Abstract: An audio information processing apparatus and method include dividing an audio signal, determining a time period having a power change ratio of an audio signal larger than a first threshold value as an attack candidate, searching the time period of the attack candidate and a time period immediately before the time period of the attack candidate for an attack starting point, correcting a power of an audio signal included in the time period, and determining whether a power change ratio of the audio signal included in the time period is larger than a second threshold value for attack detection which is larger than the first threshold value.

Abstract: Audio cables used in deploying audio equipment are typically selected to minimize signal transmission losses and may be chosen based on a distance between, and terminations of, an amplifier system and a loudspeaker system. Since this is usually unknown prior to deployment, multiple audio cables with different sizes and terminations and a variety of electrical extension cords to connect to a power supply line are transported. A loudspeaker adapter for the loudspeaker system and an amplifier adapter for the amplifier system can be used to interconnect the two systems via electrical extension cords. This precludes the need for transporting a large number of audio cables, and allows for interconnecting the loudspeaker and the amplifier systems without prior knowledge of the distance between the systems. Safety hazards and component damage can also be minimized by not connecting a hot terminal in the AC connectors of the loudspeaker and amplifier adapters.

Abstract: When an output voltage from the amplifying circuit includes a positive DC voltage, an electric current continuously flows in a power source voltage, a load, and a reference voltage in this order. As a result, the reference voltage increases so as to be a first threshold voltage or more . The detecting section detects that the reference voltage is the first threshold voltage or more. When the output voltage from the amplifying circuit includes a negative DC voltage, an electric current continuously flows in the reference voltage, the load, a grounding potential in this order. As a result, the reference voltage reduces so as to be a second threshold voltage or less. The detecting section detects that the reference voltage is the second threshold voltage or less.

Abstract: A method and system for removing noise due to bias electric power (MIC_Bias) or Time Division Multiple Access (TDMA) noise are provided. The system includes an interface with a microphone contact, for connecting to an accessory, an Analog-to-Digital (AD) converter for converting an analog voltage level, input via the microphone contact, into a digital voltage level, an audio processing unit for processing an audio signal input via the microphone contact, a switch for at least one of connecting and disconnecting the microphone contact and the AD converter, and a controller. The controller compares the digital voltage level with voltage levels stored in a look up table. The controller identifies a type of accessory connected to the interface. The controller also switches off the switch to prevent noise from being introduced into the audio signal via a wire connecting the microphone contact and the AD converter.

Abstract: A circuit of reducing a pop-up noise in a digital amplifier includes a switch unit and a switch signal generator. The switch unit is coupled in parallel to an output load between an output node of the digital amplifier and a reference node. The switch unit controls a current flowing through the output load by forming a conduction path between the output node and the reference node in response to a switch signal. The switch signal generator generates the switch signal in response to a switch control signal indicating a power-on or a power-off. The pop-up noise is reduced by the conduction path that is formed when the digital amplifier is powered on or off.

Abstract: An audio signal processing apparatus for outputting an input digital audio signal as a positive phase PWM signal and a negative phase PWM signal. The resolution of the input digital audio signal is converted to a low resolution and noise shaping is performed to generate a positive phase digital signal (REF_P) and a negative phase digital signal (REF_N). Both signal patterns are compared at a buffer and pattern comparator section when muting. If the signal patterns match, a selector outputs a set value having 50% duty instead of the digital signals to optimize timing for switching to 50% duty when muting.

Abstract: An automated noise reduction circuit is configured to find an audio output with the lowest voltage level associated with undesirable noise. The circuit may include a plurality of audio input ports, ground isolation devices, electronic switches and a microprocessor. The microprocessor may be configured to toggle the ground isolation devices on and off, sample voltage at an output of the ground loop isolation transformers when the ground isolation devices are on and off, and switch the ground isolation devices to a position that produces a lowest voltage output based on a comparison of sampled voltage that is analyzed by a set of algorithms programmed into the microprocessor and that has been sampled from the output of the ground isolation devices for each of the multiple input ports.

