Temperature independent current source

Details Temperature independent current source Temperature independent current source

1993-08-13

1995-03-28

Stephan, Steven L.

Electricity: power supply or regulation systems

Self-regulating

Using a three or more terminal semiconductive device as the...

G05F 316, G05F 320

Patent

active

054020611

ABSTRACT:
An improvement is provided for current sources of the type having three transistors configured as follows: The bases of the first (Q1) and second (Q2) transistors are tied together. The collector of the first transistor (Q1) is coupled to a first voltage (V.sub.CC,V.sub.EE) via a first resistor (R1). The emitter of the first transistor (Q1) is coupled to a second voltage (V.sub.EE,V.sub.CC) via a second resistor (R2). The collector of the second transistor (Q2) produces the output current (I.sub.OUT). The emitter of the second transistor (Q2) is coupled to the second voltage (V.sub.EE,V.sub.CC) via a third resistor (R3). The base of the third transistor (Q3) is coupled, either directly or indirectly through a fourth transistor (Q4), to the collector of the first transistor (Q1). The collector of the third transistor (Q3) is connected to the first voltage (V.sub.CC,V.sub.EE) and the emitter of that transistor (Q3) is connected to the bases of the first (Q1) and second (Q2) transistors. The improvement consists of a fourth resistor (R5) coupled between the base and the emitter of the first transistor (Q1), the fourth transistor preferably having a value that is one half of the value of the first resistor (R1) when no fourth transistor (Q4) is present and having a value that is equal to the value of the first resistor (R1) when a fourth transistor (Q4) is in the base path of the third transistor (Q3).

REFERENCES:
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patent: 4460865 (1984-07-01), Bynum et al.
patent: 4590419 (1986-05-01), Moriarty
patent: 4603291 (1986-07-01), Nelson
patent: 4714872 (1987-12-01), Traa
patent: 4786856 (1988-11-01), Metcalf et al.
patent: 4792748 (1988-12-01), Thomas et al.
patent: 4882533 (1989-11-01), Kelley
patent: 5263713 (1993-11-01), Agiman

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