Abstract: A semiconductor memory device is capable of controlling a delay locked loop appropriately based on operation modes, particularly in a fast power-down mode to reduce an amount of current maximumly. The semiconductor memory device includes a delay-locked clock signal generating unit, a mode signal generating unit, and a delay locking control unit. The delay-locked clock signal generating unit performs a delay locking operation on a clock signal, thereby generating a delay-locked clock signal. The mode signal generating unit enables a fast precharge power-down mode signal in a fast precharge power-down mode. The delay locking control unit controls the delay-locked clock signal generating unit to be activated in a predetermined cycle in response to the fast precharge power-down mode signal.

Abstract: A pulse signal output circuit capable of operating stably and a shift register including the pulse signal output circuit are provided. A clock signal is supplied to one of transistors connected to a first output terminal. A power supply potential is applied to one of transistors connected to a second output terminal. Thus, power consumed by discharge and charge of the transistor included in the second output terminal can be reduced. Further, since a potential is supplied from a power source to the second output terminal, sufficient charge capability can be obtained.

Abstract: An object of the present invention is to provide a pulse signal output circuit capable of operating stably and a shift register including the pulse signal output circuit. In an embodiment of the pulse signal output circuit, a transistor has a source terminal or a drain terminal connected to a gate electrode of another transistor having a source terminal or a drain terminal forming an output terminal of the pulse signal output circuit, the channel length of the transistor being longer than the channel length of the other transistor. Thereby, the amount of a leakage current modifying the gate potential of the other transistor can be reduced, and a malfunction of the pulse signal output circuit can be prevented.

Abstract: An object is to provide a pulse signal output circuit capable of operating stably and a shift register including the pulse signal output circuit. A pulse signal output circuit according to one embodiment of the disclosed invention includes first to tenth transistors. The ratio W/L of the channel width W to the channel length L of the first transistor and W/L of the third transistor are each larger than W/L of the sixth transistor. W/L of the fifth transistor is larger than W/L of the sixth transistor. W/L of the fifth transistor is equal to W/L of the seventh transistor. W/L of the third transistor is larger than W/L of the fourth transistor. With such a structure, a pulse signal output circuit capable of operating stably and a shift register including the pulse signal output circuit can be provided.

Abstract: Provided are a technique for high-speed switching between clock signals different in frequency, and a clock-control-signal-generation circuit which serves to generate a control signal for clock switching in a clock selector operable to switch between clock signals including a first clock signal based on first and second clock-stop-permission signals and a clock-resume-permission signal. The clock-control-signal-generation circuit includes: a before-switching clock processing unit; and an after-switching clock processing unit. In each of the before- and after-switching clock processing units, the high-frequency clock processing subunit and the low-frequency clock processing subunit take partial charges of processing of clock signals involved in the switching respectively, whereby the processing is speeded up.

Abstract: A method and apparatus for distributing clock signals throughout an integrated circuit is provided. An embodiment comprises a distribution die which contains either the clock signal distribution network by itself, or the clock signal distribution network in tandem with a clock signal generator. The distribution die is electrically connected through an interface technology, such as microbumps, to route the clock signals to the functional circuits on a separate functional die. Alternatively, the distribution die could be electrically connected to more than one die at a time, using vias through the distribution die to route the clock signals to the different die. This separate distribution die reduces the coupling between lines and also helps to prevent signal skew as the signal moves through the distribution network.

Abstract: Apparatus and methods for providing multi-mode clock signals are disclosed. In some embodiments, a multi-mode driver configured to receive a first clock signal, and to selectively output a different clock signal in response to one or more signals from a controller is provided. The driver can include an H-bridge circuit without substantial increases in the size of the design area. Advantageously, lower jitter and improved impedance matching can be accomplished.

Abstract: A clock generating circuit, including a pulse generating unit to generate a plurality of pulse signals based on a reference clock, the pulse signals each having the same period, a phase difference between the adjacent pulse signals being a first phase difference; and a multi-phase clock generating unit to generate a plurality of multi-phase clocks, a phase difference between the adjacent multi-phase clocks being equal to a second phase difference between pulse signals of a pulse signal pair, based on a plurality of unit-phase clock generating units receiving the pulse signal pairs.

