摘要:
A sample and hold demodulator circuit for use in an automotive immobiliser to recover modulation information from a received modulated carrier signal (V RD ), the circuit comprising: sample and hold means for sampling the received signal to recover the modulation information therein, and control means (214) coupled to the sample and hold means for controlling operation thereof, the control means comprising shift register means (252) for receiving the received signal (V RD ) and for producing at its outputs signals (SAMPLE, SAMPLE2, LATCH) for controlling operation of the sample and hold means. The circuit provides a single IC solution, allowing amplitude and phase demodulation to be performed with a single sample and hold circuit without requiring a dedicated microcontroller or extra interfaces or wires to a main electronic control unit elsewhere in the automobile.