Abstract: A clock generating device includes a divisor register, a reference clock generator, a first counter, a second counter, and a delay regulator circuit. The divisor register provides a divisor. The reference clock generator outputs a reference clock signal. The first counter counts a first number of cycles of the reference clock signal and generates a first count. The first counter outputs a first clock signal according to the first count and the divisor. The second counter counts a second number of cycles of the first clock signal and generates a second count. The second counter outputs a second clock signal according to the second count and a coefficient. The delay regulator circuit determines whether to control the first counter to delay outputting the first clock signal according to the first clock signal.

Abstract: A frequency divider includes a first shifter and a second shifter. The first shifter includes first to M-th clock control components connected together to form a first ring. The control components in the first shifter are controlled by an input clock signal such that signals are shifted along the first ring. An output of selected clock control components in the first shifter is provided as a carry signal of the first shifter. The second shifter includes first to N-th clock control components connected together to form a second ring. The control components in the second shifter are controlled by the carry signal of the first shifter such that the signals are shifted along the second ring. An output of selected clock control components in the second shifter is provided as a carry signal of the second shifter. M and N are integers greater than one.

Abstract: A programmable frequency divider includes a cascade of frequency-dividing units, each capable of dividing by a first or a second factor. Each unit receives an input clock and generates a divided output clock. Each unit receives a mode control signal that specifies when to divide its input clock by the second factor if a control input allows it, otherwise dividing the input clock by the first factor. The frequency divider is designed to support a range of divide ratios that requires one or more of the units to be non-operative or unused in some intervals. The final divided clock is generated using the mode control signal of the lowest unit in the cascade and the mode control signal of the highest unit that is never set to be non-operative or unused in supporting the range. As a result, duty-cycle variations of the final divided clock are minimized.

Abstract: An arithmetic counter circuit for high performance CMOS image sensors includes a plurality of flip-flops of a plurality of counter stages and a plurality of multiplexers of the plurality of counter stages being coupled to the plurality of flip-flops. Each of the plurality of multiplexers coupled to receive control signals including at least one of a toggle signal, a keep signal, a shift enable signal, or a mode signal. The control signals select the output of each of the plurality of multiplexers. Each of the plurality of flip-flops is coupled to be in one of a toggle state, a keep state, a reset state or a set state based on inputs received from the plurality of multiplexers. Other embodiments are described.

Abstract: A method an apparatus is provided to generate a gray code sequence from a sequence of binary values having a length “L”. Accordingly, one aspect of the present invention provides a circuit comprising a cycle flag toggle circuit configured to toggle a cycle flag between a first value and a second value, an intermediate value generator coupled to an output of the cycle flag toggle circuit configured to receive the binary value, and configured to generate an intermediate value from the cycle flag and the binary value, and a binary to gray converter coupled to an output of the intermediate value generator, configured to convert the intermediate value to a gray code.

Abstract: A data interface includes a network interface processor, a transmitter, and a receiver. The network interface processor is operably coupled to transceive parallel data via a network connection. The transmitter is operably coupled to convert outbound parallel data from the network interface processor into serial transmit data. The receiver is operably coupled to convert serial receive data into inbound parallel data, wherein the receiver provides the inbound parallel data to the network interface processor.

Abstract: A frequency divider for dividing a frequency of a clock signal by an odd divisor includes a flip-flop chain for latching signals having a number of flip-flops equal to the divisor. The frequency divider also has an XOR gate having two input nodes and an output node, one input node being electrically connected to the clock signal, the other input node being electrically connected to an inverted output node of the last flip-flop, and the output node of the XOR gate being electrically connected to clock input nodes of the odd flip-flops in the flip-flop chain. The frequency divider further has an inverter, an input node of the inverter being electrically connected to the output node of the XOR gate, an output node of the inverter being electrically connected to clock input nodes of the even flip-flops in the flip-flop chain.

Abstract: A method for generating a modulo Gray-code representation of a non-power-of-two set of binary values begins by determining a desired Gray-code sequence length. The method then continues by determining a bus width, M, in bits, based on the desired Gray-code sequence length, to represent the generated Gray-code. The method then continues by determining a set of skipped binary values based on the desired Gray-code sequence length and the bus width to obtain the non-power-of-two set of binary values. The method then continues by representing the non-power-of-two set of binary values as a set of equivalent Gray-code values.

Abstract: A non-power-of-two modulo N Gray-code counter (the “Gray-code counter”) and a binary incrementer-decrementer algorithm are disclosed.

Abstract: A non-power-of-two modulo N Gray-code counter (the “Gray-code counter”) and a binary incrementer-decrementer algorithm are disclosed.

