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Patent Searching and Data


Title:
AUTOMATIC FREQUENCY CONTROLLER
Document Type and Number:
Japanese Patent JPH10163756
Kind Code:
A
Abstract:

To compensate an oscillation frequency even if frequency shift width is large at the time of frequency modulation and a carrier frequency is high by negative-feeding back the difference of the output signal of a detector when the positive maximum frequency of the output signal of a voltage control oscillator shifts and a negative maximum frequency shifts.

A differentiation circuit 13 differentiates a clock signal (h) and a rise detection circuit 14 and a fall detection circuit 15 detect the rise and the fall of the clock signal. Sampling pulses (e) and (g) at the timing are added to first and second sample-and-hold circuits 6 and 7. The detection output signal (c) of the detector 4 is sampled/held and sample-holding signals (d) and (f) are inputted to a differential amplifier 8 so as to obtain the difference. The difference is overlapped with an input modulation signal (a) through a loop filter 9 and an adder 10 and it is added to the voltage oscillator 1 as the error signal. Thus, the center frequency of the voltage control oscillator 1 is controlled in a direction where the error signal becomes zero.


Inventors:
HACHITSUKA HIROYUKI
Application Number:
JP1996000317234
Publication Date:
June 19, 1998
Filing Date:
November 28, 1996
Export Citation:
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Assignee:
FUJITSU LTD
International Classes:
G01S7/28; G01S13/34; H03C3/00; H03C3/04; H03J7/04; H03L7/06; (IPC1-7): H03C3/00; G01S7/28; G01S13/34; H03C3/04; H03L7/06
Attorney, Agent or Firm:
柏谷 昭司 (外2名)