer master clock. The two-phase global serializer master clock is distributed globally on the integrated circuit using a distribution path. The integrated circuit has multiple serial communications channels each of which has an associated serializer. Each serializer contains circuitry that derives a number of clock signals from the two phases of the global serializer master clock. Each serializer uses the derived clocks in converting parallel data to serial data for transmission over its associated serial communications channel. The serializers each contain two smaller serializers that convert first and second sets of parallel data to first and second serial outputs. A 2:1 serializer in each serializer merges the first and second serial outputs.

Abstract: Signal transmission circuitry on an integrated circuit ameliorates the effects of possible inequality in rise and fall times of buffer circuits along the transmission circuitry by providing at least one of the buffer circuits as an inverting buffer circuit and at least one other of the buffer circuits as a non-inverting buffer circuit. The invention may be of particular interest for use in clock signal distribution networks on integrated circuits such as programmable logic devices.

Abstract: A clock distribution network having: a main trunk configured to provide a differential clock signal; a plurality of branches coupled to the main trunk for distributing the differential clock signal to a plurality of circuit elements on the integrated circuit; and a plurality of switches coupling the main trunk to the plurality of branches.

Abstract: Methods and Apparatuses for generating and distributing a clock signal between components within a semiconductor chip. According to one embodiment of the invention, a clock generator, distributed over an integrated circuit, includes a plurality of cells each coupled to multiple adjacent ones of the plurality of cells by different clock wires; wherein, for each of the plurality of clock wires, the cell on one end generates the rising edge and the cell on the other end generates the falling edge. According to another embodiment of the invention, an integrated circuit includes a distributed clock generator and a plurality of sets of synchronous logic. The distributed clock generator includes a plurality of cells and a plurality of clock wires. The plurality of clock wires each couple together two of said plurality of cells such that said plurality of cells are coupled together in grid.

Abstract: A data processing system (100) comprises a system bus (120), a plurality of devices (110, 150, 160, 170) coupled to the system bus (120), a bus monitor circuit (140), and a clock generator (130). The plurality of devices (110, 150, 160, 170) includes at least one bus master (110, 150) which is capable of performing accesses on the system bus (120). The bus monitor circuit (140) is coupled to the at least one bus master (110, 150), and has an output for providing a bus idle signal to indicate that no bus master is attempting to perform an access on the system bus (120). The clock generator (130) has an output coupled to at least one of the plurality of devices (110, 150, 160, 170) and provides a bus clock signal having a first frequency when the bus idle signal is inactive and having a second frequency lower than the first frequency when the bus idle signal is active.

Abstract: In a programmable logic device having high-speed serial interface channels, a clock distribution network for providing one or more high-speed clocks to dynamic phase alignment circuitry of those high-speed serial interfaces includes at least one bus that is segmentable (e.g. using tristatable buffers). This allows the bus to be divided into different portions that can be connected to different clock sources when the high-speed serial interfaces are running at different speeds. In one embodiment, the segmenting elements (e.g., the aforementioned buffers) are located between selected channels (e.g., every fourth channel), limiting the size of the different segments. In another embodiment, segmenting elements are located between each channel, allowing complete user freedom in selecting the sizes of the segments. Thus, instead of providing a bus for every clock source, multiple clocks can be made available to different channels by segmenting a single bus.

Abstract: The performance of digital signals depends to a great extent on the frequency. However, the higher the frequency, the shorter the remaining time, in which digital signals can be reliably received by a receiver from a driver via a printed conductor. The run time of the clock pulse and signals must be optimized in such a way that no timing losses occur at any location, even in the extreme environmental conditions. The invention improves the timing and minimizes external influences by coupling the output signals to an internal PLL clock pulse.

Abstract: Output switch noise resulting from simultaneous switching is reduced by time multiplexing the output switching operation. A plurality of phase-shifted clock signals are generated such that each of the phase-shifted clock signals exhibits an active (e.g., rising) edge during a single period of the reference clock signal. Different groups of input/output blocks are switched in response to the various phase-shifted clock signals, such that output switching occurs at various times during the period of the reference clock signal. The phase-shifted clock signals can be generated with predetermined phase differences or with dynamically determined phase differences.

