Abstract: Automatic ambient light cancellation for an optical front end. The present disclosure includes a coarse loop and fine loop in a feedback circuit configured to cancel out currents generated by detection of ambient light. An optical front end comprises a single-ended photo-diode connected to a transimpedance amplifier (TIA) followed by a buffer stage to generate differential output. A feedback loop controls a current digital to analog converter (iDAC) which is used to cancel out undesired current (e.g., from ambient light). This results in the TIA from saturating and maintain good signal quality with greater sensitivity.

Abstract: Automatic ambient light cancellation for an optical front end. The present disclosure includes a coarse loop and fine loop in a feedback circuit configured to cancel out currents generated by detection of ambient light. An optical front end comprises a single-ended photo-diode connected to a transimpedance amplifier (TIA) followed by a buffer stage to generate differential output. A feedback loop controls a current digital to analog converter (iDAC) which is used to cancel out undesired current (e.g., from ambient light). This results in the TIA from saturating and maintain good signal quality with greater sensitivity.

Abstract: Disclosed herein are transconductance circuits, as well as related methods and devices. In some embodiments, a transconductance circuit may include an amplifier having a first input coupled to a voltage input of the transconductance circuit, and a switch coupled between an output of the amplifier and a second input of the amplifier.

Abstract: Low-frequency Noise Cancellation Method for Optical Measurement Systems. The present disclosure provides a low frequency noise cancellation method for optical measurement system, An optical measurement system has a transmitter to drive an LED and a receiver connected to a photodiode. The LED driver will generate a pulse signal to drive the LED and act as the radiation source for the optical measurement. Consequently, the receiver will convert the received photo-diode current to a voltage signal. The signal will then be digitized by an ADC for further processing. A current DAC circuit IDAC is added at the front of the receiver and has the same timing control with the LED driver to cancel the DC portion of the received current.

Abstract: Disclosed herein are transconductance circuits, as well as related methods and devices. In some embodiments, a transconductance circuit may include an amplifier having a first input coupled to a voltage input of the transconductance circuit, and a switch coupled between an output of the amplifier and a second input of the amplifier.

Abstract: Disclosed herein are transconductance circuits, as well as related methods and devices. In some embodiments, a transconductance circuit may include an amplifier having a first input coupled to a voltage input of the transconductance circuit, and a switch coupled between an output of the amplifier and a second input of the amplifier.

Abstract: Disclosed herein are transimpedance circuits, as well as related methods and devices. In some embodiments, a transimpedance circuit may include a current source bias terminal, a current source output terminal, and a transimpedance amplifier coupled to the current source output terminal, wherein voltage signals at the current source bias terminal are correlated with voltage signals at the current source output terminal. In some embodiments, the current source may be a photodiode.

Abstract: Disclosed herein are transimpedance circuits, as well as related methods and devices. In some embodiments, a transimpedance circuit may include a current source bias terminal, a current source output terminal, and a transimpedance amplifier coupled to the current source output terminal, wherein voltage signals at the current source bias terminal are correlated with voltage signals at the current source output terminal. In some embodiments, the current source may be a photodiode.

Abstract: Disclosed herein are transconductance circuits, as well as related methods and devices. In some embodiments, a transconductance circuit may include an amplifier having a first input coupled to a voltage input of the transconductance circuit, and a switch coupled between an output of the amplifier and a second input of the amplifier.

Abstract: This disclosure describes techniques for compensating for amplifier drift. An amplifier is configured to generate an output that triggers a charge counter to generate a charge count value based on a charge count signal. A current digital-to-analog converter (IDAC) is coupled to the amplifier and configured to provide an offset current to a first input of the amplifier. An offset correction circuit is configured to: determine whether a duty cycle associated with the amplifier exceeds a specified threshold and generate a signal to cause the MAC to adjust the value of the offset current to compensate for amplifier drift based on determining whether the duty cycle exceeds the specified threshold.

Abstract: This disclosure describes techniques for compensating for amplifier drift. An amplifier is configured to generate an output that triggers a charge counter to generate a charge count value based on a charge count signal. A current digital-to-analog converter (IDAC) is coupled to the amplifier and configured to provide an offset current to a first input of the amplifier. An offset correction circuit is configured to: determine whether a duty cycle associated with the amplifier exceeds a specified threshold and generate a signal to cause the MAC to adjust the value of the offset current to compensate for amplifier drift based on determining whether the duty cycle exceeds the specified threshold.

Abstract: In certain applications, differential amplifiers with infinite common mode rejection ratios are desirable. However, resistance mismatches due to imperfections in the manufacturing create finite common mode rejection ratio in differential amplifiers degrading their performance. Disclosed are apparatus and method for improving the common mode rejection ratio of practical differential amplifiers.

Abstract: In certain applications, differential amplifiers with infinite common mode rejection ratios are desirable. However, resistance mismatches due to imperfections in the manufacturing create finite common mode rejection ratio in differential amplifiers degrading their performance. Disclosed are apparatus and method for improving the common mode rejection ratio of practical differential amplifiers.

Abstract: An amplifier system may include a power stage having inputs for three different supply voltages and an output for coupling to a load, a controller to generate control signals to the power stage that cause the power stage to vary an output voltage applied to the load among more than three distinct voltage levels, a monitor to provide a first control signal to the controller based on an input voltage signal, and a feedback system to provide a second control signal to the controller based on comparison of the output voltage and the input signal.

Abstract: A circuit may include a detector, a modulator, a switch, and a stabilizer. The detector may detect current supplied to an output of the circuit to generate an overcurrent signal. The modulator may modulate a pulse signal based upon the output of the circuit. The switch may control a power stage to generate the output of the circuit based upon the overcurrent signal and the pulse signal. The stabilizer may send an offset signal to the modulator. The stabilizer may generate the offset signal with a magnitude adjusted based upon the overcurrent signal, and the modulator may adjust the pulse signal based upon the offset signal.

Abstract: An amplifier system may include a power stage having inputs for three different supply voltages and an output for coupling to a load, a controller to generate control signals to the power stage that cause the power stage to vary an output voltage applied to the load among more than three distinct voltage levels, a monitor to provide a first control signal to the controller based on an input voltage signal, and a feedback system to provide a second control signal to the controller based on comparison of the output voltage and the input signal.

Abstract: Techniques to generate boosted multi-level switched output voltages from a boosted multi-level Class D amplifier. The amplifier may include a multi-level H-bridge, which may include pairs of transistor switches coupled to a first, second, and third supply potential. The second supply potential may be a boosted representation of the first supply potential. The amplifier may receive an input signal, and from the input signal may generate pulse-modulated control signals to control the switching for the transistor switches of the multi-level H-bridge. The amplifier may generate the boosted multi-level switched output voltages from output nodes of the multi-level H-bridge.

Abstract: Techniques to generate boosted multi-level switched output voltages from a boosted multi-level Class D amplifier. The amplifier may include a multi-level H-bridge, which may include pairs of transistor switches coupled to a first, second, and third supply potential. The second supply potential may be a boosted representation of the first supply potential. The amplifier may receive an input signal, and from the input signal may generate pulse-modulated control signals to control the switching for the transistor switches of the multi-level H-bridge. The amplifier may generate the boosted multi-level switched output voltages from output nodes of the multi-level H-bridge.