Demodulator, Chip And Method For Digital Demodulating An Fsk Signal
First Claim
1. In a high data rate receiver for an FSK data transmission system having a data transfer protocol, a digital demodulator for demodulating an FSK signal having a data rate from a carrier signal having a pair of carrier frequencies, the digital demodulator generating a serial data bit stream based on the FSK carrier signal and generating a synchronized constant frequency clock signal from the carrier frequencies based on the data transfer protocol for sampling the serial data bit stream wherein both the data transfer protocol and the demodulator are fully digital to make the system robust.
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Abstract
A demodulator, chip and method for digitally demodulating an FSK signal utilizing a digital data transfer protocol and a digital demodulator circuit have been developed. The data-rate approaches the carrier-frequency. The one application for this technique is in the magnetically powered wireless systems such as biomedical implants and radio frequency identification (RFID) tags with high data rates above 1 Mbps. The demodulator circuit extracts the serial data bit-stream and a constant-frequency clock from an FSK carrier signal in the 1˜20 MHZ range, which can power the wireless system as well. The digital demodulator circuit is implemented entirely with digital circuitry and is called a digital-FSK (DFSK) demodulator.
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Citations
20 Claims
- 1. In a high data rate receiver for an FSK data transmission system having a data transfer protocol, a digital demodulator for demodulating an FSK signal having a data rate from a carrier signal having a pair of carrier frequencies, the digital demodulator generating a serial data bit stream based on the FSK carrier signal and generating a synchronized constant frequency clock signal from the carrier frequencies based on the data transfer protocol for sampling the serial data bit stream wherein both the data transfer protocol and the demodulator are fully digital to make the system robust.
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10. The demodulator as claimed in 9, wherein the receiver is a wireless biomedical implant.
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11. An FSK demodulator chip for an FSK data transmission system having a fully digital data transfer protocol, the chip comprising:
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a substrate; and a digital demodulator formed on the substrate for demodulating an FSK signal having a data rate from a carrier signal having a pair of carrier frequencies wherein the demodulator generates a serial data bit stream based on the FSK carrier signal and generates a synchronized constant frequency clock signal from the carrier frequencies based on the data transfer protocol for sampling the serial data bit stream and wherein the demodulator is fully digital to minimize the amount of surface area occupied by the demodulator on the substrate. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A method for demodulating an FSK signal having a data rate from a carrier signal having a pair of carrier frequencies in an FSK transmission system having a digital data transfer protocol, the method comprising:
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digitally measuring the period of each received positive half cycle of the FSK carrier signal to obtain a series of pulses which distinguish between long and short FSK carrier cycles; digitally generating a serial data bit stream based on the FSK carrier signal and the series of pulses; and digitally generating a synchronized constant frequency clock signal from the carrier frequencies based on the digital data transfer protocol and the series of pulses.
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Specification