PROGRAMMABLE LOGIC DEVICE HAVING A SENSE AMPLIFIER WITH VARYING CAPABILITIES

摘要

A sense amplifier (50) for a programmable logic device comprises a pair of transistors (54, 52) in a feedback configuration between a sense amplifier output (OUT) and a virtual ground (BL GND). A clipping transistor (70) and a current channeling transistor (62) can be provided to the sense amplifier. Further an additional current source (64) and a current sink (72) can be added to the sense amplifier. The clipping transistor helps to ensure that any positive noise spikes do not deteriously affect readings of the value on the input bit line (BL). The current channeling transistor prevents collapse of the bit line caused by significant conductivity of cells connected to the bit line. The combination of clipping and current channeling provides a relatively narrow voltage range of the bit line voltage, resulting in fast recovery and high-speed sensing thereof. The additional current source is used to impute additional current through the amplifying transistor (54). The additional current sink transistor helps to draw current from the amplifying transistor to a ground supply. Only when the bit line voltage is high will the additional voltage sink transistor (72) be used.