Analog subcircuit maintenance in mixed-signal CMOS VLSI circuits

A new analog subsystem design approach is presented that can be used to improve the accuracy, reliability, yield, and testability of analog and mixed-signal CMOS ICs. The proposed scheme is a generally applicable design approach that combines hybrid redundancy, direct subcircuit parameter adjustment, and on-chip analog function verification. Improvements are realized in a system-transparent fashion through function block commutation. The cost is a moderate die area increase. Although applicable to any moderately complex analog function, the example analog function used to illustrate this new design approach presented here is the op amp. Experimental data demonstrate the capabilities of this new design approach.