Abstract: The present invention relates to a clock signal generating circuit and a power supply including the same. The present invention includes: a counter for counting one period of an input clock signal by using a reference clock signal, and generating a count signal; and a clock signal generator for receiving the count signal and the reference clock signal, dividing the count signal to generate a quotient and a remainder, setting the quotient as a reference period of an output clock signal, and distributing and disposing the remainder to the output clock signal with a plurality of periods occurring for one period of the input clock signal.

Abstract: Embodiments of the invention provide a DPD system where the transmit reference signal is transformed, including sub-sampling, frequency translation, and the like, to match the feedback signal, which goes thru a similar transformation process, to obtain an error signal. The same transformation is applied to a system model, which may be Jacobian, Hessian, Gradient, or the like, in an adaptation algorithm to minimize error.

Abstract: A clock generator utilized for providing a clock signal includes: a first oscillator and a switching circuit. The switching circuit is coupled to the first oscillator and a second oscillator, and utilized for receiving a first oscillating signal generated from the first oscillator and a second oscillating signal generated from the second oscillator, and selecting one of the first oscillating signal and the second oscillating signal as the clock signal according to a status signal.

Abstract: A resonant clock distribution network architecture is proposed that uses clock drivers of programmable size and reference clocks of programmable duty cycle to achieve a target clock rise time and clock amplitude with low energy consumption when operating in any one of multiple clock frequencies in resonant or non-resonant mode. Such a network is generally applicable to semiconductor devices with various clock frequencies, and high-performance and low-power clocking requirements such as microprocessors, ASICs, and SOCs.

Abstract: Signal synchronizers synchronize input signals with a clock signal. The input of each synchronizer is connected to a first input and the output of each synchronizer is connected to a second input of a respective first gate arrangement. The first gate arrangements provide an output signal only if there is an input signal on the first input and none on the second input or vice versa. The outputs of each of the first gate arrangements is connected to respective inputs of a second gate arrangement, which provides an output signal if there is a signal on any of its inputs. The output of the second gate arrangement is connected to a third gate arrangement which operates such that the clock signal to the synchronizers is only enabled when there is a change to the state of a signal received at the input of at least one of the synchronizers.

Abstract: A display substrate includes a base substrate including a display area and a peripheral area, a pixel disposed on the display area, wherein the pixel includes; a pixel transistor connected to a gate line and a data line which cross each other, and a pixel electrode connected to the pixel transistor and the pixel electrode, and a gate driving circuit disposed on the peripheral area, wherein the gate driving circuit outputs a gate signal to the gate line and comprises a plurality of stages, an n-th stage of the gate driving circuit including a plurality of circuit transistors and a boosting capacitor including a first capacitor and a second capacitor, the plurality of circuit transistors and the first capacitor being disposed on a first area and the second capacitor being disposed on a second area of the peripheral area positioned between the first area and the display area.

Abstract: In an asymmetrically terminated communication system, the power consumed to transmit a particular bit value is adjusted based on whether the bit being output is the second, third, fourth, etc. consecutive bit with the same value after a transition to output the particular bit value. The adjustment of the power consumed to transmit the two or more consecutive bits with the same value may be made by adjusting the driver strength during the second, or subsequent, consecutive bits with the same value. The adjustment of the power consumed is performed on the bit value that consumes the most DC power and the other value is typically not adjusted.

Abstract: The clock generation method contains the following steps. In a pulse recognition step, an input pulse signal is first filtered to remove a shorter signal. Then, a width digitization calculation is conducted on the remaining pulse signal. Based on the width digitization calculation, a signal is recorded and a period of the recorded signal is determined. The value of the period is delivered to a gain module. In a step for verifying the input value to D/A converter, two values are input to a D/A converter from the gain module, and the output from the D/A converter is delivered to an oscillator. The gain module determines a desired input value from the gain module to the D/A converter. In a pulse generation step, the gain module inputs the desired input value to the D/A converter which in turn delivers to the oscillator for the generation of a corresponding clock.