Abstract: A technique for encoding index values of asynchronous pointers for a non-power-of-two sized buffer that supports the unit distance property. The technique includes converting N+1 pointer index values corresponding to index locations 0 through N of the buffer from the natural binary-coded decimal format to a unit distance code format such as the gray code, adding a 0 bit in the MSB position of each of the N+1 converted pointer index values, adding a first pointer index value at index location N+1 equal to the pointer index value at index location N except that a 1 bit replaces the 0 bit in the MSB position, and adding a plurality of pointer index values at index locations greater than N+1 but less than or equal to N+n+1 that are equal to the first added pointer index value, where “n” equals the number of bits in each pointer index value prior to conversion.

Abstract: A gray-code counter system (AP1) for a RAM-based FIFO comprises a read pointer (10), a write pointer (20), and a detector (30). The read pointer includes a gray-code decoder (11), a binary incrementer (12), a gray-code encoder (13), and a register (14) that holds the pointer count). The binary incrementer increments by 1 except when the input is 0110 (decimal 6) or 1110 (decimal 14); in these cases, it increments by 3. The result is a 4-bit modulo-12 gray-code sequence with the twelve allowed gray-code values being distributed among the sixteen possible 4-bit gray code values with translational and reflective bilateral symmetry. The write pointer is similar. Because of the translational symmetry, detectors that work with counters with modulo numbers that are power of two work with the corresponding non-power-of-two counter to provide “full” and “empty” indications.

Abstract: A phase locked loop includes a voltage controlled oscillator (VCO) for generating output VCO pulses. A frequency divider divides the VCO pulses by a variable number to produce frequency divided pulses whose phase is compared with that of input reference pulses by a phase detector. An update pulse is produced by the phase comparator having a pulsewidth corresponding to the detected phase difference. A pulse generator generates a train of update pulses having a combined pulsewidth equal to the pulsewidth of the update pulse, with the update pulses being substantially equally distributed within each period of the reference pulses to produce low output ripple. The update pulses are integrated by a loop filter to produce a D.C. control voltage that controls the VCO to vary the frequency of the VCO pulses such that the phase difference is adjusted toward zero. The frequency divider comprises a binary counter and a controller that enable the frequency divider to divide by a number N that is not a power of 2.

Abstract: A method and circuit for selectively scaling a binary counter having N serially connected stages in which an output count from the counter is 2.sup.M times the number of clock signals that have been input to the counter. The first M stages of the counter are selectively held so that clock signals by-pass (or pass through) the first M stages without change. The M+1 stage receives each clock signal and is thereby caused to indicate that 2.sup.M clock signals have been received, when only one clock signal has, in fact, been received. The output of each stage is provided to a decoder array that provides the scaled count signal. The method and circuit find application in systems in which normal unscaled operation of the binary counter may be selectively replaced with high speed operation, such as during tests or during special operating modes. The circuit and method obviate the need for a separate high speed clock, or for adaptive circuitry in the decoder array.

Abstract: A circuit configuration generates an even-numbered duty factor with an odd-numbered division n of a symmetrical clock signal. A first device generates a first output signal from the symmetrical clock signal. The first output signal begins upon each n.sup.th edge of one type, of a symmetrical clock signal and remains active for a length of N-1/2 periods of the symmetrical clock signal. A second device generates a second output signal from the symmetrical clock signal. The second output signal begins upon each n.sup.th edge of another type, of the symmetrical clock signal and remains active for the length of N-1/2 periods of the symmetrical clock signal. A logic linkage is connected to the first and second devices for linking the two output signals to form one symmetrical output signal.

Abstract: The clock signal generator of the present invention divides a higher frequency clock down to a frequency that is an uneven sub-multiple of the higher frequency. The input clock to be divided down clocks an 11-bit counter (105-110) that outputs an overflow signal to a D flip-flop (125). The D flip-flop generates a load signal that resets the counter after 1025 clock periods. The load signal also suppresses, after 1025 clock periods, the toggling of another toggle flip-flop (120) that provides a divide by two clock. By suppressing a clock pulse in the divide by two clock, every 1025 clock pulses of the higher frequency clock, the average clock frequency of the divide by two clock is reduced to an uneven sub-multiple of the higher clock frequency.