Abstract: The number of pulses of a clock signal CLK-A is circularly counted in a count range from “0” to “7”, and count signals indicating count values are produced. A clock signal CLK-B having a frequency lower than that of the clock signal CLK-A is produced from count signals of “3” and “7”, and data transfer between a high speed operating block operated in synchronization with the clock signal CLK-A and a low speed operating block operated in synchronization with the clock signal CLK-B is performed in synchronization with the clock signal CLK-B to receive input serial data or transmit output serial data. When a stuff bit of universal Serial Bus is detected in the input serial data or is inserted in the output serial data, a cycle of the clock signal CLK-B is lengthened by one cycle of the clock signal CLK-A.

Abstract: The burden of developing a complex bridge block imposed on the IP reuser is reduced by introducing a system clock into the IP. The IP composed of a functional circuit of this invention and its synchronizing circuit takes in the system clock by integrating the synchronizing circuit taking in the system clock with the IP functional circuit into the IP in reusing the IP complying with the standard in the development of an LSI with a built-in IP and its derivatives. This enables the reuser to incorporate the IP into the LSI via a simple bridge block, taking into account only the system clock for driving the system bus, which reduces the burden of handling the IP and increases the reusability of the IP.

Abstract: An input buffer circuit is made up from: a differential amplifier that receives an input signal from the outside and a reference voltage for determining the level of the input signal; a transistor for a first operating current path for supplying a prescribed first operating current to the differential amplifier and that, by having a prescribed fixed voltage supplied to its gate, is always ON; and at least one transistor for a second operating current path for supplying a second operating current that is greater than the first operating current to the differential amplifier when ON, the transistor for the second operating current path being ON/OFF controlled in accordance with a control signal from the outside.

Abstract: A real time clock counter includes a serially connected plurality of register units, each register unit having a bit register for storing clock data, a half adder for incrementing the clock data stored in the bit register, and an activation circuit for activating the bit register. Each activation circuit includes a first input for receiving an oscillating timing signal and a second input for receiving a binary carry term from the previous bit register unit's half adder. Each activation circuit also includes an output for outputting a first activation signal or a second activation signal according to the first value and the oscillating timing signal such that when the activation circuit outputs the first activation signal, the bit register is activated, and when the activation circuit outputs the second activation signal, the bit register is not activated, saving power.

Abstract: An apparatus and method for regenerating reset and clock signals and a high-speed digital system using the apparatus and method are provided. In the regenerating circuit of the invention, a clock circuit receives an external clock signal and generates there from an internal clock signal, which is forwarded to a plurality of clocked circuits such as, for example, D flip-flops. A reset circuit receives an external reset signal and generates therefrom an internal reset signal, which is forwarded to the clocked circuits to reset the clock circuits. A clock masking circuit masks the internal clock signal for a masking period such that the clocked circuits are not clocked during the masking period. The high-speed digital system of the invention includes a plurality of function blocks coupled on a bus. The reset and clock regenerating circuit of the invention generates internal reset and clock signals from externally applied reset and clock signals.

Abstract: A device for controlling a clock signal phase to reduce the clock skew includes a clock signal generator, a pad circuit and a phase adjustment device. The clock signal generator is disposed in a chip for generating the clock signal. The pad circuit is disposed in the chip, and electrically connected between the clock signal generator and an external circuit, and includes an output buffer and an input buffer, wherein the output buffer transmits the clock signal to both the external circuit and the input buffer, and the input buffer further transmits the clock signal to a logic circuit module of the chip. The phase adjustment device is disposed in the chip and electrically connected between an output end of the input buffer and the logic circuit module of the chip for adjusting the clock signal required for the operation of the logic circuit module.

Abstract: A semiconductor device includes a transmission line bounded by a first buffer and a second buffer. The first and second buffers are placed such that the transmission line has a length between a minimum and a maximum, thereby permitting narrow clock signal pulses to be transmitted with reduced distortion.

Abstract: A semiconductor integrated circuit includes a plurality of functional blocks, each of which starts and stops an operation thereof in response to assertion and negation, respectively, of a corresponding command signal, a clock generation circuit which generates a clock signal, a clock control circuit which starts supplying the clock signal to each of the functional blocks in response to the assertion of the corresponding command signal, and stops supplying the clock signal to each of the functional blocks in response to the negation of the corresponding command signal.

