Logic circuit module, method for designing a semiconductor integrated circuit using the same, and semiconductor integrated circuit

Abstract

A logic circuit module is used for designing a semiconductor integrated circuit using an FPGA (Field Programmable Gate Array) or a short-term gate array. Provided that a seventh input terminal of the logic circuit module is fixed to the power supply, a third multiplexer always selects the output of a second multiplexer, and a signal selected by the second multiplexer is directly output to a second output terminal. Moreover, an AND circuit always outputs an output signal of a first multiplexer to a first output terminal. Thus, fixing the seventh input terminal to the power supply causes respective logics formed from the first multiplexer and the second multiplexer to be separated by the third multiplexer, allowing for independent representation of the logics. Accordingly, the area efficiency of the logic circuit module is improved, resulting in reduction in size of the semiconductor integrated circuit.

What is claimed is:  
     
         1 . A logic circuit module, characterized in that 
 it comprises a plurality of input terminals, a plurality of output terminals, and a plurality of logic elements provided between the plurality of input terminals and the plurality of output terminals,    the plurality of input terminals are each connected to an external signal line, a power supply or a ground so as to implement a plurality of desired logic functions, and    at least two of the implemented plurality of logic functions are such that a potential state of an output terminal corresponding to one of the logic functions is not affected by a potential state of an input terminal corresponding to the other logic function.    
     
     
         2 . The logic circuit module according to  claim 1 , characterized in that at least one of the plurality of logic elements separates at least two of the implemented plurality of logic functions from each other so as to make the two logic functions independent of each other.  
     
     
         3 . A logic circuit module, characterized in that 
 it comprises first to seventh input terminals, first and second output terminals, and first to third  2 - 1  multiplexers,    the first  2 - 1  multiplexer has its two signal terminals respectively connected to the first and second input terminals, and its selection terminal connected to the third input terminal,    the second  2 - 1  multiplexer has its two signal terminals respectively connected to the fourth and fifth input terminals, and its selection terminal connected to the sixth input terminal,    the third  2 - 1  multiplexer has its two signal terminals respectively connected to signals selected by the first and second  2 - 1  multiplexers, and its selection terminal connected to the seventh input terminal, and    the first output terminal receives a signal selected by the first  2 - 1  multiplexer, and the second output terminal receives a signal selected by the third  2 - 1  multiplexer.    
     
     
         4 . The logic circuit module according to  claim 3 , characterized in that 
 it further comprises a two-input AND circuit,    the AND circuit receives the signal selected by the first  2 - 1  multiplexer, and the seventh input terminal is connected to the AND circuit, and    the first output terminal receives an output signal of the AND circuit.    
     
     
         5 . The logic circuit module according to  claim 1  or  2 , characterized in that the third input terminal serves also as the sixth input terminal.  
     
     
         6 . The logic circuit module according to  claim 3 , characterized in that the first, third, fourth and sixth input terminals are respectively connected to external signal lines, and the second, fifth and seventh input terminals are connected to a power supply, thereby implementing two independent OR logics.  
     
     
         7 . The logic circuit module according to  claim 3  or  4 , characterized in that the first and fourth input terminals are connected to a ground, the seventh input terminal is connected to a power supply, and the second, third, fifth and sixth input terminals are respectively connected to external signal lines, thereby implementing two independent AND logics.  
     
     
         8 . The logic circuit module according to  claim 3  or  4 , characterized in that the first to sixth input terminals are respectively connected to external signal lines, and the seventh input terminal is connected to a power supply, thereby implementing two independent  2 - 1  multiplexer logics.  
     
     
         9 . The logic circuit module according to  claim 4 , characterized in that the first and fifth input terminals are connected to a ground, the second and fourth input terminals are connected to a power supply, the third and sixth input terminals are connected to a common external signal line, and the seventh input terminal is connected to another external signal line so as to form an EX-OR logic and an AND logic each receiving as inputs two signals of the common external signal line and the another external signal line, thereby implementing a half adder.  
     
     
         10 . A semiconductor integrated circuit, characterized in that 
 it comprises four logic circuit modules each implementing the half adder of  claim 9 , and a single logic circuit module implementing the two OR logics of  claim 6 , and    a lower-bit full adder is formed from two of the four logic circuit modules each implementing the half adder and one of the two OR logics implemented by the logic circuit module, and an upper-bit full adder is formed from the other two logic circuit modules each implementing the half adder and the other OR logic implemented by the logic circuit module, thereby implementing a 2-bit full adder.    
     
     
         11 . The logic circuit module according to  claim 3  or  4 , characterized in that 
 the second, fifth and sixth input terminals are respectively connected to external signal lines, the first input terminal is connected to a ground, the seventh input terminal is connected to a power supply, the third input terminal is connected to the second output terminal, and the fourth input terminal is connected to the first output terminal so as to form an AND logic and a  2 - 1  multiplexer that are independent of each other, and  
 an output of the AND logic is connected to one of two signal terminals of the  2 - 1  multiplexer, thereby implementing a storage circuit having a reset function.  
 
     
     
         12 . The logic circuit module according to  claim 3  or  4 , characterized in that 
 the second and seventh input terminals are connected to a power supply, the first, fifth and sixth input terminals are respectively connected to external signal lines, the third input terminal is connected to the second output terminal, and the fourth input terminal is connected to the first output terminal so as to form an OR logic and a  2 - 1  multiplexer that are independent of each other, and  
 an output of the OR logic is connected to a signal terminal of the  2 - 1  multiplexer, thereby implementing a storage circuit having a set function.  
 
     
     
         13 . A method for designing a semiconductor integrated circuit, characterized in that 
 the semiconductor integrated circuit includes a plurality of logic circuit modules of  claim 1 ,  2 ,  3  or  4 , and    the semiconductor integrated circuit conducting a prescribed operation is designed by connecting the input terminals of the logic circuit modules to a power supply or ground, or connecting an input terminal of a logic circuit module to an output terminal of another logic circuit module.    
     
     
         14 . The method according to  claim 13 , characterized by designing the semiconductor integrated circuit conducting the prescribed operation by 
 forming in advance longitudinal and lateral wirings for connecting the input terminals of the logic circuit modules to the power supply or ground, or connecting the input terminals of the logic circuit modules to the output terminals thereof, and a plurality of connecting means for connecting the longitudinal and lateral wirings to each other, and    then programming so as to connect prescribed longitudinal and lateral wirings to each other through a prescribed one of the plurality of connecting means.    
     
     
         15 . A method for designing a semiconductor integrated circuit, characterized by 
 manufacturing the semiconductor integrated circuit with the logic circuit module of  claim 1 ,  2 ,  3  or  4  incorporated therein, and    when necessity for correction of the manufactured semiconductor integrated circuit arises, correcting the semiconductor integrated circuit by connecting a wiring to the incorporated logic circuit module.