Abstract: The invention provides a microphone circuit. In one embodiment, the microphone circuit comprises a transducer, a biasing resistor, a pre-amplifier, and a switch circuit. The transducer is coupled between a ground and a first node for converting a sound into a voltage signal output to the first node. The biasing resistor is coupled between the ground and the first node. The pre-amplifier is biased with a biasing voltage and coupled between the first node and a second node, and amplifies the voltage signal to obtain an output signal at the second node. The switch circuit is coupled between the first node and the ground, couples the first node to the ground when the microphone circuit is reset, and decouples the first node from the ground after a voltage status of the microphone circuit is stable, thus clamping a voltage of the first node to the ground to prevent generation of a popping noise when the microphone circuit is reset.

Abstract: A microphone system has a primary microphone for producing a primary signal, a secondary microphone for producing a secondary signal, and a selector operatively coupled with both the primary microphone and the secondary microphone. The system also has an output for delivering an output audible signal principally produced by one of the to microphones. The selector selectively permits either 1) at least a portion of the primary signal and/or 2) at least a portion of the secondary signal to be forwarded to the output as a function of the noise in the primary signal.

Abstract: System and method for muting an output terminal of an electronic device. In one embodiment, the process for can include receiving one or more signals received by the controller over the first terminal, detecting a mute control signal from the controller and controlling the state of a switch coupled to the output terminal to ground the output terminal based on detecting the mute control signal.

Abstract: A modulated gain audio control and zipper noise suppression techniques provide reduction in audible artifacts caused by discrete-valued gain changes. The gain of a signal is controlled by modulating between multiple gain values for corresponding time durations, so that a resulting average gain is controlled according to the average of the multiple gain values as weighted by their corresponding time durations. The modulation frequency is above the bandwidth of the signal. Transitions between gain levels are performed by changing the relative proportion of the durations to slowly change the gain according to a transition profile, which may be linear or non-linear. The modulation employed may be pulse-width modulation, or another modulation pattern such as a delta-sigma modulation pattern.

Abstract: An audio amplifier includes a timing control circuit, an amplifying circuit, and a bias control circuit. The timing control circuit generates a first power down signal and a second power down signal, in which the first power down signal is asserted before the second power down signal is asserted. The amplifying circuit receives a bias voltage to amplify an audio signal and is deactivated when the first power down signal is asserted. The bias control circuit provides the bias voltage for the amplifying circuit and is deactivated when the second power down signal is asserted.

Abstract: A circuit and method of switching an output of a single preamplifier to or from multiple amplifier output stages. The preamplifier output is switched between multiple audio amplifier output stages without degrading the performance of the output signal. A switching circuit selectively couples the preamplifier output to an amplifier output stage and also couples a feedback loop between the selected amplifier output stage and the preamplifier stage.

Abstract: When an output voltage from the amplifying circuit includes a positive DC voltage, an electric current continuously flows in a power source voltage, a load, and a reference voltage in this order. As a result, the reference voltage increases so as to be a first threshold voltage or more . The detecting section detects that the reference voltage is the first threshold voltage or more. When the output voltage from the amplifying circuit includes a negative DC voltage, an electric current continuously flows in the reference voltage, the load, a grounding potential in this order. As a result, the reference voltage reduces so as to be a second threshold voltage or less. The detecting section detects that the reference voltage is the second threshold voltage or less.

Abstract: The present invention discloses a circuit with three-stage of power-on sequence used for suppressing the pop noise in audio system. It mainly comprises a first resistor (R1); a capacitor (Cout); a first switch (SW1); a second switch (SW2); a soft start device; a first feedback amplifier; and a second feedback amplifier. By using the three-stage of power-on sequence, the present invention can effectively suppress the pop noise when the audio driver is power on.

Abstract: An amplification circuit for driving an audio signal diffuser that includes a generation circuit of a first pre-charging signal, the generation circuit including an amplifier provided with an input terminal for receiving the first pre-charging signal and provided with an output terminal for providing a second pre-charging signal as a function of the first pre-charging signal, and a decoupling capacitor of the amplifier from the diffuser, the capacitor connected to the output terminal for charging by the second pre-charging signal.

Abstract: A surge protection circuit acquires a surge signal from a left channel (LC) signal line and a right channel (RC) signal line. After the surge signal being transmitted on the LC signal line and the RC signal line is removed, an audio signal outputted from a signal input device is transmitted to an audio output device via the LC signal line and the RC signal line.

Abstract: An apparatus for reducing digital audio output noise includes: a signal processing unit configured to process digital audio data to output to a speaker; a switching unit configured to mute the speaker; and a control unit configured to monitor the signal processing unit to determine whether a current state is a mute state or not, and control the switching unit according to the determination result.

