A method, applied in a driving circuit including a bidirectional circuit coupled between a voltage source and a load, includes receiving a feedback signal from the load and an input signal; generating a plurality of pulse width modulation (PWM) signals according to the input signal and the feedback signal; driving the load by the bidirectional circuit according to the plurality of PWM signals such that the input signal and the feedback signal are substantially proportional to each other. The input signal is a time varying signal. The step of generating a PWM signal among the plurality of PWM signals according to the input signal and the feedback signal includes determining a difference according to the input signal and the feedback signal; and generating the PWM signal with a pulse width. The pulse width is determined according to the difference.

An amplifier for headphones including a current digital-to-analog converter (DAC) configured to output a current based on a digital audio input signal, an output electrically connected to a speaker and configured to output an output signal to the speaker, and a pulse width modulation (PWM) loop configured to receive an error signal, the error signal based on a difference between the current from the current DAC and a current of the output signal, and generate the output signal based on the error signal. The PWM loop includes an analog-to-digital converter (ADC) configured to receive an analog signal based on the current from the current DAC and output a digital signal representing the analog signal, and an encoder configured to receive the digital signal and output a pulse having a width based on the analog signal.

A device includes a sensor configured to output an analog sensor signal, an analog-to-digital converter circuit configured to convert the analog sensor signal into a sigma-delta-modulated digital signal having a bit width of n bits, and a pulse width modulator configured to generate a pulse-width-modulated signal based on the sigma-delta-modulated digital signal.

A signal processing apparatus is provided which can suppress external noise without degrading an audio characteristic. Provided is a signal processing apparatus including: an A/D converter configured to output a digital signal having a predetermined sampling frequency and quantization bit number a, the A/D converter including a first delta sigma modulator that performs a first delta sigma modulation process on an input analog signal; a filter unit configured to pass an output of the A/D converter through a digital filter provided with a predetermined filter characteristic and output a digital signal having the sampling frequency and a quantization bit number b; a second delta sigma modulator configured to perform a second delta sigma modulation process on an output of the filter unit and output a digital signal having the sampling frequency and the quantization bit number a; and an addition unit configured to add an output of the second delta sigma modulator and an input digital signal having the sampling frequency and the quantization bit number.

An image processing apparatus is applied to a display and includes a sampling unit, a comparing unit, a determining unit and an operating unit. The sampling unit is configured to receive a pulse-width modulation (PWM) signal and sample the PWM signal to output a current image. The comparing unit is coupled to the sampling unit and configured to compare the current image with a previous image to generate a comparison result, wherein the previous image is prior to the current image. The determining unit is coupled to the comparing unit and configured to determine whether the current image is the same with the previous image according to the comparison result and a threshold value. If a determination result of the determining unit is YES, the operating unit stops its operation.

A method of controlling a resolution of digital pulse width modulation is applied to a digital pulse width modulation generator. The method is to divide a value of a first duty clock by a value of a first pulse width modulation period clock to generate a first resolution. And then, if it is confirmed that a modulation command has been received, a second resolution is generated, and if it is confirmed that the modulation command is not received, a third resolution is generated. The second resolution is greater than the first resolution, and the second resolution is less than the third resolution.

A delta-sigma modulator may include a loop filter having a loop filter input configured to receive an input signal and generate an intermediate signal responsive to the input signal and a near-zero asymmetric quantizer configured to quantize the intermediate signal into a quantized output signal which is fed back as an input to the loop filter such that the quantized output signal has a plurality of quantization levels, wherein the plurality of quantization levels are asymmetric to zero.

An amplifier for headphones including a current digital-to-analog converter (DAC) configured to output a current based on a digital audio input signal, an output electrically connected to a speaker and configured to output an output signal to the speaker, and a pulse width modulation (PWM) loop configured to receive an error signal, the error signal based on a difference between the current from the current DAC and a current of the output signal, and generate the output signal based on the error signal. The PWM loop includes an analog-to-digital converter (ADC) configured to receive an analog signal based on the current from the current DAC and output a digital signal representing the analog signal, and an encoder configured to receive the digital signal and output a pulse having a width based on the analog signal.

A delta-sigma modulator may include a loop filter having a loop filter input configured to receive an input signal and generate an intermediate signal responsive to the input signal and a near-zero asymmetric quantizer configured to quantize the intermediate signal into a quantized output signal which is fed back as an input to the loop filter such that the quantized output signal has a plurality of quantization levels, wherein the plurality of quantization levels are asymmetric to zero.

An image processing apparatus and an image processing method applied to a display are disclosed. The image processing apparatus includes a sampling unit, a comparing unit, a determining unit and an operating unit. The sampling unit is configured to receive a pulse-width modulation (PWM) signal and sample the PWM signal to output a current image. The comparing unit is coupled to the sampling unit and configured to compare the current image with a previous image to generate a comparison result, wherein the previous image is prior to the current image. The determining unit is coupled to the comparing unit and configured to determine whether the current image is the same with the previous image according to the comparison result and a threshold value. If a determination result of the determining unit is YES, the operating unit stops its operation.