VARIABLE RESISTANCE CIRCUIT

Japanese Patent JP3167520

B2

PURPOSE: To obtain a circuit with an excellent attenuation efficiency even in a high frequency region by providing a variable resistor whose input and output terminals are respectively connected and an auxiliary variable resistor whose resistance is a required resistance and whose both terminals are respectively connected to the variable resistor and ground, thereby controlling the resistance to a prescribed value.
CONSTITUTION: N-channel FET TR1 acting like a variable resistor is connected between an input terminal 1 and an output terminal 2, and a series circuit comprising an N-channel FET TR2 whose resistance is inversely proportional to the FET TR1 and a capacitor 22 is connected between a gate of the FET TR1 and ground. Then the circuit is controlled in such a way that the resistance of the FET TR2 is low when the resistance of the FET TR1 is high, and the resistance of the FET TR2 is high when the resistance of the FET TR1 is low through fixed high resistance resistors 12, 13. Thus, a leakage signal caused by a parasitic capacitance when the resistance of the FET TR1 is high is short- circuited, and the FET TR2 blocks the leakage when the resistance of the FET TR1 is low to obtain the variable resistance circuit with an excellent attenuation efficiency even in a high frequency region.

JP2661318	[Title of Invention] Semiconductor device
JPH0738059	ELECTROSTATIC BREAKAGE PROTECTIVE CIRCUIT
JP3119544	SEMICONDUCTOR INTEGRATED CIRCUIT DEVICE

Tsutomu Takenaka

JP1379694A

May 21, 2001

February 07, 1994

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Terra Tech Co., Ltd.

H01L27/04; H01L21/822; H01L29/66; H03H11/24; H03H11/46; (IPC1-7): H03H11/24; H01L21/822; H01L27/04; H01L29/66; H03H11/46

JP63245013A

Naotaka Ide

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