Abstract: An amplifier power-down apparatus for suppressing transient signals in a circuit, for example an audio circuit, comprising a reference voltage generator circuit for generating a reference voltage. The reference voltage generator circuit comprises a capacitor for maintaining the reference voltage at a desired level. The amplifier power-down apparatus comprises a discharge control circuit for controlling the operation of the reference voltage generator circuit during power-down. The discharge control circuit comprises an amplifier with a positive feedback path for controlling a current flow from the capacitor during power-down.

Abstract: In an audio processing system and method, pull-up circuits and a capacitor circuit are used to cause gradual change in voltage levels of audio signals which would otherwise change abruptly due to high-speed switching when switching from a first audio signal to a second audio signal at a user's command. As a result, pop noise is prevented.

Abstract: An amplifier start-up apparatus for reducing transient signals in a circuit, for example an audio circuit, comprising a reference voltage generator circuit for generating a reference voltage. The reference voltage generator circuit comprises a capacitor for maintaining the reference voltage at a desired level. The amplifier start-up apparatus comprises a control circuit for controlling the operation of the reference voltage generator circuit during power-up. The control circuit comprises an amplifier with a positive feedback path for controlling a current flow to the capacitor.

Abstract: Disclosed herein are conferencing products implementing an acoustic echo cancellation system that utilizes converging coefficients and a detector of turn-off and/or turn-on events of push-to-talk microphones, and, further, that mitigates against divergence and/or drift of coefficients and other variables of an echo canceller. A push-to-talk detector may be used that includes a high-pass filter, a transient detector, or an adjustable high-pass filter. An echo canceller may be disabled as to a push-to-talk microphone that has been turned off.

Abstract: An anti-pop circuit is coupled with a sound outputting device to prevent a “pop” sound form being mixed into a sound signal. The anti-pop circuit includes a control signal generator and a fist diode. The control signal generator generates a control signal with a high level state and a low level state. The first diode couples with the sound outputting device. The sound signal is transferred to the first diode when said first diode is in a forward bias state, and the sound signal is outputted from an output end of the sound outputting device when the first diode is in a reverse bias state.

Abstract: A pop noise suppression apparatus for eliminating popping noise generated upon initiation or shutdown of an audio output circuit comprises a switch component and a control circuit. The switch component allows the audio output circuit to provide audio through the output of the audio output circuit. The control circuit provides a mute signal for a first period of time in to response initiation or shutdown of the audio circuit. The control circuit comprises a capacitor to be charged upon initiation of the audio output circuit or to be discharged upon shutdown of the audio output circuit. A length of the first period of time during which the mute signal is provided depends on a second period of time to charge or discharge the capacitor.

Abstract: A method and an apparatus for designing a sound compensation filter of a portable terminal are provided. The method includes synchronizing a signal input through a microphone of the system and a test signal, estimating a loss interval of the synchronized signal, compensating for a frame signal delayed by a signal loss in a time axis when the signal loss of the estimated loss interval is greater than a threshold and restoring the loss interval of the signal.

Abstract: A sound collection apparatus includes a target sound collection unit that collects a sound including a target sound and outputs a collected-sound signal, a non-target sound collection unit, provided at positions different from each other, forms dead zones of sensitivity in a direction of the target sound source so as to collect a sound outside the dead zones and outputs a collected-sound signal. A sensitivity suppression unit generates a sensitivity suppression signal for suppressing a sound collection sensitivity in an overlap region in which dead zones overlap, as compared to a region surrounding the overlap region, by subjecting, to a predetermined signal processing, the collected-sound signal outputted by the non-target sound collection unit. An extraction unit removes, from the collected-sound signal, the sensitivity suppression signal generated, so as to extract a signal of a sound generated in the overlap region in which the dead zones overlap.

Abstract: An audio output circuit includes a port attenuation circuit, which is configured to convert an abrupt dc voltage offset transition between a pair of audio signals received in sequence at an input thereof into a more gradual transition. This conversion is achieved by performing, in sequence, a ramp-to-mute operation on a first of the pair of audio signals and a ramp-from-mute operation on a second of the pair of audio signals. The ramp-to-mute operation includes ramping an output of the audio output circuit from a dc voltage offset associated with the first of the pair of audio signals to a reference dc voltage offset. The ramp-from-mute operation includes ramping the output of the audio output circuit from the reference dc voltage offset to a dc voltage offset associated with the second of the pair of audio signals. These ramping operations may be performed using voltage steps having uniform step size.