Abstract: Apparatus and methods are provided for an extraction circuit. In one configuration, an apparatus includes: an edge extraction circuit for receiving a first clock signal and outputting a second clock signal, wherein a duty cycle of the second clock is substantially smaller than a duty cycle of the first clock; a transistor for receiving the second clock signal and outputting a current signal; a transmission line for receiving the current signal on a first end and transmitting the current signal to a second end; a termination circuit for receiving the current signal at the second end and converting the current signal into a voltage signal; and an edge detection circuit for outputting a third clock by detecting an edge of the voltage signal. In one embodiment, the edge detection circuit comprises an inverter. In another embodiment, the edge detection circuit comprises a comparator.

Abstract: There is provided a frequency synthesizer capable of improving phase noise. A sinusoidal signal with a frequency set by a frequency setting part is output as a digital signal from a set signal output part, and the digital signal is D/A-converted. A difference between a sinusoidal signal with a frequency corresponding to an output frequency of a voltage controlled oscillating part and a sinusoidal signal output from a D/A converting part is amplified by a differential amplifier, and an amplified signal is input via an A/D converting part to a means for extracting a phase difference between the aforesaid sinusoidal signals. A voltage corresponding to a signal being the result of integration of the phase difference is input as a control voltage to the voltage controlled oscillating part. Then, a gain of the differential amplifier is set larger than a maximum value of phase noise degradation of the A/D converting part, whereby the phase noise degradation of the A/D converting part is cancelled.

Abstract: An integrated circuit device includes a clock delay circuit configured to receive a clock signal and a pulse signal and to produce an output signal therefrom. The clock delay circuit is configured to transition the output signal to a first state responsive to a first state of the clock signal and to transition the output signal to a second state responsive to a first state transition of the pulse signal. The integrated circuit device further includes a pulse generator circuit configured to receive the clock signal and the output signal and to produce the pulse signal therefrom. The pulse generator circuit is configured to generate the first state transition in the pulse signal responsive to a transition of the clock signal to a second state and to generate a second state transition in the pulse signal responsive to the transition of the output signal to the second state.

Abstract: A mode determination circuit is configured to determine whether there is a status change of the electric system associated with a frequency variation of a system control clock, and a clock change circuit is configured to change the system control clock from a system clock to a monitoring clock based on a determination result obtained by the mode determination circuit.

Abstract: Systems and methods for generating pulse clocks with programmable edges and pulse widths configured for varying requirements of different memory access operations. A pulse clock generation circuit includes a selective delay logic to provide a programmable rising edge delay of the pulse clock, a selective pulse width widening logic to provide a programmable pulse width of the pulse clock, and a built-in level shifter for shifting a voltage level of the pulse clock. A rising edge delay for a read operation is programmed to correspond to an expected read array access delay, and the pulse width for a write operation is programmed to be wider than the pulse width for a read operation.

Abstract: A clock distribution system for a multi-bit latch. The clock distribution system may include a plurality of branches, each connected to a common clock input. Each branch may be driven by an input clock buffer. Each branch may be connected to clock inputs of a predetermined number of latch stages within the multi-bit latch. A predetermined number of clock branches may include a clock output buffer. The number of clock output buffers may be less than the total number of latch stages. In this manner the clock distribution system may reduce the feed through capacitance of the latch stages, which may mitigate the latch transition skew for each latch stage.

Abstract: A delay circuit includes a pulse generation unit configured to generate a pulse signal, which is activated in response to an input signal and has a pulse width corresponding to delay information, and an output unit configured to activate a final output signal in response to a deactivation of the pulse signal.

Abstract: A resonant clock distribution network architecture is proposed that enables a resonant clock network to track the impact of parameter variations on the insertion delay of a conventional clock distribution network, thus limiting clock skew between the two networks and yielding increased performance. Such a network is generally applicable to semiconductor devices with various clock frequencies, and high-performance and low-power clocking requirements such as microprocessors, ASICs, and SOCs.

Abstract: Aspects of the disclosure provide an integrated circuit. The integrated circuit includes a signal generation circuit. The signal generation circuit is configured to generate a first output signal and a second output signal in response to a reference signal. The first output signal and the second output signal are a pair of complementary signals. The first output signal has first transitions of a first polarity and second transitions of a second polarity. The second output signal has third transitions of the second polarity that are simultaneous to the first transitions in the first output signal and has fourth transitions of the first polarity non-simultaneously corresponding to the second transitions in the first output signal.