Abstract: A frequency dividing circuit divides an input signal of an input frequency into an output signal of an output frequency. The frequency dividing circuit comprises first through fourth latch circuits which operate the input signal, respectively. The first latch circuit delays an original signal into a first delay signal. The second latch circuit delays the first delay signal to produce a second delay signal and a first inverted delay signal which has an antiphase relative to the second delay signal. The third latch circuit delays the second delay signal into a third delay signal as the output signal. The fourth latch circuit receives a first OR signal which is produced by logically adding the third delay signal and mode signal which has first and second levels. The fourth latch signal delays the first OR signal into a fourth delay signal and produces a second inverted delay signal which has an antiphase relative to the fourth delay signal.

Abstract: A scaler comprising a plurality of flip-flops, varies its frequency division to correct phase by 0.5 clock cycle. Each flip-flop is continuously and synchronously responsive to either a rising or a falling edge of the clock pulses. Normally, the scaler's state transits along one of two loops, which generate output pulses having identical repetition rates. When a control signal is applied, the scaler's state transits from one loop to the other, generating at least one output at an alternative repetition rate. The alternative repetition rate is either lower or higher than the identical repetition rate by an integral number of half cycles of the input clock pulses. Where there are two control signals, a lower or higher alternative repetition rate can be selected. Since the flip-flops are responsive to either edge of the clock pulses without clock gating interruptions, there is no jitter and the scaler's robustness is improved. Also the clock frequency can be effectively halved.

Abstract: An asynchronous nonlogical counting device includes at least a first counter and a second counter connected in cascade. The first counter has a frequency dividing ratio of 2.sup.n where n is a natural number. A control unit produces a control signal based on the count value of the first counter. The second counter has a variable frequency dividing ratio which is based on the control signal. The counting device can be made programmable by substituting a comparator circuit for the control unit. The comparator compares the output of the first counter to an instruction signal from an external source.

Abstract: A high speed CMOS divide by 4/5 prescaler circuit comprises first, second, third, fourth, and fifth inverter stages. When a modulas control signal is low, the prescaler operates as five clocked inverters in series having an output which is fed back to the input of the initial stage. That is, the circuit operates as a five stage clocked ring oscillator wherein only one output changes on each clock edge. When a modulas control signal is high indicating that a divide by four is desired, the counter operates as a five stage ring oscillator for seven clock edges. On the eighth edge, feed forward circuitry forces the last three stages to change states simultaneously.

Abstract: A circuit for dividing a clock signal by two and one-half (2.5) is shown. The divide by two and one-half (2.5) circuit includes a clock selector circuit arranged to output a selected polarity of the first clock signal. A ring counter arranged to receive the clock selector circuit output signal, and output a signal that has a period of 3 times (3.times.) the signal received from the clock selector circuit. A divide by two circuit connected to the ring counter circuit and to the clock selector circuit. The divide by two circuit divides the ring counter output signal by two to produce an output signal. The divide by two output signal is then fed back to the clock selector circuit to regulate the selection of the first clock signal polarity, causing the ring counter to output a clock signal with a period of two and one-half times (2.5.times.) the first clock signal.

Abstract: A frequency divider circuit for dividing an input signal with a predetermined integer or non-integer divisor. The frequency divider circuit comprises a polynomial counter, decode logic, and a clock edge selector. The polynomial counter, responsive to a clock signal at a predetermined frequency, cycles through a predetermined set of logic states which are logical combinations of the previous state, and generates a set of output signals which indicates the present logic state of the polynomial counter. The decode logic, responsive to the output signals of the polynomial counter, implements a predetermined logical mapping of said output signals into a decoded output signal. The clock edge selector, responsive to the decoded output signal of the decode logic, utilizes flip-flops and other logic to generate integer and non-integer multiples of the clock signal. The frequency divider circuit selects either integer or non-integer divisors depending on the informational content of a control signal.

Abstract: A circuit for dividing a master clock by an odd integral value and producing a 50% duty cycle. A state machine develops set and clear signals which are of a timing proportion of n: n+1, where 2n+1 is the divisor value. The set signal is provided to one input of a bistable multivibrator or S-R latch to set the multivibrator to a given state, while the clear signal is combined with the master clock signal to delay or disable the clearing of the multivibrator by 1/2 count of the master clock, so that an n+1/2: n+1/2 proportion output clock signal is developed. Additionally, the circuit includes a state machine which determines which of a series of differing frequency master clock signals is active and when an external triggering event occurs so that the following rising edge of the output clock signal is delayed until a determined time after the triggering event to allow synchronization of the output clock signal.

Abstract: The invention is a digital record/playback apparatus including an input digital filter, and A/D converter, a solid state memory, a D/A converter and an output digital filter. The entire system is driven off a single clock source which allows the frequent response of the filters to be modified simultaneous with the sampling frequency of the A/D and D/A converter. This allows the record/playback apparatus to record low frequency signals, such as medical data, as well as relatively high frequency signals such as voice, by simply changing the frequency of the clock source. In addition, the apparatus includes an expandable memory which allows recording of up to one hour or more of program material.