Abstract: An pop noise eliminating circuit includes a power source, a grounding terminal, a speaker, an audio amplifier that has two opposite ends respectively connected with the power source and the first end of the speaker, a delay unit that has one end electrically connected with the power source, a first power control switch that has a control end electrically connected with the delay unit, a first conduction end electrically connected with the other end of the speaker, and a second power control switch that has a control end electrically connected with the delay unit, a first conduction end electrically connected with the grounding terminal, and a second conduction end electrically connected with a second conduction end of the first power control switch.

Abstract: An audio output device and method capable of preventing generation of pop noise by a relatively simple and small-sized circuit configuration and control timing. A D/A converter converts a digital audio signal to an analog audio signal. A non-inverting amplifier amplifies the analog audio signal. A signal output from the non-inverting amplifier is amplified by inverting amplifiers of two stages with a first timing. A signal output from an inverting amplifier is input to a speaker amplifier by a switch. The output signal of the inverting amplifier is output to a speaker with a second timing subsequent to the first timing. The output signal of the inverting amplifier is amplified by the speaker amplifier and output to the speaker. With a third timing subsequent to the second timing, the output of each of the inverting amplifiers is stopped and the output of the speaker amplifier is stopped.

Abstract: The invention concerns a method and signal conversion device for avoiding undesirable noise in the start up of an amplifying device, as well as to an amplifying device including such a signal conversion device. The signal conversion device (12) comprises a variable gain providing unit (Q3, Q4, Q5, Q6), a voltage to current converter (Q1, Q2, R1, R2), a variable gain control unit (22) controlling the variable gain of the variable gain providing unit, and a bias current control unit (20) for controlling a first biasing current (IB1) of the voltage to current converter, for avoiding DC offset originating noise as well as noise originating from components of the signal conversion device.

Abstract: A plurality of main amplifiers amplifies input audio signals with an adjustable gain. A first selector selects any of the input audio signals. An auxiliary amplifier receives an output of the first selector and amplifies this output with an adjustable gain. A second selector receives n outputs from the main amplifiers and selects any of the outputs. A soft switching circuit receives an output of the second selector at a first input terminal, receives an output of the auxiliary amplifier at a second input terminal, and makes the output transition gradually from one of the input terminals to the other of the input terminals. Output switches are respectively provided for the main amplifiers, an output of a corresponding main amplifier is received at a first input terminal, an output of the soft switching circuit is received at a second input terminal, and one of the outputs is selected to be outputted.

Abstract: A speaker array and microphone arrays positioned on both sides of the speaker array are provided. A plurality of focal points each serving as a position of a talker are set in front of the microphone arrays respectively symmetrically with respect to a centerline of the speaker array, and a bundle of sound collecting beams is output toward the focal points. Difference values between sound collecting beams directed toward the focal points that are symmetrical with respect to the centerline are calculated to cancel sound components that detour from the speaker array to microphones. Then, it is estimated based on totals of squares of peak values of the difference values for a particular time period that the position of the talker is close to which one of the focal points, and the position of the talker is decided by comparing the totals of the squares of the peak values of the sound collecting beams directed to the focal points that are symmetrical mutually.

Abstract: The present invention discloses a multi-level output signal converter, which is connected to an audio amplifier. The audio amplifier comprises a comparing/measuring device, an encoder and an output unit. The multi-level output signal converter comprises a timing processing unit and a multi-level converter. The timing processing unit is connected to the comparing/measuring device and the encoder. The timing processing unit includes a plurality of flip-flops and a timing summing element. The flip-flop receives a first signal from the comparing/measuring device and outputs the first signal to the timing summing element. The encoder converts the first signal into a second signal. The multi-level converter is connected to the encoder and the output unit. The encoder transmits the second signal to the multi-level converter, and the multi-level converter thus outputs a third signal to the output unit.

Abstract: A multi-channel audio playback apparatus including a channel interface, a first switching amplifier and a second switching amplifier is provided. The channel interface is used to receive multi-channel digital data and generate first channel digital data and second channel digital data. The first switching amplifier is used to convert the first channel digital data into a first pulse width modulation (PWM) signal according to a first reference signal with a first frequency. The second switching amplifier is used to convert the second channel digital data into a second PWM signal according to a second reference signal with a second frequency. The second frequency is different from the first frequency.

