Title:
TRIANGULAR WAVE OSCILLATION CIRCUIT AND VIDEO SIGNAL PROCESSOR PROVIDED WITH IT
Document Type and Number:
Japanese Patent JP2758852
Kind Code:
B2
Abstract:
PURPOSE: To obtain a triangular wave oscillation circuit capable of being synchronized with an external clock signal and oscillating the triangular wave with a stable amplitude by providing 1st, 2nd comparators and a flip-flop and controlling the charge/ discharge of a capacitor from a current source in response to an output of the flip-flop.
CONSTITUTION: This circuit includes a charge discharge circuit 81 selecting charging or discharging so as to provide an output of a triangular wave voltage, a reference voltage switching circuit 82 selecting either of two reference voltages, 1st and 2nd comparators 83, 84, and a flip-flop 85 controlling the charge discharge circuit 81 in response to an output of the comparators 83, 84. Through the constitution above, a switching transistor(TR) 104 controlling the reference voltage switching circuit 82 is conductive for a period when a reference clock is at an H level to decrease a voltage at a connecting point B. Conversely the switching transistor(TR) 104 controlling the reference voltage switching circuit 82 is nonconductive for a period when a reference clock is at an L level to increase the voltage at the connecting point B. Thus, the amplitude of the outputted triangular wave is kept within a range between constant upper and lower levels.
Inventors:
YAMAZAKI KOICHI
Application Number:
JP9042195A
Publication Date:
May 28, 1998
Filing Date:
April 17, 1995
Export Citation:
Assignee:
ROOMU KK
International Classes:
H04N5/63; H02M3/00; H03K4/06; (IPC1-7): H03K4/06; H04N5/63
Domestic Patent References:
| JP548406A | ||||
| JP5762621A | ||||
| JP5432250A | ||||
| JP5098264A |
Attorney, Agent or Firm:
Shizuo Sano
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