Abstract: A phase alignment technique includes providing a clock signal to a first clock distribution spine and providing at least one additional clock distribution spine. One PLL (Phase Locked Loop) is provided for each additional clock distribution spine, each PLL having an REF input and an FBK input and an output. The REF input of each PLL is connected to the first clock distribution spine and the FBK input of each PLL is connected to its respective clock distribution spine and the output of each PLL is connected to its respective clock distribution spine to provide a clock signal thereto. Each PLL provides phase alignment between the clock signal on the first clock distribution spine and the clock signal outputted by the PLL to its respective clock distribution spine. The first clock distribution spine and each additional clock distribution spine and its respective PLL may be disposed on an integrated circuit die.

Abstract: A circuit and method for stopping a clock tree while maintaining PLL lock. A clock circuit includes a locked loop circuit and a clock tree distribution network. The locked loop circuit receives an input clock signal and generates a PLL output clock depending upon a feedback signal. The clock tree is coupled to the locked loop circuit and conveys the PLL output clock to a plurality of clocked circuit elements. The clock circuit further includes a gating circuit and a feedback delay circuit. The gating circuit is coupled between the locked loop circuit the clock tree distribution network and selectively inhibits the PLL output clock from clocking the clock tree distribution network. The feedback delay circuit provides the feedback signal, which represents a delayed version of the PLL output clock, during operation including when the gating circuit inhibits the PLL output clock from clocking the clock tree.

Abstract: A system which simplifies the clock tuning process for a clock buffer tree. Essentially, a clock buffer tree is provided where the clock buffer tree includes clock buffers of different strengths. The different strength clock buffers which are in the clock buffer tree have the same pin-out configuration. Hence, it is easy and straightforward to upsize or downsize any of the clock buffers in the clock buffer tree, and it is guaranteed that the new cell will fit into the old cell's slot in the tree. Since none of the nets need to be modified, consistent timing results are achieved. Moreover, the new timing for the modified clock buffer can be anticipated because its wire loading does not change at all. The ease of clock tuning makes it much easier to design clock buffer trees and layouts, and allows the overall design to be completed faster and easier.

Abstract: An apparatus comprising an output connected to a plurality of inputs through a tree of connections. Each of one or more branches of the tree may be equidistant between the output and each of the plurality of inputs.

Abstract: One clock is selected from a plurality of clocks by a selector through programming. Clock lines are connected to the outputs of clock buffers connected to the selector. Programmable connector elements are connected onto these lines, and flip-flops and regulation loads are connected thereto. The programmable connector elements are selected through programming. This construction can realize a clock distributing circuit in a programmable logic device, which can suppress an increase in skew and can reduce a clock line wiring area.

Abstract: A hierarchical clock distribution system includes a global clock grid that distributes a clock signal to a plurality of regional clock grids. Each of the regional clock grids then distributes the signal to a plurality of corresponding loads. The regional clock grids utilize salphasic clocking techniques to distribute the clock signal to the corresponding loads. The global grid achieves low skew based on the periodicity of the clock signal, rather than the dominance of a standing wave. The electrical distance to termination within the regional clock grids is preferably kept low to avoid the occurrence of phase change regions on the regional grids. In one approach, the regional grids are each driven at multiple points in a symmetrical fashion to reduce the electrical distance to termination.

Abstract: A ladder type clock network for reducing the skew of clock signals is provided. The clock network includes a buffer for buffering a clock signal, first delay units for delaying the output of the first buffer by a set time, second buffers connected to respective outputs of the first delay units, and second delay units connected to respective outputs of the second buffers. The first delay units and the second delay units consist essentially of the resistance and capacitance of lines through which the clock signal propagates. Accordingly, the skew of the internal clock signals is reduced, and internal clock signals having a stable duty with respect to variations in a semiconductor device manufacturing process, temperature, and power supply voltage, are generated.

Abstract: A programmable logic device is provided with phase-locked loop (“PLL”) or delay-locked loop (“DLL”) circuitry in which the feedback loop circuitry substantially parallels and duplicates a portion of the clock signal distribution network on the device that receives the main PLL/DLL output signal. In this way the distributed feedback loop circuit more readily provides a substantially exact match for the distributed delay experienced by the signal propagating through the clock signal distribution network that the PLL/DLL circuitry serves.