Abstract: A counting circuit of a semiconductor device includes a plurality of counting units configured to count respective bits of counting codes in response to a plurality of counting clocks, respectively, and to control in a counting direction in response to a counting control signal; a clock toggling control unit configured to control the number of counting clocks that toggle among the plurality of counting clocks in response to clock control signals; and a counting operation control unit configured to compare a value of target codes and a value of the counting codes, and to determine a value of the counting control signal according to a comparison result.

Abstract: A delay measuring circuit includes a first trigger-signal generating unit that, when a value of a signal input to a circuit under test, changes, generates a first trigger signal. The delay measuring circuit includes a second trigger-signal generating unit that, when a value of a signal output from the circuit under test changes, generates a second trigger signal. The delay measuring circuit includes a delay unit that includes a plurality of delay elements connected in series. The delay measuring circuit includes a delay information retaining unit that individually captures and retains the first trigger signal output from each of the delay elements included in the delay unit between when the first trigger signal is generated by the first trigger-signal generating unit and when the second trigger signal is generated by the second trigger-signal generating unit.

Abstract: A pulse generator is provided. The pulse generator includes: a time delayed pulse generation unit including a plurality of delay cells for receiving a first pulse having a first pulse width and outputting pulses delayed by a particular time delay value on the basis of one of a rising edge and a falling edge of the first pulse; an edge combiner configured to receive the plurality of time delayed pulses from the time delayed pulse generation unit and generate second pulses having a second pulse width; and a channel selector configured to regulate the number of outputs of the second pulses generated by the edge combiner.

Abstract: A method for reducing spurious for a clock distribution system, the method including a) providing a system controller, b) providing clock distribution system, c) inputting characteristics of the clock distribution system in advance of operation thereof, d) calculating an expected level of the integer boundary spurious as a function of a fractional offset value, e) selecting an integer boundary solution based on the fractional offset value being within a preferred predetermined region, and f) programming the master clock subsystem and the one or more fractional synthesizers with the integer boundary solution, and g) repeating steps d) through f) as needed.

Abstract: A method for generation of high frequency, non-overlapping clocks may include receiving input clock signals at a clock input node of a circuit. Multiple feedback signals may be received at a number of input feedback nodes of the circuit. At a startup node, a startup signal of the circuit may be received, and, in response to receiving the startup signal, an output clock may be generated at a predefined portion of at least one of the received input clock signals. A stable high frequency output clock may be generated at an output stage by utilizing the feedback signals received by the input feedback nodes.

Abstract: A device and a method for eliminating transitions in discrete signals. The working of the device and method is based on allowing the charge of a capacitor with one state when the state opposite the state to which it has been assigned is produced and allowing their discharge through a corresponding capacitor when their state is active. The signal is advantageously consolidated without needing processors or programs, is very simple, there is increased reliability, and the device can very easily be integrated in any sensor, such as those used in aircraft.

Abstract: The present invention relates to a clock signal generating circuit and a power supply including the same. The present invention includes: a counter for counting one period of an input clock signal by using a reference clock signal, and generating a count signal; and a clock signal generator for receiving the count signal and the reference clock signal, dividing the count signal to generate a quotient and a remainder, setting the quotient as a reference period of an output clock signal, and distributing and disposing the remainder to the output clock signal with a plurality of periods occurring for one period of the input clock signal.

Abstract: A system and method are disclosed for generating a high accuracy and low power on die reference clock. An LC clock is generated on die and a frequency divider lowers the LC clock frequency to a target reference frequency. An RCO clock is generated on die with an unknown initial frequency. The RCO clock and target reference clock are compared to determine in which direction the frequency of the RCO clock should be adjusted to move closer to the target reference frequency. A signal is sent causing a current source or capacitor in the RCO circuit to be modified. Therefore, the RCO clock frequency is adjusted. The RCO circuit is repeatedly adjusted until the RCO clock frequency is sufficiently accurate. The LC clock is disabled to conserve the power that would have been consumed in generating the LC clock.

Abstract: A gate driving circuit includes a first clock generator to output n output control clock pulses having different phases; a second clock generator to create m*n output clock pulses having different phases and partially overlapped with one another in high periods thereof, to arrange the m*n output clock pulses in sequence of phase, to bind the m*n output clock pulses arranged in sequence of phase in units of n to generate m groups, each of which has n output clock pulses, and to output the m*n output clock pulses so that a rising edge of an output clock pulse having a k-th sequence of phase included in each group is located in a high period of an output control clock pulse having a k-th sequence of phase among the n output control clock pulses; and a shift register sequentially outputting a plurality of scan pulses.

