Abstract: A circuit for biasing a transducer including a first plate and a second plate includes a front-end buffer and a charge pump. The front-end buffer generates an internal signal at an internal node in response to a voltage signal of the second plate. The transducer receives the incident sound wave at the first plate to generate the voltage signal at the second plate. The charge pump boosts the internal signal into a boost voltage at the first plate according to a first clock signal.

Abstract: A digital microphone is provided. The digital microphone includes an acoustic sensor, a bias generator, first and second attenuators, a buffer, an amplifier, an ADC, and a controller. The acoustic sensor transfers an acoustic signal to a voltage signal. The bias generator provides a bias voltage to the acoustic sensor. The first attenuator attenuates the voltage signal by a first attenuation value. The buffer buffers the voltage signal to generate a buffered voltage signal. The amplifier amplifies the buffered voltage signal to generate an amplified signal. The ADC converts the amplified signal to a data signal with a digital format. The second attenuator attenuates the data signal by a second attenuation value. The controller determines whether the amplified signal is larger than a reference value and adjusts the bias voltage and the first and second attenuation values of the first and second attenuators according to the result determined by the controller.

Abstract: A charge pump includes a first unidirectional conducting device, a flying capacitor, a second unidirectional conducting device, an output capacitor, a first switch, and a second switch. The first unidirectional conducting device unidirectionally couples a supply voltage to an internal node. The flying capacitor is coupled between the internal node and a clock signal. The second unidirectional conducting device unidirectionally couples the internal node to an output node. The output capacitor is coupled between the output node and a ground. The first switch couples a discharge node to the ground according to a discharge signal. The second switch couples the output node to the discharge node according to the voltage of the internal node.

Abstract: A circuit for biasing a transducer including a first plate and a second plate includes a front-end buffer and a charge pump. The front-end buffer generates an internal signal at an internal node in response to a voltage signal of the second plate. The transducer receives the incident sound wave at the first plate to generate the voltage signal at the second plate. The charge pump boosts the internal signal into a boost voltage at the first plate according to a first clock signal.

Abstract: A charge pump includes a first unidirectional conducting device, a flying capacitor, a second unidirectional conducting device, an output capacitor, a first switch, and a second switch. The first unidirectional conducting device unidirectionally couples a supply voltage to an internal node. The flying capacitor is coupled between the internal node and a clock signal. The second unidirectional conducting device unidirectionally couples the internal node to an output node. The output capacitor is coupled between the output node and a ground. The first switch couples a discharge node to the ground according to a discharge signal. The second switch couples the output node to the discharge node according to the voltage of the internal node.

Abstract: A digital microphone is provided. The digital microphone includes an acoustic sensor, a bias generator, first and second attenuators, a buffer, an amplifier, an ADC, and a controller. The acoustic sensor transfers an acoustic signal to a voltage signal. The bias generator provides a bias voltage to the acoustic sensor. The first attenuator attenuates the voltage signal by a first attenuation value. The buffer buffers the voltage signal to generate a buffered voltage signal. The amplifier amplifies the buffered voltage signal to generate an amplified signal. The ADC converts the amplified signal to a data signal with a digital format. The second attenuator attenuates the data signal by a second attenuation value. The controller determines whether the amplified signal is larger than a reference value and adjusts the bias voltage and the first and second attenuation values of the first and second attenuators according to the result determined by the controller.

Abstract: An operational amplifier circuit with improved feedback factor is provided that includes an input impedance, an operational amplifier, and a current conveyor. The input impedance is operable to receive an input signal. The operational amplifier comprises an inverting input node, a non-inverting input node, and an output node. The operational amplifier is operable to generate an output signal at the output node based on the input signal. The current conveyor is coupled between the input impedance and the inverting input node of the operational amplifier. The current conveyor is operable to provide a low impedance to the input impedance and a high impedance to the operational amplifier.