Abstract: Some embodiments include apparatus and methods having an output line, clock nodes to receive clock signals, the clock signals being out of phase with each other, and selector circuits to receive data in parallel. In at least one embodiment, the selector circuits are responsive to the clock signals to transfer the data serially to the output line. Such apparatus and methods can also include a control unit to influence a portion of a signal that represents at least a portion of the data at the output line. Additional apparatus and methods are described.

Abstract: A clock generating circuit generates a high frequency clock having a constant duty and the same period as that of an external clock. A clock generating circuit generates a clock signal (hereinafter “the clock”) used for outputting a data signal to a data pin. The clock generating circuit includes at least a dividing portion and a clock generating portion. A dividing portion divides an internal clock signal (hereinafter “the internal clock”) generated based on an external clock signal (hereinafter “the external clock”) and outputs a plurality of divided clock signals (hereinafter “the divided clocks”). The clock generating portion performs a predetermined logical operations combining the divided clocks to generate the clock having a constant duty and the same period as the external clock.

Abstract: A start-up circuit receives a start-up signal instructing start-up of an equipment mounted with the circuit, and executes a predetermined sequence when start-up is instructed by the start-up signal. An oscillator generates a clock signal. A sequence circuit receives the start-up signal and a clock signal output from the oscillator, measures time by counting the clock signal when the start-up signal transits to a predetermined level, and executes a predetermined event at a predetermined timing. The oscillator operates for a period where the start-up signal is at the predetermined level if the start-up signal is at the predetermined level during the period the power key of the equipment mounted with the circuit is being pushed.

Abstract: A semiconductor device includes a pulse signal generating unit for generating a plurality of pulse signals each of which has a different pulse width from each other, a signal multiplexing unit for outputting one of the plurality of the pulse signals as an enable signal in response to frequencies of external clock signals, and a duty ratio detecting unit for detecting a duty ratio of the external clock signals in response to the enable signal.

Abstract: A frequency jitter generator and a frequency jitter PWM controller are provided for overcoming the shortcoming that a conventional PWM controller reduces the electromagnetic interference issue by means of varying the operating frequency of the PWM controller based on an input voltage, while resulting in the uncertainty of the range of frequency jitter and the difficulty circuit design due to the effect of the input voltage and the load. The frequency jitter generator and PWM controller adjust the range of frequency jitter by using a signal within a fixed voltage range. The invention not only gets rid of the effect of the input voltage and the loading, but also simplifies the circuit design by fixing the range of frequency jitter no greater than a predetermined percentage regardless of the operating frequency of the PWM controller.

Abstract: A master clock generation unit for satellite navigation systems, comprises a plurality of frequency inputs for receiving a respective atomic clock signal, each having a first or a second reference frequency, and a number of frequency converters each having an input connected to one of the frequency inputs and an output. Each of the frequency converters receives an offset frequency (selected according to the first and second reference frequency at the assigned frequency input) from at least one frequency synthesizer, for providing the same intermediate frequency at each of the converter outputs. A switching matrix is connected to each of the converter outputs for selecting one of the intermediate frequencies as a primary clock provided at a first matrix output, and another of the intermediate frequencies as a secondary clock provided at a second matrix output.

Abstract: A high voltage input receiver using low voltage transistors is disclosed. In one embodiment, an input receiver circuit includes a comparator circuit and an inverter circuit. The comparator circuit includes a differential input module for generating a control signal by comparing an external voltage and a reference voltage, and a decision module for generating an inverter input signal based on the control signal. In addition, the reference voltage is used to set dc trip point of the input receiver. Moreover, the input receiver includes one or more stress protection modules to protect key components of the input receiver from exceeding their reliability limits.

Abstract: A system for providing a plurality of synchronous timing signals having period values that are not even multiples of the clock period including a plurality of local edge generators receiving the clock signals, each local generator including local programmable means to record an absolute time at which to generate a timing signal in the current or future period and the means to generate that timing signal at a synchronous even sub-division of the clock period resolution. A separate time value is maintained allowing generated timing signals to be delayed by more than one period. An output delay circuit generates the timing signal responsive to a future time value and a phase offset. The phase offset can be provided using a clock multiplier and serial parallel converter to simplify hardware realizations.