Abstract: An on-board battery charging system for a plug-in electric vehicle has a charging unit for charging a high-voltage battery and a controller for controlling and managing current flow used to support charging related operations for the high-voltage battery. The controller may detect a connection between the on-board battery charging system and electric vehicle supply equipment (EVSE) and is configured to enter a sleep mode when a control pilot signal from the EVSE is either absent or indicative of a delayed charge mode. The charging system may include a wake-by-control pilot circuit operable to wake the controller from the sleep mode when the control pilot signal is detected and when the control pilot signal transitions from a non-zero static DC voltage to an active PWM signal.

Abstract: To provide a pulse signal output circuit and a shift register which have lower power consumption, are not easily changed over time, and have a longer lifetime. A pulse signal output circuit includes a first input signal generation circuit; a second input signal generation circuit; an output circuit which includes a first transistor and a second transistor and outputs a pulse signal in response to a signal output from the first and second input signal generation circuits; a monitor circuit which obtains the threshold voltages of the first and second transistors; and a power supply output circuit which generates a power supply potential raised by a potential higher than or equal to a potential which is equal to or substantially equal to the threshold voltage and supplies the power supply potential to the first and second input signal generation circuits. A shift register includes the pulse signal output circuit.

Abstract: In an A/D conversion circuit and an imaging device, an upper counter acquires a first upper count value by performing counting using one output signal, which constitutes a first lower phase signal output from a delay circuit, as a count clock. After values of bits constituting the first upper count value are inverted, the upper counter acquires a second upper count value by performing counting using one output signal, which constitutes a second lower phase signal output from the delay circuit, as a count clock, and further performing counting based on an upper count clock output from a lower counter. A modification unit modifies a logic state of a count clock to a predetermined state when the count clock of the upper counter is switched.

Abstract: A clock generator includes a counter unit receiving a reference clock signal to generate a timing signal, a selector receiving the timing signal to output a clock enable based on bit string data stored in a storage unit and a clock gate cell receiving the reference clock signal based on the clock, thinning some pulses out from the reference clock signal based on the clock enable so that a clock signal is maskable, and outputting an inter intermittent clock signal.

Abstract: The clock generation method contains the following steps. In a pulse recognition step, an input pulse signal is first filtered to remove a shorter signal. Then, a width digitization calculation is conducted on the remaining pulse signal. Based on the width digitization calculation, a signal is recorded and a period of the recorded signal is determined. The value of the period is delivered to a gain module. In a step for verifying the input value to D/A converter, two values are input to a D/A converter from the gain module, and the output from the D/A converter is delivered to an oscillator. The gain module determines a desired input value from the gain module to the D/A converter. In a pulse generation step, the gain module inputs the desired input value to the D/A converter which in turn delivers to the oscillator for the generation of a corresponding clock.

Abstract: A signal generator includes: an adjusting circuit arranged to adjust a first amplitude of an oscillating signal to generate an adjusted oscillating signal; and a resistor ladder circuit arranged to receive the adjusted oscillating signal to generate a plurality of candidate output oscillating signals having a plurality of different amplitudes respectively and output an output oscillating signal selected from the candidate output oscillating signals.

Abstract: An object is to suppress change of a threshold voltage of a transistor in a shift register and to prevent the transistor from malfunctioning during a non-selection period. A pulse output circuit provided in the shift register regularly supplies a potential to a gate electrode of a transistor which is in a floating state so that the gate electrode is turned on during a non-selection period when a pulse is not outputted. In addition, supply of a potential to the gate electrode of the transistor is performed by turning on or off another transistor regularly.

Abstract: A transceiver comprises a transmitter that converts a plurality of data components into serial data in response to a first clock signal and transmits the serial data, and a receiver that receives the serial data and converts the serial data into the plurality of data components in response to a second clock signal generated from the serial data. The transmitter adds at least one dummy bit to the serial data at predetermined intervals. The at least one dummy bit includes information regarding a data type of the plurality of data components.

