Title:
TWOOWIRE TYPE TRANSMITTER
Document Type and Number:
Japanese Patent JPS55121510
Kind Code:
A
Abstract:
PURPOSE:To obtain a constant current circuit which has temperature characteristics and small output deviation by flowing a current through a reference resistance in proportion to a reference voltage by using a bipolar transistor, and then by using its voltage drop as the reference voltage of the constant current circuit. CONSTITUTION:The constant current circuit consisting of transistor Q1 and resistance R1 is provided with its reference voltage from the circuit of diode-connected transistor D1 and R0. This reference voltage circuit is supplied with constant current Is by transistor Q2 and resistance R2. This operating current Is is determined by the characteristic of reference voltage Z1, and the operating current of a measuring circuit M can be designed to be a small constant current, so that the temperature coefficient of the voltage of reference voltage source Z1 can extremely be small. In this constitution, operating current Is and output current Ix of the constant current circuit both obtain small temperature coefficients.
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Inventors:
OKAYAMA TSUTOMU
KATOUGI KATSUYA
KATOUGI KATSUYA
Application Number:
JP2870979A
Publication Date:
September 18, 1980
Filing Date:
March 14, 1979
Export Citation:
Assignee:
HITACHI LTD
International Classes:
H04B3/50; G05F1/56; G05F3/26; H04B3/44; (IPC1-7): G05F1/56; H04B3/44
Domestic Patent References:
| JPS50343A | 1975-01-06 |