Current detecting differential amplifier and sram formed by using the same

PURPOSE: To enable cascade connection of plural stages and to eliminate the need for a unification clock signal by providing a current amplifier with a special biasing circuit and applying a low-input impedance and high-output impedance. CONSTITUTION: The current amplifier is provided with the biasing circuit consisting of transistors TrN7, N8 and the gate electrodes thereof are connected to a reference voltage Vref . A data line pull-up circuit uses the TrP7, P8 biased to the linear region as a pull-up element. This pull-up element applies Vcc bias to the amplifier and in addition, the element makes a data line DC common mode voltage higher than the writing voltage to a memory cell. When the Tr load of the linear range is used, the mode voltage falls to the extent that the data line common mode voltage drop makes the value of the resistance larger in proportion to the resistance value of the pull-up element. Then, a linear MOS circuit limits a current gain in order to maintain the mode voltage level. As a result, the cascade connection of the plural stages is made possible.