Current mirror circuit and reference voltage generating and light emitting element driving circuits using the same
First Claim
1. A current mirror circuit composed of a plurality of n-FETs having identical characteristics, said current mirror circuit comprising:
- a first FET pair in which respective sources and gates of two pieces of said n-FETs are connected to each other in a crossing manner, a higher-potential side power supply being connected to drains of both of said two pieces; and
a second FET pair composed of two pieces of said n-FETs different from said first FET pair, whose respective sources and gates are connected to each other in a crossing manner, one of said n-FETs having a drain connected to the source of one of the FETs constituting said first FET pair, the other n-FET having a drain connected to said higher-potential side power supply;
wherein the other n-FET of said first FET pair and the other n-FET of said second FET pair have source output currents identical to each other.
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Accused Products
Abstract
A plurality of n-channel FETs in predetermined combinations are grouped two by two into pairs, and their respective gates and sources are connected to each other in a crossing manner, thus forming a first current mirror circuit connected to a higher-potential side power supply. A second current mirror circuit constituted by another plurality of n-channel FETs, diodes, and a variable resistor, which is connected to a lower-potential side power supply, is connected to the first current mirror circuit connected to the higher-potential side power supply, thereby forming a reference voltage generating circuit which generates a constant voltage. Further, three other pieces of n-channel FETs biased by this constant voltage, a diode, and the like constitute a light emitting element driving circuit for driving a light emitting element.
225 Citations
10 Claims
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1. A current mirror circuit composed of a plurality of n-FETs having identical characteristics, said current mirror circuit comprising:
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a first FET pair in which respective sources and gates of two pieces of said n-FETs are connected to each other in a crossing manner, a higher-potential side power supply being connected to drains of both of said two pieces; and a second FET pair composed of two pieces of said n-FETs different from said first FET pair, whose respective sources and gates are connected to each other in a crossing manner, one of said n-FETs having a drain connected to the source of one of the FETs constituting said first FET pair, the other n-FET having a drain connected to said higher-potential side power supply; wherein the other n-FET of said first FET pair and the other n-FET of said second FET pair have source output currents identical to each other. - View Dependent Claims (2)
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3. A current mirror circuit including 2×
- m sets (m being a natural number not smaller than
2) of FET pairs each combining together two pieces of a plurality of n-FETs having identical characteristics such that respective sources and gates thereof are connected to each other in a crossing manner;m sets of the FET pairs constituting each of first and second groups of FET pair series; each of the n-FETs in said first group of FET pair series having a drain connected to a higher-potential side power supply; whereas, in said second group of FET pair series, a first n-FET of an i-th (1≦
i≦
m-1) set of FET pair having a drain connected to the source of a second n-FET of the i-th set of FET pair in said first group of FET pair series, the second n-FET thereof having a drain connected to the source of the first n-FET of an (i+1)-th set of FET pair in said first group of FET pair series,the first n-FET of an m-th set of FET pair having a drain connected to the source of the second n-FET of the m-th set of FET pair in said first group of FET pair series, the second n-FET thereof having a drain connected to the source of the first n-FET of the first set of FET pair in said first group of FET pair series, thus forming a circular path; wherein all of the m pieces of the first n-FETs in said second group of FET pair series have source output currents identical to each other, and all of the m pieces of said second n-FETs in said second group of FET pair series have source output currents identical to each other. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10)
- m sets (m being a natural number not smaller than
Specification