Soft Guard—A Method of Trimming Resistors in Closed Loops
P. Lenk · Hybrid Circuits · 1990
The automatic laser trimming of resistors is highly developed, but some areas of application still allow improvements. The method described is a new development for trimming resistor networks. When resistors within a network have to be trimmed, the influence from the other resistors has to be compensated in order to obtain a correct measurement (e.g, π-network). Normally this is achieved with an Active Guard circuit, but new generation laser trimmers also offer an entirely mathematical compensation called Soft Guard.