Abstract: In the present invention a signal generator is described for use in measuring the effects of wire to wire coupling in integrated circuits. A signal is connected to a wire that is surrounded by reference wires. A set of latches are used to set up and initiate signals simultaneously on the reference wires and the signal wire. Using latch reset and preset in phase and out of phase signals are created on the reference and signal wires that are routed in parallel. Several stages can be concatenated together in series to produce a delay resulting from coupling that can be easily measure. The latches at the beginning of each stage are activated by an enable signal to keep the signals in the reference wires and the signal wire synchronized.

Abstract: In this clock control circuit, clock signal CLK from a receiver is supplied to a pulse generating circuit, and the pulse generating circuit generates forward pulse, which is clock signal CLK delayed as much time as A, and pulse s which is synchronized with dock signal CLK and has a pulse width of A. Consequently, as forward pulse becomes “H” while pulse s is “L” without generating pulse which width is narrower than A, the edge part of forward pulse is securely propagated by a forward-pulse delay line even if it is high frequency. Propagation of forward pulse stops at rising edge of pulse s, and rearward pulse is generated in a corresponding stage. This rearward pulse is propagated by a rearward-pulse delay line, and outputted from an output buffer.

Abstract: Fractional cycle stealing units are introduced in the routing of a programmable device such as an FPGA or FPSC to increase system performance resulting from the particular clock routing. The disclosed fractional cycle stealing units enable given amounts of clock skew between individual distribution sinks, and/or between logic paths that are in series. Each of the delay elements ‘steals’ a portion of a clock cycle (and perhaps one or more full clock cycles) from subsequent circuits to provide a more reliable logical function, and to avoid the need for overall additional clock cycles. These fractional cycle stealing elements offer a signal skew adjustment at the sinks of the distribution with no additional routing congestion expense. The disclosed cycle stealing delay elements are programmable, and enable clock skew between individual distribution sinks.

Abstract: The burden of developing a complex bridge block imposed on the IP reuser is reduced by introducing a system clock into the IP. The IP composed of a functional circuit of this invention and its synchronizing circuit takes in the system clock by integrating the synchronizing circuit taking in the system clock with the IP functional circuit into the IP in reusing the IP complying with the standard in the development of an LSI with a built-in IP and its derivatives. This enables the reuser to incorporate the IP into the LSI via a simple bridge block, taking into account only the system clock for driving the system bus, which reduces the burden of handling the IP and increases the reusability of the IP.

Abstract: A programmable logic device is provided with phase-locked loop (“PLL”) or delay-locked loop (“DLL”) circuitry in which the feedback loop circuitry substantially parallels and duplicates a portion of the clock signal distribution network on the device that receives the main PLL/DLL output signal. In this way the distributed feedback loop circuit more readily provides a substantially exact match for the distributed delay experienced by the signal propagating through the clock signal distribution network that the PLL/DLL circuitry serves.

Abstract: A 2/N mode clock generator that generates bus clock signals through the use of bus clock enable signals selecting bus clock pulses that are in phase and out of phase with a core clock signal. The clock generator maintains synchronization between the bus clock signal and the core clock signal so that they are always in a predetermined phase relationship.

Abstract: A programmable logic device is provided with phase-locked loop (“PLL”) or delay-locked loop (“DLL” ) circuitry in which the feedback loop circuitry substantially parallels and duplicates a portion of the clock signal distribution network on the device that receives the main PLL/DLL output signal. In this way the distributed feedback loop circuit more readily provides a substantially exact match for the distributed delay experienced by the signal propagating through the clock signal distribution network that the PLL/DLL circuitry serves.

Abstract: A method for synchronizing multiple subsystems using one voltage-controlled oscillator. The method includes transmitting a phase and frequency aligned output of a voltage-controlled oscillator to each subsystem within a digital system. A first subsystem of the multiple subsystems generates a first internal clock and outputs a synchronization signal to each of the other subsystems. The synchronization signal has a marker that defines a known point in time of the first internal clock. The other subsystems sample the synchronization signal using the output signal of the voltage controller oscillator to determine a starting indicator that indicates the known point in time of the first internal clock. Upon detection of the marker in the synchronization signal, the other subsystems starts a second internal clock that is synchronized with the first internal clock.

