A Digital Trimming Circuit with Pre-Trimming Function

In order to solve the problems that conventional digital trimming circuits are unable to predict the trimming result after the fuse is melted and that the actual trimming value deviates from the expected trimming value, a digital trimming circuit with a pre-trimming function is proposed. The circuit is based on the idea of pin multiplexing, and the trim signal is input through the function pins of the chip. By controlling the digital trimming circuit to simulate the trimming result after the polysilicon fuses are melted, the optimal trimming scheme is determined. The pre-trimming design improves the accuracy of the trimming. The design of the ending fuse can avoid the problem of false trimming caused by input signal fluctuation during normal operation of the circuit. The circuit is realized based on a 0.18 μm 30V BCD (Bipolar-CMOS-DMOS) process. Simulation results show that the design is able to meet the design expectations.