Abstract: Disclosed herein is a sense amplifier circuit which includes a first, a second and a third similar load transistors. The first and second load transistors supply a dummy data line with a current of the same amount to one another. Acting in a current mirror configuration, the third load transistor supplies a data line with a current equaling the total current supplied by the first and second load transistors. A dummy memory cell is composed of the same transistor as an on-state memory cell. According to this sense amplifier structure, it is very easy to obtain a dummy cell current which has an intermediate value consistently between an on cell current and an off cell current of the memory cell, which are supplied from the third load transistor to the data line. The improved intermediate value yields a reliable readout of the memory cell.

Abstract: Disclosed is a nonvolatile semiconductor memory device which comprises a mode register for storing the data for controlling plural operating modes, for instance, the RAS and the CAS latency, the burst length, and the burst type, of the memory device. The mode register of the present invention comprises a plurality of programmable elements, and a default value of the mode register is set depending on whether or the programmable elements are programmed. Furthermore, each of the programmable elements is comprised of the same element as the memory cells of the memory device. With the present invention, various default values for the mode register are set in accordance with the user's requirement without an additional process step.

Abstract: A sense amplifier circuit includes a first voltage-controlled current source to supply current proportional to a first bias voltage to a reference node and a second voltage-controlled current source to supply current proportional to a second bias voltage to a sensing node. The first and second bias voltages are internally generated in response to an externally applied sense amp control signal. A current mirror circuit is also provided for the sense amplifier circuit. The current mirror circuit commonly deliver current proportional to the voltage level of the reference node to the reference and sensing nodes. A differential amplifier amplifies a difference voltage between reference and sensing nodes.

Abstract: A mask ROM of the invention discharges bit lines selectively before a bit line precharge operation in response to an externally applied command. A column decoder selects one of bit lines in response to column select signals. A discharge control circuit generates a first discharge control signal in response to the command. A discharge predecoder generates a plurality of second discharge control signals by logically combining the first discharge control signal with the column select signals. A bit line discharge circuit selectively discharges the bit lines in response to the second discharge control signals. The mask ROM is free from bit line coupling due to the selection of particular memory cells, the cell selection sequence and the programmed states of the selected cells, leading to an improvement in read speed.

Abstract: The present invention provides a redundancy circuit in a semiconductor memory device which has spare memory cells which can store information that can be substituted for data of defective memory cells after the completion of the manufacturing process. If addresses designating the defective memory cells are externally input, the redundancy circuit generates a defective cell relief address signal which corresponds to the address designating the defective memory cell and is used to prevent defective data stored in normal memory cells from being output and causes correction data, to be substituted for the defective data output in correspondence with the defective cell relief address.

Abstract: A semiconductor memory includes a plurality of main bit lines led to sense amplifiers and arranged in a row, direction, a first group of sub bit lines interposed between the memory banks and connected to the main bit lines through a first group of selection transistors, and a second group of sub bit lines interposed between the memory banks and the first group of sub bit lines and connected to a common ground line through a second group of selection transistors.

Abstract: A sense amplifier increases the differential voltage between a reference signal and a sense signal by using a current mirror to control the generation of the reference signal and the sense signal responsive to a common control signal. The sense amplifier includes a reference signal generator for generating the reference signal at a reference node responsive to a reference cell, a sense signal generator for generating the sense signal at a sense node responsive to the state of a memory cell, and a differential amplifier for amplifying the voltage difference between the reference signal and the sense signal. The reference node is coupled to the reference cell which discharges current from the reference node, and the sense node is coupled to the memory cell which discharges current from the sense node. The reference signal generator includes a first current source transistor that is coupled between a power supply terminal and the reference node.

Abstract: A charge-pumping circuit of a semiconductor memory device for generating a voltage higher than an applied supply voltage, including a first MOS transistor having gate and drain terminals through which the supply voltage is received and a source terminal through which an initial voltage is provided to a first node; a first capacitor with predetermined capacitance having one plate connected to the first node and the other plate through which an applied first oscillating signal is received; a third MOS transistor having gate and source terminals connected to the first node to introduce the electric current of the first node into its drain terminal; a second capacitor with capacitance lower than that of the first capacitor, having one plate connected to the second node that is the drain terminal of the third MOS transistor and the other plate through which an applied second oscillating signal is received; and a second MOS transistor having drain and gate terminals connected to the first node and the second node e