Abstract: Techniques for decimating a first periodic signal to generate a second periodic signal. In an exemplary embodiment, the first periodic signal is divided by a configurable integer ratio divider, and the output of the divider is delayed by a configurable fractional delay. The configurable fractional delay may be noise-shaped using, e.g., sigma-delta modulation techniques to spread the quantization noise of the fractional delay over a wide bandwidth. In an exemplary embodiment, the first and second periodic signals may be used to generate the transmit (TX) and receive (RX) local oscillator (LO) signals for a communications transceiver from a single phase-locked loop (PLL) output.

Abstract: A method of compensating clock skew may include generating (2M+1) detected values by applying (2M+1) delay clock signals to (2M+1) pieces of delay data, wherein M is a natural number, determining a dominant logic value based on a comparison of a number of logic high detected values and a number of logic low detected values from among the (2M+1) detected values, determining a median delay time based on a number of the (2M+1) detected values having the dominant logic value, and adjusting a phase of a clock signal using the median delay time.

Abstract: An integrated circuit includes a local clock network that is operable to provide a first clock signal and an interface circuit that is coupled to receive the first clock signal from the local clock network. The interface circuit is operable to generate a second clock signal based on the first clock signal. A clock line is coupled to the interface circuit. The clock line has a fixed length. The second clock signal is provided to a multiplexer circuit through the clock line. The multiplexer circuit provides a third clock signal based on the second clock signal. Another clock network is coupled to receive the third clock signal from the multiplexer circuit.

Abstract: Embodiments are provided wherein a bandwidth of a waveform sequence that is transmitted by a transmitter in order to convey information is varied. According to additional embodiments, a set of frequencies that is used to provide frequency content to the waveform sequence is also varied and comprises non-contiguous first and second frequency intervals wherein a third frequency interval that is between the first and second frequency intervals remains devoid of providing frequency content to the waveform sequence in order to avoid interference. The invention is relevant to 4G LTE carrier aggregation systems/methods and/or other aspects of 4G LTE. Various transmitter/receiver embodiments are disclosed including direct synthesis transmitter/receiver embodiments.

Abstract: A clock source is configured to provide an oscillating signal to be divided into a clock signal. A temperature sensor senses a first temperature of the clock source. The clock source is subjected to at least one second temperature implemented by a temperature alteration module. A calibration module calibrates the clock signal based on the at least one second temperature, the first temperature, a reference signal, and the oscillating signal at the at least one second temperature.

Abstract: A signal transmitting apparatus for orthogonal frequency division multiplexing (OFDM) system comprises a compandor, a predistortor, a power amplifier and a feedback module. The compandor is configured to compress and expand a transmitted signal. The predistortor is configured to perform a predistortion operation on output signals of the compandor. The power amplifier is configured to amplify output signals of the predistortor. The feedback module is configured to adjust parameters of the compandor and the predistortor based on a feedback signal.

Abstract: A first plurality of clock signals including a first clock signal and a second clock signal is received, the first and second clock signal out of phase with each other. A second plurality of clock signals comprising a third clock signal and a fourth clock signal is received, the third and fourth clock signals out of phase with each other. A plurality of enable signals are received. A fifth clock signal is determined based on the first plurality of clock signals and the plurality of enable signals. A sixth clock signal is determined based on the second plurality of clock signals and the plurality of enable signals. A seventh clock signal is determined based on the fifth clock signal and the sixth clock signal.

Abstract: A semiconductor apparatus may include a transmission control signal generation unit, a fuse signal transmission unit, a reception control signal generation unit and a fuse signal reception unit. The transmission control signal generation unit receives a clock signal and generates a plurality of divided clock signals based on the clock signal to output transmission control signals from the plurality of divided clock signals. The fuse signal transmission unit transmits fuse information in synchronization with the transmission control signals. The reception control signal generation unit receives the clock signal and generates the plurality of divided clock signals, and generates reception control signals based on the plurality of divided clock signals. The fuse signal reception unit receives the fuse information in synchronization with the reception control signals.

Abstract: A system for automatically transforming a given synchronous circuit description into an equivalent and provably correct desynchronized circuit description. Included in the automated transformation are techniques for synthesizing a variability-aware controller using a two-phase protocol, techniques for synthesizing a variability-aware controller using gated clocks and testability circuits, techniques for synthesizing a variability-aware controller optimized for performance, techniques for initializing the synthesized controller, techniques for dynamically minimizing power requirements, and techniques for interfacing the desynchronized circuit with external synchronous circuits. Also disclosed are techniques for implementing a system for automatically transforming a synchronous circuit description into an equivalent and provably correct desynchronized circuit description within the context of an electronic design automation design flow.

