초록 ▼

A trim structure having a nominal resistance value can be adjusted to have a higher or lower value by a combination of fuse blowing and zener zapping. In the preferred embodiment a pair of integrated circuit pads are employed in a trim structure along with a pair of back-to-back zener diodes, a fuse

A trim structure having a nominal resistance value can be adjusted to have a higher or lower value by a combination of fuse blowing and zener zapping. In the preferred embodiment a pair of integrated circuit pads are employed in a trim structure along with a pair of back-to-back zener diodes, a fuse link, and four resistors. In its initial state, with both diodes and the fuse link intact, a particular or nominal resistance value is available. Blowing the fuse link alone produces a second or highest resistance value. Shorting, or zapping, one zener diode produces a third higher than nominal but lower than highest resistance value. Shorting, or zapping, the other zener diode produces a fourth, lower than nominal, resistance value. Shorting, or zapping, both zener diodes produces a fifth lowest resistance value. Thus, five different resistance values are available using only two integrated circuit pads. If desired, the five resistance steps can be made linear by properly selecting the resistor values. In addition, one of the circuit pads can be a common power supply terminal so that only one pad need be added to the integrated circuit chip. Two or more such structures can be fabricated with a common pad by the addition of one additional pad for each such structure.

대표청구항 ▼

A multiple trim structure for use in semiconductor integrated circuits and having a nominal output resistance value wherein a trimming operation can either raise or lower said nominal output value, said structure comprising: a plurality of bonding pads; a network of resistance elements coupled betwe

A multiple trim structure for use in semiconductor integrated circuits and having a nominal output resistance value wherein a trimming operation can either raise or lower said nominal output value, said structure comprising: a plurality of bonding pads; a network of resistance elements coupled between a pair of said bonding pads, said network presenting an output resistance value that can be varied by trimming; a combination of zener diode means and fuse element means coupled between said pair of bonding pads and to said network of resistance elements whereby selected ones of said resistance elements can be invoked; means for coupling current pulses to said pair of bonding pads whereby a selected fuse element can be blown so as to remove a short circuit across a portion of said network thereby raising said output resistance; and means for coupling current pulses to said pair of bonding pads whereby a selected zener diode can be zapped so as to add a short circuit across a portion of said network thereby lowering said output resistance.