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Patent Searching and Data


Title:
FREQUENCY MODULATION CIRCUIT
Document Type and Number:
Japanese Patent JPS6016003
Kind Code:
A
Abstract:

PURPOSE: To eliminate the need for a band-pass filter by adding a circuit using Zener diodes connected in series as a voltage limit circuit to a preamplifier so as to limit the change in an output frequency.

CONSTITUTION: The Zener diodes 19, 20 are provided to an output part of the preamplifier, a Zener voltage of the diode 19 is selected as Vc-Vb1 and a Zener voltage of the Zener diode 20 is selected to Vb2. When the base voltage Vb is higher than the voltage Vb2, a current flows to the diode 20 and the base voltage Vb is limited to the voltage Vb2. Since the base voltage Vb is limited between the voltages Vb1 and Vb2 by the diodes 19, 20 in this way, an output frequency Fout is limited also between Fout1 and Fout2. Thus, the maximum frequency of the output frequency of a frequency modulation circuit FM-MOD1 to a frequency F1 is set lower than the minimum frequency of an output frequency of a frequency modulation circuit FM-MOD2 to a frequency F2 and the relation like this is established sequentially.


Inventors:
Watanabe, Masaaki
Odaka, Kazuyuki
Ishikawa, Akira
Application Number:
JP1983000122733
Publication Date:
January 26, 1985
Filing Date:
July 06, 1983
Export Citation:
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Assignee:
FUJITSU LTD
International Classes:
H04J1/02; H03C3/00; H03C3/06; (IPC1-7): H03C3/06; H03C3/00; H04J1/02