Abstract: An audio reproducing apparatus includes a power supply, an amplifier, a speaker, and a controller. The power supply is for supplying a voltage. The amplifier is for receiving the voltage and audio signals, amplifying the audio signals, and outputting amplified audio signals. The speaker is for reproducing sound after receiving the amplified audio signals. The controller is for receiving the voltage and generating a control signal to enable the amplifier. The controller includes a generator and a delay unit. The generator is for receiving the voltage and generating the control signal. The delay unit is for delaying the time of transferring the voltage from the power supply to the generator.

Abstract: A muting circuit comprising: a DC offset eliminating unit including an HPF (High Pass Filter) constituted by a first operational amplifier to eliminate a DC offset component of an AC input signal, the DC offset eliminating unit being configured to output an output signal obtained by eliminating the DC offset component of the AC input signal; a muting signal generating unit including a second operational amplifier configured to generate a second DC offset identical in level to a first DC offset at the first operational amplifier, the muting signal generating unit being configured to output a muting signal indicative of the second DC offset by fixing input to the second operational amplifier at a predetermined DC level; and a selecting unit configured to select and output the output signal when muting is not executed, and to select and output the muting signal when muting is executed.

Abstract: A circuit for eliminating pop sounds at power on and off by a moderate waveform, which includes a switch, a feedback network, an operational amplifier and an output network. When power-on, a first input terminal of the switch is connected to a low voltage, and an output terminal of the output network provides an operating DC bias which is gradually increased. When power-off, the first input terminal of the switch is connected to a reference voltage, and the output terminal of the output network provides an operating DC bias which is gradually reduced.

Abstract: When an abnormality occurs in a supply circuit and its output is decreased, a protect circuit detects the abnormality and outputs a protect signal to an audio circuit. The audio circuit upon detection of the protect signal stops outputting audio so that outputting of an audio noise due to a deficiency in the supplied voltage is prevented. Meanwhile, when no abnormality occurs in the supply circuit, a microcomputer controls the audio circuit by supplying it with such a signal as to allow it to output an audio, or to increase the audio volume, or with a mute signal.

Abstract: A circuit for eliminating noise includes a sound card (30) with an audio signal output, a power supply (10) for providing working voltage to the sound card, a first transistor (Q1), a second transistor (Q2), and a third transistor (Q3). The power supply has a power good pin, a PSON# pin, and a standby voltage pin. During powering on time of the sound card, the power good pin is at low level and the second transistor is therefore turned on to ground the audio signal output so as to eliminate turn-on noise. During powering down time of the sound card, the PSON# pin turns from low to high level to turn on the third transistor before the audio power for providing working voltage to the sound card is powered down, thus the first transistor turns off, and the second transistor turns on to ground the audio signal output of the sound card so as to eliminate turn-off noise.

Abstract: A de-pop circuit adaptable to an audio circuit is disclosed. A high-pass filter generates a high-pass output signal according to an output signal of the audio circuit. A blockage circuit receives the high-pass output signal and a control signal, and generates an enable signal to activate the audio circuit according to the control signal and the high-pass output signal.

Abstract: A noise processing device and its method are provided for a video/audio system having a high definition multimedia interface (HDMI). The noise processing device includes a detecting unit, a signal generating unit, and a decision unit. The noise processing method includes using the detecting unit to monitor a variation related to an audio signal and generate a detecting signal accordingly; using the signal generating unit to produce an adjustment signal according to the detecting signal; and using the decision unit to produce an output audio signal according to the audio signal and the adjustment signal. Another embodiment of the noise processing device includes a compensation tracking unit having a control unit. The compensation tracking unit produces an output audio signal according to a difference between the output audio signal itself and the audio signal and a gain of the control unit.

Abstract: The present invention provides improvements to prior art audio codecs that generate a stereo-illusion through post-processing of a received mono signal. These improvements are accomplished by extraction of stereo-image describing parameters at the encoder side, which are transmitted and subsequently used for control of a stereo generator at the decoder side. Furthermore, the invention bridges the gap between simple pseudo-stereo methods, and current methods of true stereo-coding, by using a new form of parametric stereo coding. A stereo-balance parameter is introduced, which enables more advanced stereo modes, and in addition forms the basis of a new method of stereo-coding of spectral envelopes, of particular use in systems where guided HFR (High Frequency Reconstruction) is employed. As a special case, the application of this stereo-coding scheme in scalable HFR-based codecs is described.