Abstract: A programmable logic device is provided with phase-locked loop (“PLL”) or delay-locked loop (“DLL”) circuitry in which the feedback loop circuitry substantially parallels and duplicates a portion of the clock signal distribution network on the device that receives the main PLL/DLL output signal. In this way the distributed feedback loop circuit more readily provides aL substantially exact match for the distributed delay experienced by the signal propagating through the clock signal distribution network that the PLL/DLL circuitry serves.

Abstract: A semiconductor integrated circuit is provided which has an internal core area in which a first set of transistors are regularly arranged, and a peripheral area in which a second set of transistors are arranged to constitute input/output circuits. In this semiconductor integrated circuit, the transistors arranged in the peripheral area include a plurality of transistors that are not used to constitute the input/output circuits, and these unused transistors constitute at least one driver for driving at least one of circuits constituted by the transistors arranged in the internal core area.

Abstract: A clock system produces a high-speed clock signal based on a low-speed clock signal inputted from the outside through the use of a frequency amplifier therein in order to thereby reduce power consumption at a clock buffer. In order to perform the above process, the clock system is composed of an external clock source for producing a clock signal having a frequency of f, a plurality of Rambus DRAMs and a controller, which are synchronized by the clock signal derived from the external clock source. By using the clock system, it is possible to reduce power consumption at the clock buffer and to decrease occurrence of a high frequency noise at a clock pin, and thus, a high qualified system design is also accomplished.

Abstract: A computer system with a semi-differential bus-signaling scheme is described. The computer system includes a transmitter coupled to a common bus. The transmitter sends clock signals and a data signal to logic-comparing devices within a receiver. The logic-comparing devices compare the data signal to a reference voltage while comparing the clock signals to each other. After the comparison, the clock signals can be used to capture the data into a retiming circuit.

Abstract: A clock supplying circuit that supplies a clock to a plurality of controlled circuits 451-454 arranged in respectively different positions. A forward and backward wiring 41, 42 and an internal clock supply wiring 43 are arranged along controlled circuits. A main clock drive circuit 40 is for outputting a first clock to the forward wiring 41 and is for outputting a second shorter phase than the first clock to the internal clock supply wiring 43. A plurality of local clock drive circuits 441-444 arranged close to the controlled circuits, are supplied with a forward clock propagated along the forward wiring and with a back clock propagated along the backward wiring, and are also supplied with the second clock, for delaying the phase of the supplied second clock so as to coincide with a phase intermediate the forward clock and the back clock, and for supplying the delayed clock of the second clock to the respectively corresponding controlled circuits as local clock.

Abstract: A wordline activation delay monitor circuit is disclosed herein which includes a sample wordline located within a data-storing array of a memory, wherein the sample wordline is selected or activated by circuitry having substantially the same structure or location within the memory as circuitry which selects or activates wordlines of the data-storing array. A circuit is disclosed which determines a wordline activation delay for a first subarray group within the memory by activating a sample wordline which is located within a data-storing array of a second subarray group. Corresponding methods are also disclosed.

Abstract: A system for distributing clock signals to multiple locations on a chip with minimal skew is disclosed. A series of FIFO control structures, connected in a ring by signal lines of substantially equal length, generates multiple clock signals of equal phase and frequency. The oscillation frequency of the FIFO control ring may be increased to accommodate higher-speed chips, while maintaining synchronization of clock pulses at each stage of the FIFO control ring.

Abstract: A gated clock tree synthesis (CTS) method is provided for the purpose of synthesizing a gate array logic circuit to allow optimal topological arrangement of the gate array on the logic circuit. This in turn allows the logic circuit to operate more efficiently. The logic circuit includes at least one clock generator, a plurality of control gates each having one input end connected to a control signal and the other input end connected to receive the output clock signal from the clock generator, a plurality of first logic elements that are directly driven by the output clock signal from the clock generator, and a plurality of second logic elements that are driven by the gated clock signal outputted from each of the control gates under control by the control signal.

Abstract: A system for synchronizing circuit operation within an integrated circuit having a high frequency clock. The system includes an oscillator for providing a clock signal and a transmission line coupled to the oscillator for distributing the clock signal to load buffers. The load buffers provide sub-circuits within the integrated circuit with synchronized clock signals. The load buffers are resonant and convert the capacitive load impedance of receiving circuits into a virtual inductive load. The impedance converter boosts the clock signal transition times to provide improved high frequency circuit synchronization within the integrated circuit.

