Signal amplification circuit for amplifying and sensing current difference and semiconductor memory device including same

A semiconductor memory device comprising:

• a plurality of memory cells through one of which a current amount in accordance with the level of storage data is made to flow at the time of data read out;
• a reference memory cell through which a current amount which becomes the reference for said data read out is made to flow;
• a selection part for electrically connecting one of said plurality of memory cells selected as an objective of the data read out and said reference memory cell to first and second sense input nodes, respectively, at the time of said data read out;
• and
• a sense. amplifier circuit for amplifying and sensing the difference between an input current and a reference current which flow through said first and second sense input nodes, respectively, wherein said sense amplifier circuit includes:
• a reference voltage generation part for generating a reference voltage at a first node in accordance with said reference current;
• a first transistor of a first conductive type, which is electrically connected between a first power supply node that supplies a first voltage and said first input node, for allowing said input current to pass;
• and
• a current comparison part for generating a voltage in accordance with the difference between said input current and said reference current at a second node based on said reference voltage, wherein
• said current comparison part has:
• a second transistor of said first conductive type which is electrically connected between said first power supply node and said second node and which forms a current mirror with said first transistor;
• and
• a third transistor of a second conductive type which is the opposite conductive type to said first conductive type, which has a control electrode for receiving an input of said reference voltage and which is electrically connected between a second power supply node that supplies a second voltage and said second node, wherein
• said sense amplifier circuit further includes an output level setting part for outputting read out data which has a voltage corresponding to a sensing result at an output node in accordance with a voltage of said second node, wherein
• said output level setting part has
• a fourth transistor of said first conductive type which is electrically connected between said first power supply node and said output node and which has a control electrode for receiving an input of a voltage in accordance with said reference voltage and
• a fifth transistor of said second conductive type which is electrically connected between said output node and said second power supply node and which has a control electrode connected to said second node, wherein
• currents which flow through said fourth and fifth transistors, respectively, are in balance under the condition where said input current and said reference current are equal.