Semiconductor integrated circuit, variable gain amplifier, and sensing system

Abstract

A semiconductor integrated circuit includes a first pad provided on one end side of a first resistive element externally provided, a second pad provided on a different end side of the first resistive element, an operation amplifier, a first signal line wired between an output terminal of the operation amplifier and the first pad, a second signal line wired between one input terminal of the operation amplifier and the second pad, a first ESD (Electrostatic Discharge) protection element provided to the first signal line, and a third signal line, through which a voltage signal of the first pad is transmitted, the third signal line being connected to the first pad, and a second switch, which is selectively turned on, the second switch being provided on the third signal line.

What is claimed is: 
     
         1 . A semiconductor integrated circuit comprising:
 a first pad provided on one end side of a first resistive element externally provided;   a second pad provided on a different end side of the first resistive element;   an operation amplifier;   a first signal line wired between an output terminal of the operation amplifier and the first pad:   a second signal line wired between one input terminal of the operation amplifier and the second pad;   a first ESD (Electrostatic Discharge) protection element provided to the first signal line; and   a third signal line, through which a voltage signal of the first pad is transmitted, the third signal line being connected to the first pad; and   a second switch, which is selectively turned on, the second switch being provided on the third signal line.   
     
     
         2 . The semiconductor integrated circuit according to  claim 1 , wherein
 the one input terminal of the operation amplifier is an inverting input terminal,   a reference voltage is supplied to a non-inverting input terminal as a different input terminal of the operation amplifier, and   an input current supplied to the second pad is converted to the voltage signal.   
     
     
         3 . A semiconductor integrated circuit comprising:
 a first pad provided on one end side of a first resistive element externally provided;   a second pad provided on a different end side of the first resistive element;   an operation amplifier;   a first signal line wired between an output terminal of the operation amplifier and the first pad:   a second signal line wired between one input terminal of the operation amplifier and the second pad;   a first ESD (Electrostatic Discharge) protection element provided to the first signal line; and   a third signal line, through which a voltage signal of the first pad is transmitted, the third signal line being connected to the first pad; and   a third switch, which is selectively turned on, the third switch being provided on the second signal line.   
     
     
         4 . The semiconductor integrated circuit according to  claim 3 , wherein
 the one input terminal of the operation amplifier is an inverting input terminal,   an input voltage is supplied to a non-inverting input terminal as a different input terminal of the operation amplifier, and   a reference voltage is supplied to the different end side of each of the plurality of first resistive elements through a second resistive element.   
     
     
         5 . The semiconductor integrated circuit according to  claim 3 , wherein
 the one input terminal of the operation amplifier is an inverting input terminal,   a reference voltage is supplied to a non-inverting input terminal as a different input terminal of the operation amplifier, and   an input voltage is supplied to the different end side of each of the plurality of first resistive elements through a second resistive element.   
     
     
         6 . The semiconductor integrated circuit according to  claim 1 , further comprising a subsequent stage circuit to which a voltage signal of the first pad which is transmitted through the third signal line is supplied. 
     
     
         7 . The semiconductor integrated circuit according to  claim 6 , wherein the subsequent stage circuit is an AD converter. 
     
     
         8 . The semiconductor integrated circuit according to  claim 1 , further comprising a voltage follower provided on the third signal line. 
     
     
         9 . A semiconductor integrated circuit comprising:
 a first pad provided on one end side of a first resistive element externally provided;   a second pad provided on a different end side of the first resistive element;   an operation amplifier;   a first signal line wired between an output terminal of the operation amplifier and the first pad:   a second signal line wired between one input terminal of the operation amplifier and the second pad;   a first ESD (Electrostatic Discharge) protection element provided to the first signal line: and   a third signal line, through which a voltage signal of the first pad is transmitted, the third signal line being connected to the first pad,   a fourth signal line wired between a different input terminal of the operation amplifier and the plurality of pads, respectively;   a plurality of fourth switches provided on the plurality of fourth signal lines, respectively;   a plurality of third signal lines, to which voltage signals of the plurality of pads are transmitted, the plurality of third signal lines being connected to the plurality of pads, respectively; and   a plurality of second switches provided on the plurality of third signal lines, respectively.   
     
     
         10 . A variable gain amplifier comprising:
 the plurality of first resistive elements; and   the semiconductor integrated circuit according to  claim 2 .   
     
     
         11 . A variable gain amplifier comprising:
 the plurality of first resistive elements;   the second resistive element; and   the semiconductor integrated circuit according to  claim 4 .   
     
     
         12 . A variable gain amplifier comprising:
 the plurality of first resistive elements;   the semiconductor integrated circuit according to  claim 5 .   
     
     
         13 . A sensing system comprising:
 a sensor that outputs the input current as a measurement result;   the plurality of first resistive elements; and   the semiconductor integrated circuit according to  claim 2 .   
     
     
         14 . A sensing system comprising:
 a sensor that outputs the input voltage as a measurement result;   the plurality of first resistive elements;   the second resistive element; and   the semiconductor integrated circuit according to  claim 4 .   
     
     
         15 . A sensing system comprising:
 a sensor that outputs the input voltage as a measurement result;   the plurality of first resistive elements;   the second resistive element; and   the semiconductor integrated circuit according to  claim 5 .   
     
     
         16 . The semiconductor integrated circuit according to  claim 1 , wherein the first pad provided on one end side of the first resistive element externally provided from the semiconductor integrated circuit. 
     
     
         17 . A variable gain amplifier comprising:
 the first resistive element externally provided from the semiconductor integrated circuit; and   the semiconductor integrated circuit according to  claim 1 .