Abstract: A clock driver circuit includes a first and a second clock driver 15a and 15b. In each of these clock drivers, a plurality of main drivers 19(1) through 19(n) have their input nodes and output nodes connected respectively to a first and a second common line 18 and 21. The second common line 21 is connected to a plurality of clock signal supply lines 20(1) through 20(m) which in turn are connected to the clock input nodes of second macro cells 16 each requiring a clock signal. In a test mode, the clock signal supply lines 20a(1) through 20a(m) of the first clock driver 15a are connected respectively to the clock signal supply lines 20b(1) through 20b(m) of the second clock driver 15b by connection means 22. Thus, a clock driver circuit is provided which offers high driving ability with negligible clock skews in both normal mode and test mode.

Abstract: A plurality of macro cell layout regions 9 in cell regions 2 on a semiconductor substrate 1 are divided into three portions in a second direction. Each of the divided portions is provided with basic circuits 14a through 14c. In each basic circuit, a first common line 16 is connected to an output node of a clock input driver 11 via a clock output line 17. A plurality of predrivers 15(1) through 15(n) have their input nodes IN connected to the first common line 16 and have their output nodes OUT connected to a second common line 18. A plurality of main drivers 19(1) through 19mhave their input nodes IN connected to the second common line 18 and have their output nodes OUT connected to a third common line 20. The third common line is connected to a plurality of clock signal supply lines 21(1) through 21(s) commonly provided to the basic circuits 14a through 14c. The clock signal supply lines 21(1) through 21(s) are connected to clock input nodes of internal circuits 22 each requiring a clock signal.

Abstract: An LSIC includes a clock distributor circuit capable of decreasing the power consumption and suppressing the deviation of the power source potential and the transient current. The circuit includes a plurality of functional blocks including CPU. The CPU conducts a data accessing operation via address and data buses to peripheral blocks. There is also provided a clock supply unit to supply clock signals in which at least one of the clock signals has a phase different from those of the remaining clock signals and the clock signals do not accomplish the setting operation at the same time.

Abstract: Letting p be a definite integer, q be a varying integer from 1 to p, r be an arbitrary integer such that 1.ltoreq.r.ltoreq.p, and s be a varying integer from 2 to 2p+1, among a total of 2p+1 fan-like stages each having fan-out outputs thereof equalized to each other in load and number of associated fan-like stages, a respective 2q-th one comprises branch circuits each composed of one of a pair of logic gates, a 2r+1-th one comprises branch circuits each composed of a multi-input logic gate, a respective 2q-1-th one excepting the 2r+1-th one comprises branch circuits of which any one is composed of the other of the pair of logic gates, and a respective s-th one comprises branch circuits each respectively arranged within a cell layout region therefor and connected to an s+1-th stage at a vicinal location to a barycenter of the cell layout region to repeat a fan-out output of an s-1-th fan-like stage, as it is a clock signal distributed thereto.

Abstract: A clock network of a field programmable gate array has a first clock bus extending across the chip in a first dimension. A clock pad can be coupled to the first clock bus if the clock network is to be driven from the clock pad. An output of a selected logic cell can be coupled to the first clock bus if the clock network is to be driven from a logic cell. To increase speed of the clock network, the first clock bus is segmented (in one embodiment, collinearly extending segments can be selectively coupled together via selectively programmable antifuses) so that only a short piece of the first clock bus is used to couple either the pad or the logic cell to the clock network in high speed applications.

Abstract: A gated clock driver is configured to provide an enable signal and a gated clock signal at each of a plurality flip-flops. One of the p-channel transistors of the gated clock driver's NOR gate is distributed to each of the flip-flops or latches in the system. Additionally, an extra n-channel transistor is provided in the gated clock circuit to form an inverter with the nondistributed p-channel transistor. More particularly, the p-channel transistor that is driven by the system clock input is distributed to each of the flip-flops. Similarly, the enable input (at the output of the new inverter) is distributed to each of the flip-flops. Since the gated clock signal cannot be generated without the enable signal being high and the system clock being low, distributing enable and the p-channel transistor which receives the system clock as an input minimizes clock skew as compared to flip-flops with a completely shared clock gating clock.