Abstract: A noise filter circuit includes a filter and a transistor off-resistance control circuit. The filter includes a first transistor and a charge storage component. The first transistor has off-resistance when turned off or operated under sub-threshold region. A control terminal of the first transistor is not directly tied to a reference voltage, and is used to receive a first control voltage. The charge storage component has one terminal coupled to a connection terminal of the first transistor. The transistor off-resistance control circuit is coupled to the first transistor, and arranged to set the first control voltage for controlling the off-resistance of the first transistor.

Abstract: The present invention provides a power amplifier system configured to receive an input audio signal to generate an output audio signal is disclosed. The power amplifier system includes a reference signal generator, a dynamic headroom generator and a DC-DC converter. The reference signal generator is configured to generate a reference signal according to the input signal. The dynamic headroom generator is configured to generate an output reference signal according to the reference signal and a change rate of a signal, wherein the signal is the reference signal, the input audio signal, or correlated with the reference signal or the input audio signal. The DC-DC converter is configured to generate a supply voltage to a power amplifier, wherein a voltage level of the supply voltage is determined according to the output reference signal, and the power amplifier is configured to generate the output audio signal according to the input audio signal.

Abstract: The present invention provides a multi-stage amplifier including at least one inter-stage amplifier, an output amplifier, a high-pass filter and a feedback amplifier is disclosed. The at least one inter-stage amplifier is configured to amplify an input signal to generate a signal. The output amplifier is configured to receive the signal to generate an output signal. The high-pass filter is configured to filter the signal and the output signal to generate a filtered signal and a filtered output signal, respectively. The feedback amplifier is configured to receive the filtered signal and the filtered output signal to generate a feedback signal to an input terminal of one of the at least one inter-stage amplifier and the output amplifier.

Abstract: A DAC cell circuit includes: at least a DAC cell, including: a first MOSFET having a drain coupled to a first switch for receiving a first current and coupled to a second switch for generating a second current, a source coupled to ground, and a gate coupled to a first bias voltage; a capacitor coupled between the gate and the drain of the first MOSFET; and a dead-band switch coupled between the gate of the first MOSFET and the bias node. The dead-band switch is controlled by a signal which is periodic with respect to a frequency equal to an input data rate of the DAC cell, and the dead-band switch is open during a data transition.

Abstract: The present invention provides an amplifier circuit, wherein the amplifier circuit includes an input terminal, a capacitor, an amplifier, a feedback circuit and an aliasing tone cancellation circuit. The input terminal is configured to receive a first input signal. The capacitor is coupled to the input terminal. The amplifier is configured to receive the input signal through the capacitor to generate an output signal. The feedback circuit is coupled between an input node and an output node of the amplifier, and is configured to generate a feedback signal according to the output signal, wherein the feedback circuit includes a storage block including a switched-capacitor. The aliasing tone cancellation circuit is coupled between the input terminal of the amplifier circuit and the input node of the amplifier, and configured to generate a signal to cancel or reduce an aliasing tone of the feedback signal according to the input signal.

Abstract: The present invention provides a multi-stage amplifier, wherein the multi-stage amplifier includes a plurality of amplifier stages and a compensation circuit. The compensation circuit is coupled to an output terminal of one of the plurality of amplifier stages, and the compensation circuit includes a first auxiliary amplifier, a capacitor, a second auxiliary amplifier, a first resistor and a second resistor. The capacitor is coupled between an input terminal and an output terminal of the first auxiliary amplifier. The second auxiliary amplifier is coupled to the first auxiliary amplifier. The first resistor is coupled between an input terminal and an output terminal of the second auxiliary amplifier. The second resistor is coupled between an output terminal of the first auxiliary amplifier and a ground voltage.

Abstract: A digital-to-analog converter (DAC) includes a plurality of DAC cells, a mismatch error sorting circuit, and a dynamic element matching (DEM) circuit. The mismatch error sorting circuit generates a sorting result of the plurality of DAC cells according to mismatch error levels of the plurality of DAC cells. The DEM circuit shapes the mismatch error levels of the plurality of DAC cells according to the sorting result of the plurality of DAC cells.

Abstract: A tri-level digital-to-analog converter (DAC) element includes a first DAC cell. The first DAC cell includes a first reference circuit, a second reference circuit, and a switch circuit. The first reference circuit provides a first reference signal. The second reference circuit provides a second reference signal. The first switch circuit receives a control input from an input port of the tri-level DAC element, and controls interconnection between the first reference circuit, the second reference circuit, and an output port of the tri-level DAC element according to the control input. During a period in which the tri-level DAC element operates in a “0” state, the first switch circuit is arranged to couple at least one of the first reference circuit and the second reference circuit to the output port of the tri-level DAC element.

Abstract: An amplifier circuit includes a voltage-to-current conversion circuit and a current-to-voltage conversion circuit. The voltage-to-current conversion circuit generates a current signal according to an input voltage signal, and includes an operational transconductance amplifier (OTA) used to output the current signal at an output port of the OTA. The current-to-voltage conversion circuit generates an output voltage signal according to the current signal, and includes a linear amplifier (LA), wherein an input port of the LA is coupled to the output port of the OTA, and the output voltage signal is derived from an output signal at an output port of the LA.

Abstract: A noise filter circuit includes a filter and a transistor off-resistance control circuit. The filter includes a first transistor and a charge storage component. The first transistor has off-resistance when turned off or operated under sub-threshold region. A control terminal of the first transistor is not directly tied to a reference voltage, and is used to receive a first control voltage. The charge storage component has one terminal coupled to a connection terminal of the first transistor. The transistor off-resistance control circuit is coupled to the first transistor, and arranged to set the first control voltage for controlling the off-resistance of the first transistor.

