Patent ID: 6654304
Filing Date: 2003-11-25
Classification: G11C

Abstract:
A poly fuse trim cell, comprising:a poly fuse having intact and open states, said poly fuse capable of being opened by conducting a first current through it, a first transistor, the current circuit of which is connected in series with said fuse at a first node, said first transistor arranged to conduct said first current and thereby open said poly fuse in response to a control signal, a current source circuit which provides a second current, a switching transistor, the current circuit of which is connected between said first node and said current source circuit such that the voltage at said first node is pulled to a known value by said second current when said fuse is open and said switching transistor is on, and such that said trim cell draws negligible current when said switching transistor is off, and a logic gate connected to said first node at one input and to a reset signal at a second input, said reset signal having nominal and reset states, said logic gate arranged to toggle its output from a first state to a second state if said first node is pulled to said known value or if said reset signal is in said reset state, said logic gate's output connected to control said switching transistor, said logic gate and said switching transistor arranged such that said switching transistor is turned on when said logic gate's output is in said second state.