Abstract: A multi-phase correction circuit adjusts the phase relationship among multiple clock signals such that their rising edges are equidistant in time from one another.

Abstract: A clock switching circuit comprises PLL circuits into which external clocks CLKT, CLKB are respectively input, a multiplexer for selecting and outputting either an output PLB of one PLL circuit or an inverted signal of an output PLT of the other PLL circuit, and a clock control circuit for subjecting the multiplexer to switching control on the basis of a Lock determination signal that is asynchronous with CLKB and PLB. When the Lock determination signal is input into the clock control circuit, the clock control circuit switches the output of the multiplexer in synchronization with an offset clock PLQB that is offset from the phase of PLB by a predetermined value.

Abstract: A clock generating circuit, including a pulse generating unit to generate a plurality of pulse signals based on a reference clock, the pulse signals each having the same period, a phase difference between the adjacent pulse signals being a first phase difference; and a multi-phase clock generating unit to generate a plurality of multi-phase clocks, a phase difference between the adjacent multi-phase clocks being equal to a second phase difference between pulse signals of a pulse signal pair, based on a plurality of unit-phase clock generating units receiving the pulse signal pairs.

Abstract: The real number counter subtracts the positive integer C if the count value RC is equal to or larger than 0, or adds (the positive integer B-C) and outputs a Carry if the count value RC is negative. The first integer counter for generating the first clock f1 calculates (the count value IC1+the Carry+the positive integer A). The second integer counter 150 for generating the second clock f2 (f2=f1*G) calculates (the count value IC2+the Carry+the positive integer A+the offset value) at each input clock. The correction circuit outputs the offset value so that the second integer counter counts “the maximum count value*(f2/f1?1)*D” times more than the first integer counter with respect to each cycle D having a synchronization cycle length of the first clock f1 and the second clock f2.

Abstract: A clock generation circuit has two output ends to provide a first clock signal and a second clock signal, in response to first and second input signals, respectively. A charge storage component is used to transfer some charge from the first output end to the charge storage component when the first clock signal is high for a period of time, and to transfer the charge from the charge storage component to the second output end when the second clock signal is low. At a different period of time in the clock cycle, the charge storage component is used to transfer some charge from the second output end to the charge storage component when the second clock signal is high for a period of time, and to transfer the charge from the charge storage component to the first output end when the first clock signal is low.

Abstract: A clock generation circuit has two output ends to provide a first clock signal and a second clock signal, in response to first and second input signals, respectively. A charge storage component is used to transfer some charge from the first output end to the charge storage component when the first clock signal is high for a period of time, and to transfer the charge from the charge storage component to the second output end when the second clock signal is low. At a different period of time in the clock cycle, the charge storage component is used to transfer some charge from the second output end to the charge storage component when the second clock signal is high for a period of time, and to transfer the charge from the charge storage component to the first output end when the first clock signal is low.

Abstract: There are provided, in a clock generator for generating a plurality of output clock signals, an apparatus and method for synchronizing the clock generator to an input reference clock in the presence of a jittery input clock provided to the clock generator from a PLL. The clock generator and the PLL each have a divider with the same ratio. The apparatus includes a synchronizer (205) and a state machine (210). The synchronizer receives the input reference clock and the jittery input clock, and generates there from a synchronized input clock signal with respect to the jittery input clock. The state machine receives the synchronized input clock signal and the jittery input clock, synchronizes with the synchronized input clock signal using the jittery input clock, and abstains from a re-synchronizing operation when the jittery input clock has a jitter of up to a pre-defined maximum number of clock widths.

Abstract: In one embodiment of the present invention, a multiple phase pulse generator includes n stages, where each stage includes a first sub-stage and a second sub-stage. The first sub-stage includes a first memory element and the second sub-stage includes a second memory element. The first memory element of each stage is arranged to be set by the preceding stage. The first sub-stage is arranged to supply a stage output pulse while the first memory element is set. The second memory element is arranged to be set by the stage output pulse. The second sub-stage is arranged to hold the first memory element reset after the stage output pulse while the second memory element is set.