Abstract: The present invention provides an amplifier system including an audio amplifier and a power converter. The audio amplifier is supplied by at least a first supply voltage and a second supply voltage, and the audio amplifier is configured to receive an audio signal to generate an output signal. The power converter includes only one inductor, and is configured to generate the first supply voltage and the second supply voltage according to an input voltage.

Abstract: A high-linearity amplifier including a main operational amplifier, a feedback circuit, and a compensation circuit is shown. The feedback circuit couples an output signal of the main operational amplifier to an input port of the main operational amplifier. The compensation circuit couples a former-stage circuit of the amplifier to the input port of the main operational amplifier to compensate for the non-linearity of the feedback circuit. The compensation circuit and the feedback circuit form an inverse paralleling linearization architecture. In the inverse paralleling linearization architecture, a resistor in the feedback circuit corresponds to a resistor in the compensation circuit which is biased in an inversed way in comparison with the corresponding resistor in the feedback circuit.

Abstract: The present invention provides an amplifier including an input stage, an amplifier stage, a power stage and a de-gain stage. The input stage is configured to receive an input signal to generate an amplified signal. The amplifier stage is configured to generate a first driving signal and a second driving signal according to the amplified signal. The power stage comprises a first input terminal and a second input terminal, wherein the power stage is coupled to a supply voltage and a ground voltage, for receiving the first driving signal and the second driving signal from the first input terminal and the second input terminal, respectively, and generating an output signal.

Abstract: The present invention provides a linear amplifier including an amplifier stage, a DC-shifting stage, a compensation network and a power stage. The amplifier stage is configured to generate a first signal and a second signal. The DC-shifting stage is configured to adjust a DC voltage of the first signal and a DC voltage of the second signal to generate an adjusted first signal and an adjusted second signal. The compensation network is configured to generate a first driving signal and a second driving signal according to the first signal, the second signal, the adjusted first signal and the adjusted second signal. The power stage is configured to generate an output signal according to the first driving signal and the second driving signal.

Abstract: The present invention provides an amplifier circuit, wherein the amplifier circuit includes an input terminal, a capacitor, an amplifier, a feedback circuit and an aliasing tone cancellation circuit. The input terminal is configured to receive a first input signal. The capacitor is coupled to the input terminal. The amplifier is configured to receive the input signal through the capacitor to generate an output signal. The feedback circuit is coupled between an input node and an output node of the amplifier, and is configured to generate a feedback signal according to the output signal, wherein the feedback circuit includes a storage block including a switched-capacitor. The aliasing tone cancellation circuit is coupled between the input terminal of the amplifier circuit and the input node of the amplifier, and configured to generate a signal to cancel or reduce an aliasing tone of the feedback signal according to the input signal.

Abstract: A high-linearity amplifier including a main operational amplifier, a feedback circuit, and a compensation circuit is shown. The feedback circuit couples an output signal of the main operational amplifier to an input port of the main operational amplifier. The compensation circuit couples a former-stage circuit of the amplifier to the input port of the main operational amplifier to compensate for the non-linearity of the feedback circuit. The compensation circuit and the feedback circuit form an inverse paralleling linearization architecture. In the inverse paralleling linearization architecture, a resistor in the feedback circuit corresponds to a resistor in the compensation circuit which is biased in an inversed way in comparison with the corresponding resistor in the feedback circuit.

Abstract: A high-linearity amplifier including a main operational amplifier, a feedback circuit, and a compensation circuit is shown. The feedback circuit couples an output signal of the main operational amplifier to an input port of the main operational amplifier. The compensation circuit is coupled to the input port of the main operational amplifier to compensate for the non-linearity of the feedback circuit. A signal coupled to the input port of the main operational amplifier through the compensation circuit has an inverse phase compared to the output signal of the main operational amplifier.

Abstract: A multi-stage amplifier with a high signal-to-noise ratio is introduced. Multiple amplification stages are cascaded between an input terminal and an output terminal of the amplifier. A controller switches the output stage among the multiple amplification stages from a normal mode to an attenuation mode in response to the amplifier input being lower than the threshold. In the attenuation mode, the output stage provides an attenuation resistor coupled in series with the load resistor of the amplifier. Noise is successfully attenuated by the attenuation-mode output stage.

Abstract: An amplifier circuit includes a voltage-to-current conversion circuit and a current-to-voltage conversion circuit. The voltage-to-current conversion circuit generates a current signal according to an input voltage signal, and includes an operational transconductance amplifier (OTA) used to output the current signal at an output port of the OTA. The current-to-voltage conversion circuit generates an output voltage signal according to the current signal, and includes a linear amplifier (LA), wherein an input port of the LA is coupled to the output port of the OTA, and the output voltage signal is derived from an output signal at an output port of the LA.

Abstract: The present invention provides an amplifier including a DAC, an analog signal processing circuit, a digital signal processing circuit, a signal detector and a driving stage is disclosed. The DAC is configured to perform a digital-to-analog conversion operation on a digital input signal to generate an analog input signal. The analog signal processing circuit is configured to generate a first processed signal according to the analog input signal and a feedback signal. The digital signal processing circuit is configured to process the digital input signal to generate a second processed signal. The signal detector is configured to detect strength of the digital input signal to generate a mode selection signal. The driving stage is configured to refer to the mode selection signal to receive one of the first processed signal and the second processed signal to generate an output signal, wherein the feedback signal is generated by the output signal.