Abstract: An n-channel integrated circuit device (n is an integer of 1 or greater) for muting an audio signal includes a control circuit configured to generate a control signal and a delayed control signal, a charging and discharging circuit configured to charge and discharge a time constant control terminal according to the control signal and the delayed control signal, an N-th voltage-to-current converting circuit (N is an integer from 1 to n) configured to generate a (2N?1)-th current corresponding to a voltage on the time constant control terminal and a (2N)-th current corresponding to an intermediate voltage, a (2N?1)-th mirror circuit configured to copy the (2N?1)-th current to generate (4N?3)-th and (4N?2)-th intermediate currents, a (2N)-th mirror circuit configured to copy the (2N)-th current to generate (4N?1)-th and (4N)-th intermediate currents, a (2N?1)-th selecting and combining circuit configured to combine a (2N?1)-th mute control current using the (4N?3)-th intermediate current and the (4N?1)-th interm

Abstract: A signal amplifying circuit is provided. The signal amplifying circuit includes a signal amplifier and a control circuit. The control circuit includes a compare unit and a register unit. The compare unit compares an input signal of the signal amplifier with a reference signal to generate a compare signal. The register unit receives and registers a control signal to be transmitted to the signal amplifier, and provides a registered signal to the signal amplifier according to the registered control signal when the compare signal is changed.

Abstract: An audio output apparatus includes: an audio codec outputting an analog audio signal corresponding to a digital audio signal from a system controller; a switch unit having a first end coupled to the audio codec through a capacitor, and a grounded second end; and a switch controller triggered by a trigger signal to output a control signal to a control end of the switch unit such that the switch unit couples the capacitor to ground in response to the control signal. The trigger signal is generated by one of the system controller, the audio codec, and a power circuit supplying electric power to the system controller, the audio codec and the switch controller upon occurrence of a condition associated with pop noise, and is outputted to the switch controller before the pop noise is generated, such that the pop noise is conducted to ground via the switch unit.

Abstract: An external amplifier and a noise removing method thereof are disclosed. When an audio output inputted to the external amplifier is changed from a first mode to a second mode, channel status information is set to the second mode and no data of the audio output is outputted in the second mode for a predetermined period of time. Therefore, it is possible to remove noise that is generated in the external amplifier when the audio output mode is changed, thereby preventing speaker damage.

Abstract: A charge/discharge control circuit for controlling current through an input/output audio device includes a first voltage reference; a second voltage reference and a waveform generation circuit responsive to the first and second voltage references for generating a multi-stage waveform profile which is approximately an inaudible waveform for suppressing audible artifacts in the input/output device.

Abstract: A pop sound prevention module and a speaker apparatus thereof are provided. The pop sound prevention module is used for preventing the speaker apparatus generating a pop sound when a power shuts down. The speaker apparatus includes an audio amplifier, an audio processor, the pop sound prevention module, and a loudspeaker. The audio processor is coupled to a first operation voltage. The audio amplifier is coupled to a second operation voltage. When the power shuts down, the pop sound prevention module outputs a mute control signal to the audio amplifier according to voltage difference between the first operation voltage and the second operation voltage. According to the mute control signal, the audio amplifier prevents the loudspeaker from generating a pop sound.

Abstract: An audio apparatus receives a supply voltage from a power source and is powered on. The audio apparatus includes a control unit, an amplifier, and a mute circuit. The control unit provides an audio signal. The amplifier amplifies the audio signal and drives a speaker to reproduce sound according to the amplified audio signal. The mute circuit generates a mute signal when initially receiving the supply voltage from the power source. The amplifier stops driving the speaker to reproduce sound according to the mute signal.

Abstract: The potential of a smoothing capacitor for a speaker is smoothly changed by controlling the potential with use of a PWM signal and switching between outputting the PWM signal and an actual audio signal, thereby suppressing a pop sound. The scale of circuitry is reduced and cost is lowered by implementing a PWM circuit in a one-chip microcontroller. Noise is eliminated by outputting a pulse that has been divided in the PWM signal generation stage.