Abstract: The present invention provide a clock circuit and a method for providing a clock signal. The clock circuit includes: an adaptive clock generation circuit, configured to output an adaptive clock signal; and an adaptive clock driven circuit, configured to be driven by the adaptive clock signal to work. A maximum workable frequency of the adaptive clock driven circuit is higher than or equal to a frequency of the adaptive clock signal. When a working condition of the adaptive clock driven circuit is changed, the maximum workable frequency of the adaptive clock driven circuit is changed, the frequency of the adaptive clock signal which is output by the adaptive clock generation circuit is changed, and a changing direction of the frequency of an adaptive clock signal is consistent with that of the maximum workable frequency. The clock circuit and method may be used in design or manufacturing of a digital circuit.

Abstract: There is provided a synchronization circuit for a 3D chip stack having multiple circuits and multiple strata interconnected using a first and a second stack-wide broadcast connection chain. The synchronization circuit includes the following, on each stratum. A synchronizer connected to the first connection chain receives an asynchronous signal therefrom and performs a synchronization to provide a synchronous signal. A driver is connected to the second chain for driving the synchronous signal. A latch connected to the second chain receives the synchronous signal driven by the driver on a same or different stratum within a next clock cycle from the synchronization to provide the stack-wide synchronous signal to a circuit on a same stratum. An output of a single driver on one stratum is selected at any given time for use by the latch on all strata.

Abstract: A spread spectrum clock signal generator and an accompanying method provide a spread spectrum clock signal of a reduced electromagnetic interference. The spread spectrum clock signal generator includes (a) a state machine, which maintains a current state of the spread spectrum clock signal generator, receives as input value a next state of the spread spectrum clock signal generator and generates a clock phase selection signal based on the current and next states; (b) a random number generator for generating the next state; and (c) a waveform generation circuit for generating a spread spectrum clock signal based on the clock phase selection signal.

Abstract: Circuits and methods for latch-tracking pulse generation across process, voltage and temperature (PVT) variations are disclosed. In one embodiment, the method includes receiving a clock input at a pulse generation circuit and generating a pulse at the pulse generation circuit in response to the clock input. The method further includes distributing the pulse to a mimic latch, which writes a mimic storage node through a mimic storage circuit of the mimic latch in response to the pulse. The method further includes terminating generation of the pulse at the pulse generation circuit in response to a transition of the mimic storage node. The method may include receiving a clock enable input at a pulse control circuit coupled to the pulse generation circuit and either suppressing or allowing generation of a pulse in response to a value of the clock enable input.

Abstract: Methods and apparatuses provide a clocked digital device having dynamically adjustable operating characteristics. The digital device comprises a digital clock management (“DCM”) circuit in which the amount of delay between receipt of an active edge of a clock signal at the input of the DCM circuit and appearance of an active edge of another clock signal at the output of the DCM circuit depends on a phase adjustment signal applied to the DCM circuit's phase adjust input. A phase adjustment circuit provides the phase adjustment signal to the DCM circuit's phase adjust input for controlling the amount of the delay between the clock signal at the input of the DCM circuit and the clock signal at the output of the DCM circuit.

Abstract: The clock generation method contains the following steps. In a pulse recognition step, an input pulse signal is first filtered to remove a shorter signal. Then, a width digitization calculation is conducted on the remaining pulse signal. Based on the width digitization calculation, a signal is recorded and a period of the recorded signal is determined. The value of the period is delivered to a gain module. In a step for verifying the input value to D/A converter, two values are input to a D/A converter from the gain module, and the output from the D/A converter is delivered to an oscillator. The gain module determines a desired input value from the gain module to the D/A converter. In a pulse generation step, the gain module inputs the desired input value to the D/A converter which in turn delivers to the oscillator for the generation of a corresponding clock.

Abstract: A charge domain filter (CDF) is provided. The CDF includes a switched-capacitor network (SCN) and a clock generator. An input of the SCN receives an input signal. The SCN samples the input signal according to clock signals with different phases. The clock generator is coupled to the SCN for providing the clock signals. The clock generator adjusts phase differences of the clock signals or pulse widths of the clock signals in accordance with a control signal.