Circuit for clamping enable clock in a semiconductor memory device

摘要

A circuit for a clamping an /RAS signal in a DRAM. The bit line pre-charge generator is activated after the set-up of the VBB voltage, so that /RAS signals may be supplied to the chip after the bit line pre-charge voltage (VBLP) has reached the desired level, thereby preventing malfunction of the sense amplifiers. The circuit includes: a VBB sensor for producing VBB set-up signal S1 when a back bias voltage VBB in the semiconductor memory device has reached a desired level; a power-up generator for producing a power-up signal S2 when power in the semiconductor memory device is set-up; a VBLP generator for generating a bit line pre-charge voltage VBLP; a VBLP controller for holding the VBLP voltage to a ground voltage level according to the S1 and S2 signals; a VBLP sensor for generating VBLP set-up signal S3 when the VBLP voltage has reached a desired level; a /RAS pass signal generator for producing a /RAS pass signal S4 according to the S3 and S2 signals; a NOR circuit for controlling the transmission of the /RAS signals according to the S 4 signal.