Semiconductor device including a test circuit of a multivalued logic circuit having an impedance control

Abstract

A semiconductor device, having an input terminal configured to receive a multi-valued input signal as input, the multi-valued input signal including a plurality of values, a multi-valued logic circuit that operates with a multi-valued function and output binary signals to an output section in response to the input signal that has been input to the input terminal, the output section having a number of nodes being one less than a number of the plurality of values of the multi-valued input signal, and an impedance control circuit that is connected to the input terminal and the output section, and changes a combined resistance value in response to the binary signals of the plurality of nodes to change a current which flows in the input terminal.

1 . A semiconductor device, comprising:
 an input terminal configured to receive a multi-valued input signal as input, the multi-valued input signal including a plurality of values;   a multi-valued logic circuit that operate with a multi-valued function and output binary signals to an output section in response to the multi-valued input signal that has been input to the input terminal, the output section including a number of nodes being one less than a number of the plurality of values of the multi-valued input signal; and   an impedance control circuit that is connected to the input terminal and the output section, and changes a combined resistance value in response to the binary signals of the nodes to change a current which flows in the input terminal.   
     
     
         2 . The semiconductor device according to  claim 1 , wherein the impedance control circuit includes a plurality of impedance switch circuits connected in parallel between the input terminal and a reference potential. 
     
     
         3 . The semiconductor device according to  claim 2 , wherein control terminals of the impedance switch circuits are connected to the nodes, respectively, and
 wherein the impedance switch circuits conduct switching operation in response to the output signals.   
     
     
         4 . The semiconductor device according to  claim 2 , wherein the impedance switch circuits each include a switching element and a resistor. 
     
     
         5 . A semiconductor device, comprising:
 an input terminal configured to receive a multi-valued input signal as input, the multi-valued input signal including a plurality of values;   a comparator circuit that operates according to at least one reference voltage in response to the input signal that has been input to the input terminal for output to an output terminal having a node number being one less than a number of the plurality of values of the multi-valued input signal; and   an impedance control circuit that is connected to the input terminal and the output terminal, and changes a current which flows in the input terminal.   
     
     
         6 . The semiconductor device according to  claim 5 , wherein the impedance control circuit changes a combined resistance value in response to binary signals of the output terminal to change a current which flows in the input terminal, and
 wherein the impedance control circuit includes impedance switch circuits connected in parallel between the input terminal and a reference potential.   
     
     
         7 . The semiconductor device according to  claim 6 , wherein control terminals of the impedance switch circuits are connected to at least a node of the node number, respectively, and
 wherein the impedance switch circuits conduct switching operation in response to the output signals.   
     
     
         8 . The semiconductor device according to  claim 6 , wherein the impedance switch circuits each include a switching element and a resistor. 
     
     
         9 . A semiconductor device, comprising:
 an input terminal configured to receive an input signal as input;   a comparator circuit that operates according to at least one reference voltage in response to the input signal that has been input to the input terminal; and   an impedance control circuit that is connected to the input terminal and an output of the comparator circuit, and changes a current which flows in the input terminal.   
     
     
         10 . The semiconductor device according to  claim 9 , wherein the impedance control circuit includes impedance switch circuits that are connected in parallel between the input terminal and a reference potential. 
     
     
         11 . The semiconductor device according to  claim 10 ,
 wherein control terminals of the impedance switch circuits are connected to the output, respectively, and   wherein the impedance switch circuits conduct switching operation in response to the output signal of the impedance control circuit.   
     
     
         12 . The semiconductor device according to  claim 10 , wherein the impedance switch circuits each include a switching element and a resistor, the resistor being set in advance to provide a relationship between an input potential applied to the input terminal and the current flowing in the input terminal. 
     
     
         13 . The semiconductor device according to  claim 9 , wherein the impedance control circuit changes a combined resistance value in response to output signal of the impedance control circuit to change a current which flows in the input terminal.