Abstract: Error-free data transfer between mesochronous clock domains can be accomplished by writing data to and reading data from a plurality of data storage elements in coordinated fashion. Write operations are controlled by execution of a state sequence synchronously with the source clock domain, and read operations are controlled by execution of the same state sequence synchronously with the destination clock domain. The states respectively correspond to the data storage elements, and the read and write executions of the state sequence do not simultaneously assume the same state.

Abstract: A tunable multiple frequency source system employing offset signal phasing includes a first frequency source, a phase delay element, and a second frequency source configured to operate concurrently with the first frequency source. The first frequency source includes an input coupled to receive a reference input signal and an output for providing a first frequency source signal. The phase delay includes an input coupled to receive the input reference signal, and an output, the phase delay element operable to apply a predefined phase delay to the input reference signal to produce a phase-delayed input signal. The second frequency source includes an input coupled to receive the phase-delayed input signal and an output for providing a second frequency source signal.

Abstract: An internal clock signal driver circuit includes a delay block that delays a rising clock signal and a falling clock signal, and outputs a delayed rising clock signal and a delayed falling clock signal, a rising DLL clock signal generating block that receives and combines the rising clock signal, the falling clock signal, and the delayed rising clock signal, and outputs a rising DLL clock signal, and a falling DLL clock signal generating block that receives and combines the rising clock signal, the falling clock signal, and the delayed falling clock signal, and outputs a falling DLL clock signal.

Abstract: A semiconductor memory device is capable of controlling a delay locked loop appropriately based on operation modes, particularly in a fast power-down mode to reduce an amount of current maximally. The semiconductor memory device includes a delay-locked clock signal generating unit, a mode signal generating unit, and a delay locking control unit. The delay-locked clock signal generating unit performs a delay locking operation on a clock signal, thereby generating a delay-locked clock signal. The mode signal generating unit enables a fast precharge power-down mode signal in a fast precharge power-down mode. The delay locking control unit controls the delay-locked clock signal generating unit to be activated in a predetermined cycle in response to the fast precharge power-down mode signal.

Abstract: An apparatus and method for multi-phase clock generation are disclosed. One embodiment of the apparatus includes a clock divider generating first and second intermediate signals having edges delayed from first edges of a clock signal having a first frequency. Each of the first and second intermediate signals has a second frequency that is half of the first frequency. The first and second intermediate signals have a phase difference of 180° from each other. The apparatus also includes a first delay element delaying the first intermediate signal by a first delay amount; a second delay element delaying the first intermediate signal by a second delay amount; a third delay element delaying the second intermediate signal by a third delay amount; and a fourth delay element delaying the second intermediate signal by a fourth delay amount. The third delay amount is equal to the first delay amount. The fourth delay amount is equal to the second delay amount.

Abstract: Disclosed are multiphase oscillators comprising a plurality of delay stages serially coupled in a loop by a plurality of nodes, with the loop being folded to provide two concentric rings of delay stages with equal numbers of allocated nodes. A second plurality of negative-resistance elements are provided, each element having a first output coupled to a node on the first concentric ring and a second output coupled to a node on the second concentric ring. Each such output switches between first and second voltage levels, and provides a negative resistance to a signal coupled to it during at least a portion of the transition between voltage levels. The outputs of an element switch to opposite voltage levels. With this construction, a high-voltage pulse propagates around the loop of delay stages, with a low-voltage pulse propagating behind it. Also disclosed are circuits to control the direction of pulse propagation.

Abstract: A multi-phase phase interpolator receives two input clocks to generate several equally spaced output clocks using several phase interpolators. A phase interpolator may include a first circuit branch and a second circuit branch with output nodes that are connected together to provide an output clock. The output clock may be generated at least based on resistor values of the phase interpolator.

Abstract: Apparatus, systems, and methods are disclosed that operate to adjust power received by a clock distribution network at least partially based on operating conditions of an integrated circuit. Additional apparatus, systems, and methods are disclosed.

Abstract: A clock distribution tree for an integrated circuit memory includes a set of data drivers, a corresponding set of input buffers coupled to the data drivers, a first clock distribution tree coupled to the data drivers, and a second clock distribution tree coupled to the input buffers, wherein the first and second clock distribution tree are substantially matched and mirrored distribution trees. The line width of the first clock distribution tree is substantially the same as the line width of the second clock distribution tree. The line spacing of the first clock distribution tree is substantially the same as the line spacing of the second clock distribution tree. Numerous topologies for the first and second clock distribution trees can be accommodated, as long as they are matched and mirrored. Valid times for the integrated circuit memory are maximized and data and clock skew is minimized.

