Precise characterization of long-distance mismatch of CMOS devices

A new test structure is presented for the characterization of long-distance mismatch of complimentary metal-oxide-semiconductor (CMOS) devices. A single circuit is used to characterize both transistors and resistors. High resolution is achieved by applying a four-terminal method with regulated reference potential to compensate for parasitic resistance effects. Measured data are presented for 0.5-, 0.35-, and 0.25-μm CMOS processes to demonstrate the performance of this approach. In particular, the long distance matching behavior is compared to that of neighboring devices. Examples for linear and nonlinear distance dependencies are shown. The long-distance mismatch has to be taken into account in circuit designs with short channel transistors and with narrow resistors