Title:
PHASE COMPARATOR CIRCUIT
Document Type and Number:
Japanese Patent JP3232560
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To compensate a current error between a reference current and an output current and to operate this circuit even with a low voltage by providing a 3rd transistor and a constant current source between the collector of a 1st transistor and the base of a 2nd transistor.
SOLUTION: A 3rd NPN transistor Q3 and a constant current source 20 are arranged between the collector of a 1st PNP transistor Q1 and the base of a 2nd PNP transistor Q2. Since voltage VBE between the base and emitter of the transistor Q3 consequently reduces by one stage, VCC can be reduced for it. Also, this circuit can be operated with a low voltage while compensating an offset current between a reference current and an output current. Further, emitter potential can be maintained to a prescribed value by connecting a resistance to the emitter of either the transistor Q1 or the transistor Q2, and the variation of an emitter current due to a manufacturing process can be reduced.
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Inventors:
Naohiro Matsui
Application Number:
JP1272899A
Publication Date:
November 26, 2001
Filing Date:
January 21, 1999
Export Citation:
Assignee:
NEC
International Classes:
G01R25/00; H03D13/00; H03F3/30; H03F3/343; H03L7/085; G05F3/26; (IPC1-7): H03D13/00; G01R25/00; H03F3/343; H03L7/085
Domestic Patent References:
| JP6112106A | ||||
| JP57206107A | ||||
| JP9298429A | ||||
| JP11145740A |
Attorney, Agent or Firm:
Hiroshi Amano