Abstract: A zero-delay clock generator has a phase-locked loop (PLL) that generates a feedback clock and receives a reference clocks. All clocks are differential and have a common-mode voltage. The common-mode voltage of an externally-generated reference clock can vary from the common-mode voltage of the internally-generated feedback clock. Differences in common-mode voltage of the reference clock and feedback clock cause delay variations resulting in static phase offsets of generated clocks. A common-mode sense and equalizer senses the common-mode voltages of the buffered reference and feedback clocks, and generates control voltages. The control voltages adjust the common-mode voltage and delay of differential buffers that receive the reference and feedback clocks. The control voltages adjust the differential buffers to match the common-mode voltages of the buffered reference and feedback clocks. The buffered clocks are then applied to a phase and frequency detector of the PLL.

Abstract: A clock driver is provided. A first driving unit is configured with a plurality of drivers and receives a first clock signal to drive a first pumping clock. A second driving unit is configured with a plurality of drivers and receives a second clock signal to drive a second pumping clock. A charge recycling switch is connected between an output terminal of the first driving unit and an output terminal of the second driving unit. A switch controller selectively transfers an input clock signal of the first or second driving unit to the charge recycling switch in response to the first and second pumping clock signals.

Abstract: A clock distribution tree for an integrated circuit memory includes a set of data drivers, a corresponding set of input buffers coupled to the data drivers, a first clock distribution tree coupled to the data drivers, and a second clock distribution tree coupled to the input buffers, wherein the first and second clock distribution tree are substantially matched and mirrored distribution trees. The line width of the first clock distribution tree is substantially the same as the line width of the second clock distribution tree. The line spacing of the first clock distribution tree is substantially the same as the line spacing of the second clock distribution tree. Numerous topologies for the first and second clock distribution trees can be accommodated, as long as they are matched and mirrored. Valid times for the integrated circuit memory are maximized and data and clock skew is minimized.

Abstract: A counter-controlled delay line includes a main oscillator for delaying edges of an input signal to generate a main clock signal. The main oscillator includes a plurality of gated delay elements connected in a ring. Each gated delay element includes a first control terminal to receive a corresponding load signal, and includes a second control terminal to receive a release signal. The release signal may simultaneously enable and disable state transitions in all delay elements, and the load signals may simultaneously drive an output of each delay element to any selected logic state.

Abstract: When the operating speed of a switched capacitor circuit is accelerated, the timing of the clock signals regulating switched capacitor circuit operation can be disrupted by the effects of variation introduced by the manufacturing process as well as parasitic resistance and parasitic capacitance on signal traces. A control signal generating unit adjusts the timing of the bottom plate sampling period and non-overlapping period of the clock signals supplied to operate the switched capacitor circuit, thus avoiding disrupting the control signal timing and affording a switched capacitor circuit without increasing the area of the logic devices that set the bottom plate sampling period and non-overlapping period.

Abstract: A jitter calculator engine that includes a core effects module, an input/output (I/O) module, and a phase lock loop (PLL) module is provided. The core effects module estimates core jitter caused by noise effects impacting a core clock network. The I/O module estimates I/O input pin switching effects on a clock network input signal. In one embodiment, the I/O module identifies a relative frequency of switching by I/O pins in the circuit design. The PLL module estimates an effect of a PLL on a signal delivered to the PLL from an I/O pin. The PLL module accounts for I/O input pin switching effects and core jitter. The jitter calculator engine may be in communication with a database and the different designs evaluated may be stored in the database so that the database becomes a repository for the different designs and may provide useful information for future designs.

Abstract: A DLL circuit uses a rising edge DLL to align the rising edge of the output data to the system clock and a falling edge DLL to align the falling edge of the output data. The DLL circuit does not use the falling edge of the input clock to provide a reference for the falling edge DLL. The DLL circuit uses the rising edge of a first reference clock (a buffered version of the input clock) to align the rising edge of the output data. An additional DLL is used to generate a precise second reference clock that is delayed by exactly one-half period of the first reference clock to align the falling edge of the output data. Any variation in the duty cycle of the input clock or the input clock buffer does not effect the duty cycle of the output data.

