A calibration apparatus is used for calibrating characteristics of a power amplifier (PA) in a transmitter. The calibration apparatus includes an adaptive bias generator circuit that is used to track an envelope of an input signal received by control terminals of transistors of the PA and generate an adaptive bias voltage to the control terminals of the input transistors in response to the envelope of the input signal.

To provide a variable reference voltage source for which a measuring instrument is unnecessary for calibration on the outside. A variable reference voltage source that generates a variable reference voltage corresponding to setting data set from outside includes a control unit including a calibration control unit that controls operation for calibrating an offset and a predetermined unit voltage inside the variable reference voltage source and an output control unit that controls operation for outputting the variable reference voltage, a reference voltage unit that outputs a reference voltage Vref, and an integrated-voltage generating unit that repeats, when the calibration control unit controls the operation, an integrating operation until an integrated voltage obtained by integrating the predetermined unit voltage becomes equal to the reference voltage Vref and outputs, when the output control unit controls the operation, the variable reference voltage corresponding to the setting data.

An internal voltage offset between a positive input and a negative input of a first operational amplifier is compensated. The negative input and the positive input of the first operational amplifier are coupled at the same voltage level. A comparison current generated at an output of the first operational amplifier has a sign that is representative of a sign of the internal voltage offset. The output of the first operational amplifier is biased to a threshold voltage using a current-to-voltage converter. A control voltage is generated from a sum of the threshold voltage and a voltage conversion of the comparison current. Compensation for the internal voltage offset between the positive and negative inputs of the first operational amplifier is made dependent on the control voltage.

A method for calibrating the DC operating point of a PWM receiver circuit is disclosed. The PWM receiving circuit includes an envelop detector having a first resistor string, and includes a bias circuit having a second resistor string and a plurality of switches. The second resistor string is coupled between a supply voltage and a reference voltage and functions as a voltage divider. Each switch, when closed, accesses a second voltage at a node of the second resistor string connected to the closed switch. To perform the calibration process, the plurality of switches is closed one at a time, and the second voltage is compared with a first voltage at a first node of the first resistor string. The switch that, when closed, produces the smallest difference between the first voltage and the second voltage remains closed after the calibration process, and is used for demodulating the PWM signal.

Disclosed herein is a method including sinking current from a pair of input transistors of a differential amplifier while sourcing more current to the pair of input transistors than is sunk. The method further includes generating a pair of input differential signals using a pair of input voltage regulators, and amplifying a difference between the pair of input differential signals to produce a pair of differential output voltages, using the differential amplifier. The method also includes amplifying the pair of differential output voltages using at least one voltage gain amplifier, and generating control signals for current sources that source the current to the pair of input transistors of the differential amplifier, from the pair of differential output voltages after at least amplification.

A circuit arrangement is provided which includes an array of stages for photon counting current to voltage conversion. Each stage includes a tunable operational transconductance amplifier and a feedback network forming a feedback loop of the operational transconductance amplifier. Each stage is configured to provide an output signal as a function of an input signal that is provided to the amplifier input of the operational transconductance amplifier, wherein the input signal comprises one or more current pulses and the output signal comprises one or more voltage pulses. With the tunable operational transconductance amplifier the transconductance of a stage can be tuned so that differences in peaking time and gain are avoided. Furthermore, an imaging device and a method for operating a circuit arrangement are provided.

A shaper circuit includes a first amplifier including an input and an output, the input being configured to receive an input signal, which includes one or more current pulses, a feedback component coupled to the output and to the input of the first amplifier thereby forming a feedback loop of the first amplifier, and an RC component coupled to the output of the first amplifier and to a reference potential terminal. Therein the shaper circuit is configured to provide an output signal as a function of the input signal, the output signal including one or more voltage pulses, and the RC component is configured to largely cancel a low frequency pole of the feedback loop of the first amplifier.

A method for calibrating the DC operating point of a PWM receiver circuit is disclosed. The PWM receiving circuit includes an envelope detector having a first resistor string, and includes a bias circuit having a second resistor string and a plurality of switches. The second resistor string is coupled between a supply voltage and a reference voltage and functions as a voltage divider. Each switch, when closed, accesses a second voltage at a node of the second resistor string connected to the closed switch. To perform the calibration process, the plurality of switches is closed one at a time, and the second voltage is compared with a first voltage at a first node of the first resistor string. The switch that, when closed, produces the smallest difference between the first voltage and the second voltage remains closed after the calibration process, and is used for demodulating the PWM signal.

The present disclosure relates to a device comprising two error amplifier stages having their first inputs interconnected, their second inputs interconnected and their outputs coupled to an output of the device, each stage comprising an operational amplifier; a circuit for calibrating the amplifier; a switch coupling an input of the amplifier to the first input; a switch coupling another input of the amplifier to the second input; a switch coupling an output of the amplifier to the stage output; a switch having on state which short-circuits the inputs of the amplifier; and a switch coupling the output of the amplifier to the calibration circuit.

An offset compensated differential amplifier employing a multi-tan h circuit comprising differential pairs coupled in parallel to compensate for an offset voltage of the output voltage in the offset compensation calibration mode is disclosed. The differential pairs each include a compensation transistor coupled to the positive internal node and a reference transistor coupled to the negative internal node. Each compensation transistor receives the compensation control voltage and each reference transistor receives a different reference voltage. The multi-tan h circuit generates an offset compensation voltage on the positive and negative internal nodes based on a difference between the compensation control voltage and the different reference voltages. The multi-tan h circuit comprises a larger linear range than a hyperbolic tangent current transfer function of a single differential pair. The offset compensated differential amplifier provides offset compensation with improved linearity and a finer granularity compared to a conventional differential amplifier.