Flash memory with improved erasability and its circuitry

摘要

A negative-voltage bias circuit is provided which comprises: a capacitor (550) having first and second terminals (550B, 550A) ; a first p-channel MIS field-effect transistor (551) whose drain is connected to a negative-voltage output terminal (554) and whose gate and source are connected to the first terminal (550B) of the capacitor (550); and a second p-channel MIS field-effect transistor (552) whose drain is connected to the source of the first p-channel MIS field effect transistor (551), whose gate is connected to the negative-voltage output terminal (554), and whose source is provided with a negative voltage (VBB). The first p-channel MIS field-effect transistor (551) is a depletion-type p-channel MIS field-effect transistor. In operation of the circuit, application to the second terminal (550A) of a series of clock pulses (CLK) causes a potential of the negative-voltage output terminal (554) to tend towards the negative voltage (VBB).