Abstract: A digital-to-analog converter (DAC) includes a plurality of reference modules, an output capacitor configured to output the analog voltage, and a sharing switch coupled between the output capacitor and the reference modules. The reference modules are mutually connected in parallel. Each reference module includes a reference capacitor and a reference switch connected in series. A plurality of reference capacitances of the reference capacitors are substantially identical. The reference switches are controlled by a plurality of control signals. The control signals are corresponding to a control code. The DAC produces an analog voltage according to the control code. An analog difference, between a first analog voltage corresponding to a first control code and a second analog voltage corresponding to a second control code, monotonically increases or monotonically decreases as a first value corresponding to the first control code increases. The first control code is consecutive to the second control code.

Abstract: 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.

Abstract: A digital-to-analog converter (DAC) includes a plurality of reference modules, an output capacitor configured to output the analog voltage, and a sharing switch coupled between the output capacitor and the reference modules. The reference modules are mutually connected in parallel. Each reference module includes a reference capacitor and a reference switch connected in series. A plurality of reference capacitances of the reference capacitors are substantially identical. The reference switches are controlled by a plurality of control signals. The control signals are corresponding to a control code. The DAC produces an analog voltage according to the control code. An analog difference, between a first analog voltage corresponding to a first control code and a second analog voltage corresponding to a second control code, monotonically increases or monotonically decreases as a first value corresponding to the first control code increases. The first control code is consecutive to the second control code.

Abstract: A bidirectional charging and discharging circuit is coupled between a voltage source and a capacitive load and configured to drive the capacitive load. The bidirectional charging and discharging circuit includes a first switch, comprising a first terminal coupled to the voltage source; a second switch, comprising a first terminal coupled to a second terminal of the first switch, and a second terminal coupled to a ground; an inductor, comprising a first terminal coupled to the second terminal of the first switch and the first terminal of the second switch; a third switch, comprising a first terminal coupled to a second terminal of the inductor, and a second terminal coupled to a first terminal of the capacitive load; and a fourth switch, comprising a first terminal coupled to the second terminal of the inductor and the first terminal of the third switch, and a second terminal coupled to a ground.

Abstract: An acoustic transducer is disposed within a wearable sound device or to be disposed within the wearable sound device. The acoustic transducer includes a first anchor structure and a first flap. The first flap includes a first end and a second end. The first end is anchored by the first anchor structure, and the second end is configured to perform a first up-and-down movement to form a vent temporarily. The first flap partitions a space into a first volume to be connected to an ear canal and a second volume to be connected to an ambient of the wearable sound device. The ear canal and the ambient are connected via the vent temporarily opened.

Abstract: A crossover circuit, disposed within a sound producing device including a first sound producing cell driven by a first driving signal and a second sound producing cell driven by a second driving signal, includes a first filter receiving an input signal at an input terminal of the first filter, a first subtraction circuit, and a second filter coupled between the output terminal of the first filter and the second input terminal of the first subtraction circuit. A first input terminal of the first subtraction circuit is coupled to the input terminal of the first filter; a second input terminal of the first subtraction circuit is coupled to an output terminal of the first filter. The crossover circuit produces the first driving signal and the second driving signal according to a first output signal of the first subtraction circuit and a second output signal of the first filter respectively.

Abstract: A sound producing package structure includes a plurality of chips disposed within a cavity. The chips includes a first chip and a second chip, the first chip includes a first sound producing membrane and a first actuator attached to the first sound producing membrane, and a second chip includes a second sound producing membrane and a second actuator attached to the second sound producing membrane. The first sound producing membrane and the second sound producing membrane are actuated toward a center of the cavity in a synchronous fashion so as to produce a sound pressure.

Abstract: A system, disposed within a wearable hearing device, includes a sound producing device (SPD) driven by a driving voltage, a first sound sensing device, and a subtraction circuit. The first sound sensing device is configured to sense a combined sound pressure produced at least by the SPD and generate a sensed signal accordingly. The subtraction circuit has a first input terminal, a second input terminal, and a first output terminal. The first input terminal is coupled to the first sound sensing device, and the first output terminal is coupled to the SPD. A first phase delay between the driving voltage and the sensed signal is less than 60°.

Abstract: A sound producing device includes at least one air pulse generating element. Each of the at least one air pulse generating element includes a membrane, a first air chamber and at least one opening, wherein a chamber pressure exists in the first air chamber. The membrane is actuated to change the chamber pressure of the first air chamber to generate a plurality of air pulses, the air pulses are propagated through the at least one opening, the air pulses produce a non-zero offset in terms of sound pressure level, and the non-zero offset is a deviation from a pressure value of an ambient pressure outside the sound producing device.

Abstract: A sound producing device includes a first sound producing cell, driven by a first driving signal and configured to produce a first acoustic sound on a first audio band, and a second sound producing cell, driven by a second driving signal and configured to produce a second acoustic sound on a second audio band different from the first audio band. A first membrane of the first sound producing cell and a second membrane of the second sound producing cell are Micro Electro Mechanical System fabricated membranes. The first audio band is upper bounded by a first maximum frequency; the second audio band is upper bounded by a second maximum frequency. A first resonance frequency of the first membrane is higher than the first maximum frequency of the first driving signal. A second resonance frequency of the second membrane is higher than the second maximum frequency of the second driving signal.

