Pulse shaping FM demodular with low noise where capacitor charge starts on input signal edge

An FM demodulator comprising a pulse shaper, characterized in that said pulse shaper is implemented as an integrated circuit in a semiconductor material and comprises:

• a series arrangement of at least a load and a capacitance, said load being coupled to a first supply terminal;
• a switching device for charging the capacitance in a first state, initiated by a first edge of the frequency-modulated input signal, and for discharging the capacitance in a second state, initiated by a second edge following the first edge;
• a first transistor having a base-emitter junction arranged across the capacitance, and having a collector coupled to the first supply terminal or to a second supply terminal for limiting a voltage across said capacitance;
• and
• output means for supplying an output signal to an output terminal intended to have a low-pass filter coupled thereto, said output signal varying with a current through the capacitance, a charging time and a discharging time of the capacitance being smaller than a minimum time between two successive edges of the frequency-modulated input signal.

A receiver comprising, arranged in this order, an input section, an FM demodulator, to which a frequency-modulated input signal is applied, and an LF section, said FM demodulator comprising a pulse shaper and a low-pass filter, characterized in that

• the pulse shaper comprises:
• a series arrangement of at least a load and a capacitance, said load being coupled to a first supply terminal;
• a switching device which charges said capacitance in a first state, initiated by a first edge of the frequency-modulated input signal, and which discharges said capacitance in a second state, initiated by a second edge following the first edge;
• a first transistor having a base-emitter junction arranged across said capacitance, and having a collector coupled to a second supply terminal for limiting a voltage across said capacitance;
• and
• output means for generating an output signal which varies with a current through said capacitance, wherein a charging time and a discharging time of said capacitance are smaller than a minimum time between two successive edges of the frequency-modulated input signal.