Frequency-to-current conversion circuit
AssigneeNippondenso Co., Ltd.
InventorsTomoatsu Makino, Yoshio Hirano, Katsuteru Miwa
Life of this patent
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Abstract
A frequency-to-current conversion circuit comprises a charge/discharge circuit for charging or discharging with a first constant current in synchronism with each cycle of an input pulse signal having a varying frequency, a voltage comparison circuit for detecting a predetermined voltage attained by the charge/discharge circuit at the expiration of a predetermined time interval dependent on the value of the first constant current from the beginning of the charge or discharge, and an output circuit for receiving the output signal of the voltage comparison circuit as well as the input pulse signal to generate a second constant current during the predetermined time interval in synchronism with each cycle of the input pulse signal.
Claims10
A frequency-to-current conversion circuit comprising:
- input means for receiving a train of pulse signals;
- current supply means for supplying first and second constant electric currents;
- a capacitor;
- control means for charging said capacitor by said first constant current in response to one of leading and trailing edges of said pulse signals and discharging said capacitor in response to the other of leading and trailing edges of said pulse signals;
- comparison means for comparing charged voltage produced across said capacitor with a predetermined voltage;
- and
- output means for deriving said second constant current during constant intervals of time determined by subjecting said pulse signals and output signals of said comparison means to a logic operation.
Dependencies are inferred from the claim text.