Differential amplifier using a constant-current source circuit

Claim 2

A constant-current source circuit as claimed in claim l, wherein an output current of one of said constant-current source circuit units is controlled by a threshold voltage characteristic of a P-channel MOS transistor or a PNP-type transistor, and an output unit current of the other constant-current source circuit/is controlled by a threshold voltage characteristic of an N-channel MOS transistor or an NPN-type transistor.

Claim 3

A differential amplifier comprising a pair of differential transistors whose sources or emitters are commonly connected, and a constant-current source circuit including: a constant-current source circuit unit having a positive temperature coefficient; a constant-current source circuit unit having a negative temperature coefficient; and a current synthesizing circuit for synthesizing output currents of these constant-current source circuit units.

Claim 4

A differential amplifier as claimed in claim 3, wherein an output current of one of said constant-current source circuit units is controlled by a threshold voltage characteristic of a P-channel MOS transistor or a PNP-type transistor, and an output current of the other constant current source circuit unit is controlled by a threshold voltage characteristic of an N-channel MOS transistor or an NPN-type transistor.

Claim 5

A differential amplifier as claimed in claim 3, wherein said constant-current source circuit comprises: a series connection of a first P-channel MOS transistor (Q 10 ) and a first resistor (R 6 ) coupled between a high-voltage power terminal and a low-voltage power terminal; a series connection of a second resistor (R 5 ) and a second P-channel transistor (Q 9 ) coupled between said high-voltage power terminal and said low-voltage power terminal, the gate of said first P-channel MOS transistor (Q 10 ) being connected to the connection point of said second resistor (R 5 ) and said second P-channel MOS transistor (Q 9 ), the gate of said second P-channel MOS transistor (Q 9 ) being connected to the connection point of said first P-channel MOS transistor (Q 10 ) and said first resistor (R 6 ); a current mirror circuit having a third MOS transistor (Q 8 ) and a fourth MOS transistor (Q 7 ), said third MOS transistor (Q 8 ) being inserted between said second P-channel MOS transistor (Q 9 ) and said low-voltage power terminal, and said fourth MOS transistor (Q 7 ) being inserted between commonly of said pair of differential transistors connected sources and said low voltage power terminal; a series connection of a fifth N-channel MOS transistor (Q 6 ) and a third resistor (R 3 ) coupled between said low-voltage power terminal and said high-voltage power terminal; and of a series connection of a sixth N-channel MOS transistor (Q 5 ) and a fourth resistor (R4) coupled between said commonly connected sourcesand said low-voltage power terminal, the gate of said fifth N-channel MOS transistor (Q 6 ) being connected to the connection point of said fourth resistor (R 4 ) and said sixth N-channel MOS transistor (Q 5 ), the gate of said sixth N-channel MOS transistor (Q 5 ) being connected to the connection point of said fifth N-channel MOS transistor (Q 6 ) and said third resistor (R 3 ).

Claim 6

A differential amplifier as claimed in claim 3, wherein said constant-current source circuit comprises: a series connection of a first PNP-type transistor (Q 18 ) and a first resistor (R 12 ) coupled between a high-voltage power terminal and a low-voltage power terminal; a series connection of a second resistor (R 11 ) and a second PNP-type transistor (Q 17 ) coupled between said high-voltage power terminal and said low-voltage power terminal, the base of said first PNP-type transistor (Q 18 ) being connected to the connection point of said second resistor (R 11 ) and said second PNP-type transistor (Q 17 ), the gate of said second PNP-type transistor (Q 17 ) being connected to the connection point of said first PNP-type transistor (Q 18 ) and said first resistor (R 12 ); a current mirror circuit having a third transistor (Q16) and a fourth transistor (Q 15 ), said third transistor (Q 16 ) being inserted between said second PNP-type transistor (Q 17 ) and said low-voltage power terminal, and said fourth transistor (Q 15 ) being inserted between commonly connected emitters of said pair of differential transistors and said low-voltage power terminal; a series connection of a fifth NPN-type transistor (Q 14 ) and a third resistor (R 9 ) coupled between said low-voltage power terminal and said high-voltage power terminal; and a series connection of a sixth NPN-type transistor (Q 13 ) and a fourth resistor (R 10 ) coupled between said commonly connected emittersand said low-voltage power terminal, the base of said fifth NPN-type transistor (Q 14 ) being connected to the connection point of said fourth resistor (R 10 ) and said sixth NPN-type transistor (Q 13 ), the base of said sixth NPN-type transistor (Q 13 ) being connected to the connection point of said fifth NPN-type transistor (Q 14 ) and said third resistor (R 9 ).

