Example circuitry includes a first circuit to provide a low signal; a second circuit to provide a high signal, where the high signal has a greater voltage magnitude than the low signal; and a differential amplifier configured to receive the low signal from the first circuit and the high signal from the second circuit. The differential amplifier is for producing an output voltage that is based on the high signal and the low signal. The example circuitry includes a first measurement circuit to measure the output voltage; a second measurement circuit to measure the low signal at the first circuit; and processing logic to determine a differential measurement based on the output voltage measured by the first measurement circuit, the low signal measured by the second measurement circuit, and calibration values obtained for the circuitry.

A method and a system of calibrating a DC offset voltage on a resistor load are provided. The system may include a first operational amplifier, a second operational amplifier, a comparator, a digital signal processor, and a digital to analog convertor. At a calibration mode, under control of the digital signal processor, the system may utilize open-loop high gain characteristics of the first operational amplifier and the comparator to automatically detect and calibrate the DC offset voltage. At an operation mode, the system may automatically compensate the DC offset voltage based on the calibration of the DC offset voltage. In this way, the system and the method can automatically detect, calibrate, and compensate the DC offset voltage with reduced cost and technical complexity.

A receiver includes a first T-coil circuit at an input of the receiver and configured to receive an input signal, a termination impedance coupled to the first T-coil circuit and configured to match an impedance of a transmission line coupled to the first T-coil circuit, and an amplifier including a first input and a second input and configured to amplify a differential signal at the first and second inputs, a calibration switch coupled to the amplifier and configured to selectively electrically connect or disconnect the first and second inputs of the amplifier, and a first receive switch configured to selectively electrically connect or disconnect a center node of the first T-coil circuit and the amplifier.

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.

An example process includes reducing a quality factor of a first tunable bandpass filter, used, for example, in a low-noise amplifier stage of a polar receiver. A first wideband test signal centered at a desired center frequency of a second tunable bandpass filter is received. A frequency response of the second tunable bandpass filter to the first wideband test signal is estimated using a Fast Fourier Transform (FFT) signal processor. At least a resonant frequency or a quality factor of the second tunable bandpass filter are calibrated based at least in part on a portion of the estimated frequency response of the second tunable bandpass filter obtained from the FFT signal processor. Frequency response characteristics of the first tunable bandpass filter may be similarly tuned in accordance with the example process.

Example circuitry includes a first circuit to provide a low signal; a second circuit to provide a high signal, where the high signal has a greater voltage magnitude than the low signal; and a differential amplifier configured to receive the low signal from the first circuit and the high signal from the second circuit. The differential amplifier is for producing an output voltage that is based on the high signal and the low signal. The example circuitry includes a first measurement circuit to measure the output voltage; a second measurement circuit to measure the low signal at the first circuit; and processing logic to determine a differential measurement based on the output voltage measured by the first measurement circuit, the low signal measured by the second measurement circuit, and calibration values obtained for the circuitry.

An apparatus for calibrating a differential circuit that includes a differential integrator having an input, a gain, and an output connected to a comparator. The differential integrator output is chargeable to a threshold prior to an integration period. The differential integrator integrates the input during the integration period such that the differential integrator output goes toward zero from the threshold. The comparator detects the output of the differential integrator reaching zero. The apparatus includes a closed-loop gain trim circuit to perform a coarse calibration to adjust and set the gain of the differential integrator and a reference generator that generates the threshold to which the differential integrator output is pre-charged. The reference generator is trimmable during a fine calibration to adjust and set the threshold to correct for residual gain error in the differential circuit remaining after the coarse calibration is performed.

Disclosed herein is a circuit including a differential amplifier having a pair of input transistors coupled in a differential arrangement between adjustable current sources and receiving input differential signals from a pair of input voltage regulators. The adjustable current sources are configured to source more current to the pair of input transistors than current that is sunk from the pair of input transistors. A first amplifier has inputs coupled to receive differential output voltages from the differential amplifier. A second amplifier has inputs coupled to receive amplified differential output voltages from the first amplifier. A low pass filter has inputs coupled to receive further amplified differential output voltages from the second amplifier and produce final differential output voltages.

A method and a system of calibrating a DC offset voltage on a resistor load are provided. The system may include a first operational amplifier, a second operational amplifier, a comparator, a digital signal processor, and a digital to analog convertor. At a calibration mode, under control of the digital signal processor, the system may utilize open-loop high gain characteristics of the first operational amplifier and the comparator to automatically detect and calibrate the DC offset voltage. At an operation mode, the system may automatically compensate the DC offset voltage based on the calibration of the DC offset voltage. In this way, the system and the method can automatically detect, calibrate, and compensate the DC offset voltage with reduced cost and technical complexity.

A regulator includes an operational amplifier, a programmable offset voltage, and a circuit. The operational amplifier includes a non-inverting input, an inverting input, and an output. The programmable offset voltage is configured to cancel a built-in offset voltage of the regulator based on a code. The circuit is configured to set the code based on a sensed built-in offset voltage of the regulator in response to an offset cancellation calibration mode enable signal.