Abstract: Generally, the embodiments presented are directed to circuits and methods for triggering an event at a fraction of a clock cycle. A triggering circuit can comprise two or more input circuits that output an event signal. The event signal is received by one of two or more delay circuits that trigger the event signal at a predetermined phase of the clock cycle by moving the event signal from a first clock domain to another clock domain. By triggering the event at a phase division, the triggering circuit outputs signals at a rate faster than the clock cycle.

Abstract: A data output clock generating circuit for a semiconductor memory apparatus includes a rising data output clock generating unit which combines a rising clock with a signal to be generated in response to a rising output enable signal and a falling clock to generate a rising data output clock, and a falling data output clock generating unit which combines the falling clock with a signal to be generated in response to a falling output enable signal and the rising clock to generate a falling data output clock.

Abstract: A method, apparatus, article of manufacture, and system, the method including, in some embodiments, providing a differential clock ganging structure to receive complementary differential clock signals, the differential clock ganging structure outputting clock ganging output signals, providing a source termination structure for each of the clock ganging output signals, and providing an inductance and capacitance compensation structure to receive an output of the source termination structure and to connect to a terminal interconnect for at least one of the clock ganging output signals.

Abstract: A PWM inverter in which high-surge voltage is not applied across terminals of a switching device thereof is provided by preventing multi-phase simultaneous switching.

Abstract: A start-up circuit receives a start-up signal instructing start-up of an equipment mounted with the circuit, and executes a predetermined sequence when start-up is instructed by the start-up signal. An oscillator generates a clock signal. A sequence circuit receives the start-up signal and a clock signal output from the oscillator, measures time by counting the clock signal when the start-up signal transits to a predetermined level, and executes a predetermined event at a predetermined timing. The oscillator operates for a period where the start-up signal is at the predetermined level if the start-up signal is at the predetermined level during the period the power key of the equipment mounted with the circuit is being pushed.

Abstract: An integrated circuit device which internally generates a plurality of drowsy clock signals having different phases is provided. The integrated circuit device includes a phase synchronizer configured to output a plurality of clock signals having different phases in response to an external clock signal and a drowsy clock signal output unit configured to divide frequencies of the plurality of clock signals by a first factor, align the frequency-divided clock signals so that each consecutive clock signal has a constant phase difference relative to a phase difference of a preceding clock signal, and output the drowsy clock signals having lower frequencies and different phases. The integrated circuit device also includes a feedback unit configured to divide frequency of a clock signal with a phase angle of 0 output by the phase synchronizer by the first factor and output the frequency-divided clock signal having a phase angle of 0 degrees to an input port of the phase synchronizer.

Abstract: A clock generator has a reset circuit and (at least) two dividers, where each divider divides a reference clock signal by a divisor value to generate an output clock signal. The reset circuit generates reset signals for the dividers, where the reset signals are delayed relative to one another by a selected number of reference clock cycles, such that the dividers generate output clock signals having a desired phase offset between them.

Abstract: A communication apparatus includes a radio frequency circuit that operates on a radio frequency signal and a digital processing circuit coupled to the radio frequency circuit. The digital processing circuit includes a first timing circuit that provides timed signals to control timing of system operations during an active mode of operation of the digital processing circuit, and a second timing circuit that provides timing signals to control timing of system operations during an active mode of operation of the radio frequency circuit. In one particular embodiment, at least a portion of the first timing circuit is disabled when the radio frequency circuit is active (receiving and/or transmitting).

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: An apparatus is provided that includes a clock distribution network, a plurality of distributed oscillators provided about the clock distribution network so as to provide clock signals on the clock distribution network and a power control circuit to control power applied to the plurality of distributed oscillators. The power control circuit includes a bandgap device to produce a reference voltage based on a desired power level and a comparing/decision device to receive the reference voltage from the bandgap device and to receive the voltage signal from a source external to the apparatus. The comparing/decision device determines whether the signal received from the power source corresponds to the desired power level.