Claim 7

A differential amplifier comprising: a pair of transistors whose drains or collectors are connected to a power terminal via load elements, whose gates or bases receive input signals, and whose sources or emitters are commonly connected; and a constant current source circuit connected to said commonly connected sources or emitters, said constant-current source circuit having the characteristic that the current flowing therethrough increases in accordance with a temperature rise.

Claim 8

A differential amplifier as claimed in claim 7, wherein said constant-current source circuit comprises: a series connection of a first P-channel MOS transistor (Q 10 ) and a first resistor (R 6 ) coupled between a high-voltage power terminal and a low-voltage power terminal; a series connection of a second resistor MOS (R 5 ) and a second P-channel/transistor (Q 9 ) coupled between said high-voltage power terminal and said low-voltage power terminal, the gate of said first P-channel MOS transistor (Q 10 ) being connected to the connection point of said second resistor (R S ) and said second P-channel MOS transistor (Q 9 ), the gate of said second P-channel MOS transistor (Q 9 ) being connected to the connection point of said first P-channel MOS transistor (Q 10 ) and said first resistor (R 6 ); and a current mirror circuit having a third MOS transistor (Q 8 ) and a fourth MOS transistor (Q 7 ), said third MOS transistor (Q S ) being inserted between said second P-channel MOS transistor (Q 9 ) and said low-voltage power terminal, and said fourth MOS transistor (Q 7 ) being inserted between commonly of said pair of transistors connected sources/and said low-voltage power terminal.

Claim 9

A differential amplifier as claimed in claim 7, wherein said constant-current source circuit comprises: a series connection of a first PNP-type transistor (Q 18 ) and a first resistor (R 12 ) coupled between a high-voltage power terminal and a low-voltage power terminal; a series connection of a second resistor (R 11 ) and a second PNP-type transistor (Q 17 ) coupled between said high-voltage power terminal and said low-voltage power terminal, the base of said first PNP-type transistor (Q 18 ) being connected to the connection point of said second resistor (R 11 ) and said second PNP-type transistor (Q 17 ), the gate of said second PNP-type transistor (Q 17 ) being connected to the connection point of said first PNP-type transistor (Q 18 ) and said first resistor (R12); and a current mirror circuit having a third transistor (Q 16 ) and a fourth transistor (Q 15 ), said third transistor (Q 16 ) being inserted between said second PNP-type transistor (Q 17 ) and said low-voltage power terminal, and said fourth transistor (Q 15 ) being inserted between said commonly connected emitters of said pair of transistors and said low-voltage power terminal.

Claim 10

A constant-voltage source circuit comprising: a constant-voltage source circuit unit having a positive temperature coefficient; a constant-voltage source circuit unit having a negative temperature coefficient; and a voltage synthesizing circuit for synthesizing output voltages of the constant-voltage source circuit units.

Claim 11

A constant-current source circuit comprising at least one current control unit, the or each current control unit comprising a current control transistor, the gate or base of which is connected to a control circuit comprising a further transistor arranged so that the voltage of said gate or base of the current control transistor is controlled in dependence upon a threshold voltage of the further transistor.

Claim 12

A constant-current source circuit as claimed in claim 11, comprising two current control units.