Demodulation circuit and demodulation method
AssigneeInfineon Technologies AG
InventorsWalter Kargl, Mario Kupnik, Ernst Neuhold
Life of this patent
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Abstract
Two capacitors are provided for demodulating an amplitude-modulated signal and can be supplied with a signal that is rectified by a diode and that is at a voltage. The half-cycles of this signal are used for alternately charging the first or second capacitor using a switch. The capacitors are discharged using switches. Comparing the amplitude values, which are stored in the capacitors, of successive half-cycles in an evaluation unit allows simple and precise demodulation, which can be achieved with few components and can be carried out at very high frequencies.
Claims7
An amplitude demodulation circuit, comprising:
- a signal input for obtaining an amplitude-modulated signal;
- a first capacitor for obtaining a signal derived from the amplitude-modulated signal, said first capacitor having a first connection connected to ground, said first capacitor for supplying a first voltage being tapped off across said first capacitor;
- a first discharging apparatus connected in parallel with said first capacitor;
- a second capacitor for obtaining a signal derived from the amplitude-modulated signal, said second capacitor having a first connection connected to ground, said second capacitor for supplying a second voltage being tapped off across said second capacitor;
- a second discharging apparatus connected in parallel with said second capacitor;
- a device for alternately storing rectified successive half-cycles of the amplitude-modulated signal on said first capacitor and said second capacitor, said device coupling said first capacitor and said second capacitor to said signal input;
- and
- an evaluation unit for comparing the first voltage and the second voltage and for supplying an amplitude-demodulated signal derived from the amplitude-modulated signal.
A method for demodulating an amplitude-modulated signal, which comprises:
- supplying the amplitude-modulated signal to a first diode;
- obtaining a rectified signal by rectifying the amplitude-modulated signal;
- charging a first capacitor to a first capacitor voltage with a first half-cycle of the rectified signal;
- charging a second capacitor to a second capacitor voltage with a second half-cycle of the rectified signal;
- comparing the first capacitor voltage and the second capacitor voltage and detecting any amplitude change;
- discharging the first capacitor;
- and
- discharging the second capacitor.
Dependencies are inferred from the claim text.