Amplitude shift keying demodulator and method for demodulating an ask signal

An ASK demodulator, comprising:

• a rectification circuit configured to receive and rectify an ASK signal to generate a rectified current;
• an active load circuit coupled to the rectification circuit and configured to receive the rectified current and present an impedance which is inversely proportional to at least a part of the rectified current when a frequency of a base band signal meets a preset condition;
• and
• a comparator coupled to the rectification circuit and the active load circuit and configured to receive a reference voltage and a voltage generated based on, at least in part, the rectified current and the impedance, and compare the reference voltage and the generated voltage to generate a demodulated signal;
• wherein the active load circuit comprises:
• a first MOSFET with a source coupled to a power supply and a drain coupled to the rectification circuit;
• a capacitor with a first end coupled to the power supply and a second end coupled to a gate of the first MOSFET;
• a second MOSFET with a source coupled to the gate of the first MOSFET and the second end of the capacitor, a gate coupled to the drain of the first MOSFET and a drain which is grounded.