Demodulator using digital circuitry
AssigneeCelio Semiconductor Corporation
InventorAlan D. Devilbiss
Life of this patent
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Abstract
A demodulator converts a voltage input to an output voltage. The demodulator has a voltage-controlled oscillator (VCO), a counter, a holding apparatus, and a digital compare apparatus. The VCO generates a signal having a frequency proportional to the analog input voltage. The counter counts each cycle of the signal generated by the VCO and outputs a count signal representative of the cycle count. The holding apparatus holds the count signal and generates a held count signal. The digital compare apparatus compares the count signal and the held count signal and generates the digital output.
Claims12
A demodulator for converting an analog input voltage to an output voltage, the demodulator comprising:
- (a) a voltage-controlled oscillator (VCO) configured to generate a signal having a frequency proportional to the analog input voltage;
- (b) a counter configured to count each cycle of the signal generated by the VCO and output a count signal representative of the cycle count;
- (c) a holding apparatus configured to hold the count signal and generate a held count signal and
- (d) a digital compare apparatus configured to compare the count signal and the held count signal and generate the digital output.
A method for converting an analog input voltage to an output voltage, method comprising:
- (a) generating a voltage signal having a frequency proportional to the analog input voltage source;
- (b) counting the cycles of the voltage signal and generating a count signal representative of the cycle count;
- (c) holding the count signal;
- (d) resetting the cycle count;
- (e) counting the cycles of the voltage signal and generating a count signal representative of the cycle count;
- (f) comparing the count signal with the held count signal;
- and
- (g) generating the output voltage from the comparison of the count signal with the held count signal.
A demodulator for converting an analog input voltage to an output voltage, the demodulator supplied with a power supply voltage source and a reset clock, the demodulator comprising:
- (a) a voltage-controlled oscillator (VCO) having an input terminal and an output terminal, the analog input voltage applied to the input terminal, the VCO configured to generate a signal having a frequency at the output terminal proportional to the analog input voltage source applied to the input terminal;
- (b) a counter having an input terminal, an output terminal, and a reset terminal, the input terminal coupled to the output terminal of the VCO and the reset terminal connected to the reset clock;
- (c) a holding apparatus having an input terminal, an output terminal, and a reset terminal, the input terminal connected to the output terminal of the counter and the reset terminal coupled to the reset clock;
- and
- (d) a digital compare apparatus having first and second input terminals, an output terminal, and a reset terminal, the first input terminal connected to the output of the holding apparatus, the second input terminal connected to the output of the counter, and the reset terminal connected to the reset clock, the digital compare apparatus configured to provide the digital output at the output terminal.
Dependencies are inferred from the claim text.