Abstract: A sound producing package structure includes a shell and a chip. The shell includes a top structure, a bottom structure and a sidewall structure. The chip is disposed inside the shell and configured to produce an acoustic wave, wherein the chip includes a thin film structure and an actuator configured to actuate the thin film structure, and the thin film structure is substantially parallel to the top structure and the bottom structure. A first opening is formed on the sidewall structure, and the acoustic wave propagates outwards through the first opening.

Abstract: A method applied in a driving circuit is disclosed. The driving circuit is coupled between a voltage source and a load and configured to drive the load. The method includes: forming, by the driving circuit, a first current from the voltage source to the load; and forming, by the driving circuit, a second current from the load back to the voltage source.

Abstract: A sound producing device includes a base and at least one chip disposed on the base. The chip includes at least one membrane and at least one actuator. The membrane includes a coupling plate and at least one spring structure connected to the coupling plate. The actuator is configured to receive a driving signal corresponding to an input audio signal to actuate the membrane, and the input audio signal and the driving signal have an input audio band which has an upper bound at a maximum frequency. The spring structure is situated between the coupling plate and the actuator. The membrane has a first resonance frequency higher than the maximum frequency.

Abstract: A driving circuit is disclosed. The driving circuit includes a first node, coupled to at least a first air pulse generating element, wherein the driving circuit produces a first driving signal to the at least a first air pulse generating element via the first node; a second node, coupled to at least a second air pulse generating element, wherein the driving circuit produces a second driving signal to the at least a second air pulse generating element via the second node; a first swapping module, coupled to the first node and the second node, configured to be conducted within a first conduction interval; wherein a first voltage level at the first node and a second voltage level at the second node are substantially swapped after the first conduction interval.

Abstract: A sound producing device is disclosed. The sound producing device includes a first air pulse generating element, driven by a first driving signal comprising a first electrical pulse, the first electrical pulse comprises a first transition edge with a first transition polarity; and a second air pulse generating element, disposed adjacent to the first air pulse generating element, driven by a second driving signal comprising a second electrical pulse, the second electrical pulse comprises a second transition edge with a second transition polarity; wherein the first transition polarity is opposite to the second transition polarity; wherein the first transition edge generally coincides with the second transition edge; wherein air pulses generated by the first or the second air pulse generating element produce non-zero offset in terms of sound pressure level.

Abstract: An air pulse generating element is disclosed. The air pulse generating element includes a membrane, actuated according to a driving signal; a plate, wherein a chamber is formed between the plate and the membrane; wherein during a first phase of the driving signal, the membrane is actuated to change a volume within the chamber to generate an air pulse; wherein during a second phase of the driving signal, the membrane is actuated such that a gap is temporarily formed; wherein the temporarily formed gap is configured to provide a temporary air shunt to accelerate an air balancing process between a first air pressure at a first side of the membrane and a second air pressure at a second side of the membrane.

Abstract: The present invention provides a sound producing device comprising: an air pulse generating element and a control unit. The air pulse generating element comprises an air chamber and an actuator. The control unit, configured to generate a driving voltage applied to the actuator of the air pulse generating element, such that the air pulse generating element generates a plurality of air pulses in response to the driving voltage. The plurality of air pulses are at a pulse rate, and the pulse rate of the plurality of air pulses is higher than a maximum audible frequency.

Abstract: An audio apparatus includes a sound sensing device, a first amplifier and a sound producing device. The sound sensing device configured to detect an ambient sound pressure. The first amplifier coupled to the sound sensing device is configured to convert a first signal corresponding to the ambient sound pressure into a second signal with inverted polarity of the first signal. The sound producing device is coupled to the first amplifier and configured to produce a counter sound pressure corresponding to the second signal. Overall phase delay from the ambient sound pressure to the counter sound pressure is less than 25 degrees.

Abstract: A sound producing device is provided. The sound producing device includes a membrane, disposed within a chamber, controlled by a membrane control signal to cause a membrane movement; and a first deflector, disposed within a first opening by the membrane, controlled by a first deflector control signal to cause a first deflector rotation; wherein the sound producing device produces a plurality of air pulses via the membrane movement and the first deflector rotation, the plurality of air pulses has an air pulse rate, the air pulse rate is higher than a maximum human audible frequency; wherein the plurality of air pulses produces a non-zero offset in terms of sound pressure level, and the non-zero offset is a deviation from a zero sound pressure level.

Abstract: A sound producing device (SPD) is provided. The SPD comprises a membrane, having a resonance frequency and a resonance bandwidth; and an actuator, disposed on the membrane, receiving a driving signal corresponding to an input audio signal; wherein the input audio signal has an input audio band which is upper bounded by a maximum frequency; wherein the resonance frequency is higher than the maximum frequency plus a half of the resonance bandwidth.