Abstract: A frequency divide by n circuit, where n is an odd number, which includes means for splitting an incoming clock signal of frequency "f" into two non-overlapping complementary clock signals of frequency "f" and a shift register circuit. The shift register circuit is coupled to the signal splitting means and generates an output clock signal of frequency f/n in response to the two complementary clock signals. The output clock signal has a duty cycle equal to ((n-1)/2+D.sub.in)/n where D.sub.in is the duty cycle of the incoming clock signal. The output duty cycle is substantially independent of processing and operating conditions.

Abstract: An improved, high-speed frequency divider circuit (32) is presented. The frequency divider circuit (32) is comprised of three D-type flip-flops (34, 36 38). The three flip-flops (34, 36, 38) are clocked synchronously for higher speed of operation. The design of the frequency divider circuit (32) embodies a sagacious state assignment to minimize the number of bits that change state on any given state transition, thus reducing the possibility of faulty circuit operation.

Abstract: The majority circuit has an (n+1)/2-notation counter circuit comprising a plurality of cascade-connected binary counters. An odd number of n-bit serial data are counted by the counter circuit, and an output of the binary counter of the last stage is taken out as a majority output of the majority circuit.

Abstract: A variable-ratio frequency divider has a D flip-flop which makes possible high-speed operation, and the number of frequency divisions is made variable by changing the transmission delay time of a delay element included in a feedback loop from the output Q to a predetermined terminal of the D flip-flop.

Abstract: A variable frequency divider which includes a feedback shift register having a feedback gate of NOR type, a delay shift register for delaying output data from the feedback shift register by one clock, a control shift register having a control gate of AND type, a feedback circuit for feeding output data from the delay shift register and from the control shift register back to the feedback gate, and an expander which receives output data from the feedback shift register and produces a control signal according to said frequency dividing input and a frequency division ratio instruction signal. The control gate receives output data from the delay shift register and the control signal.

Abstract: Diode load emitter coupled logic circuits is described that utilizes forward biased diodes in the load circuits. The load circuits may be comprised of a single diode or two or more diodes connected in series. If a single diode is used in the load circuits, the slope factor of the diode must be greater than or equal to the slope factor of switching transistors in the logic circuit. External bias circuitry provides a bias current which can be varied for varying the frequency of operation of the logic circuit. High speeds at low power dissipations can be obtained since the switching transistors in the logic circuits do not switch completely on and off.

Abstract: A method and apparatus for generating two phase locked digital clocks of different word rates particularly suited for a graphic and alphanumeric computer display terminal. Master and slave clock generators are used to generate output pulses at every N-th and M-th clocks of a common clock. A phase lock loop including the master clock generator and a phase lock counter dividing the common clock by the factor of the least common multiple of N and M is used to synchronize the slave clock generator.

Abstract: A method and apparatus is described for dividing a clock frequency by any odd number to obtain a symmetrical output. Generally, some dividers in a chain of divide-by-two dividers are designated as controlled dividers and others are designated as uncontrolled dividers. The clock input of each controlled divider receives the output of an exclusive NOR gate, the inputs to which include the output of the last divider in the chain and either the clock signal or the output of a preceding divider, depending on certain criteria. The clock input of each uncontrolled divider receives the output of an immediately preceding divider. With this arrangement, the last divider in the chain develops a divided output which is symmetrical.

Abstract: The ring counter of this invention is self-initializing and is operable at a clock frequency corresponding to four gate delays and comprises a plurality of master of slave flip-flops, in which this high speed capability is attained by using non-inverting feedback between the first and last flip-flops and by operating the master and slave of each in complementary fashion without requiring the use of a complementary clock signal. The non-inverting feedback takes advantage of the inherent delay between the response of the complementary outputs of each flip-flop.

Abstract: In utilizing frequency dividers at high frequencies the maximum operating frequency is determined by the delay time through the frequency divider. To minimize this delay time, a digital frequency divider is provided having a binary counter constructed of flip-flops and a shift register coupled to the output of said counter, wherein the output state of the shift register is forcibly reduced to a low level in response to a control signal for varying the number of frequency division of said counter. A circuit is also provided for feeding the input terminal of the flip-flop at the first stage of said counter with an OR output made up of the outputs of said shift register and said counter. Thus, the digital frequency divider can operate at a speed which is limited only by the toggle frequency of said flip-flop circuits.