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US 2002/0000876 A1Published application
FSK signal demodulating integration-discharge circuit
AssigneeGeneral Research of Electronics, Inc.
InventorKazuo Kawai
Life of this patent
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AssigneeGeneral Research of Electronics, Inc.
InventorKazuo Kawai
Estimating the term…
A FSK signal demodulating integration-discharge circuit is realized with simple circuit configuration in such a way as to utilize AC waveform itself of the FSK signal as a control signal of a transistor gate. Conversion is made to execute in terms of FSK signals into rectangular-wave signals by the use of a limiter LIM, before adding the rectangular-wave signal to an integrating capacitor C1 through a resistor. Since the capacitor C1 is connected to a first transistor in parallel thereto and being turned ON/OFF due to the rectangular-wave signal, it causes the above capacitor C1 to be charged by the voltage corresponding to time length of half cycle of a portion of positive voltage of the rectangular-wave signal, while it causes the above capacitor C1 to discharge in terms of charged electric charge of the capacitor C1 by the voltage corresponding to time length of half cycle of a portion of negative voltage of the rectangular-wave signal. Charged voltage of the capacitor is also charged into a holding capacitor C2 through a second transistor. The second transistor is turned ON/OFF by the rectangular-wave signal, therefore, the holding capacitor C2 is charged at the same tome the capacitor C1 is charged at the portion of positive voltage, while at the next portion of negative voltage, the holding capacitor C2 is separated from the capacitor C1, thus the capacitor C1 discharge, while the holding capacitor C2 holds charged voltage. According to this operation, it is possible to obtain a hold voltage that is approximately inversely proportional to the frequency of the FSK signal.
A FSK signal demodulating integration-discharge circuit comprising:
A FSK signal demodulating integration-discharge circuit comprising:
Dependencies are inferred from the claim text.