Shaper circuit, photon counting circuit and x-ray apparatus

A shaper circuit comprising:

• a first amplifier comprising an input and an output, the input being configured to receive an input signal, which comprises 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,
• wherein the shaper circuit is configured to provide an output signal as a function of the input signal, the output signal comprising one or more voltage pulses,
• wherein the RC component is configured to largely cancel a low frequency pole of the feedback loop of the first amplifier,
• wherein the RC component comprises a resistor and a capacitor which are connected in series, the resistor or the capacitor being directly connected to the output of the first amplifier,
• wherein a resistance of the resistor of the RC component is smaller than or equal to a resistance of an internal output resistor of the first amplifier,
• wherein a capacitance of the capacitor of the RC component is larger than a load capacitance occurring at the output of the first amplifier,
• wherein the first amplifier comprises an operational transconductance amplifier and a transconductance of said first amplifier is adjusted in dependence on an input capacitance occurring at the input of the shaper circuit, and
• wherein the shaper circuit is configured for use in a photon counting circuit.