Ute Kollmer

On the matching behavior of MOSFET small signal parameters

An array test structure for precise characterization of the matching behavior of MOSFETs is presented. Besides the standard mismatch parameter drain current I/sub D/, the high resolution measurement principle allows the characterization of the small signal parameters transconductance g/sub m/ and in particular differential output conductance g/sub DS/. Measured data are shown to demonstrate the performance of the method. Whereas for the normalized standard deviations of I/sub D/ and g/sub m/ the well known proportionality to (WL)/sup -1/2/ is obtained, the normalized standard deviation of g/sub DS/ clearly deviates from this width and length dependence. For this parameter, proportionality to W/sup -1/2/ is found.

A new test circuit for the matching characterization of npn bipolar transistors

A new test macro with an active device array is presented for the mismatch characterization of npn bipolar transistors. The macro contains a CMOS circuit which serves for the selection of each bipolar device individually. For each bipolar device terminal a force/sense method is employed to assure the high voltage accuracy requested for bipolar transistors. The characterization of the array with transistors of different geometry gives a database on chip level for the statistical analysis. Matching parameters are given for collector current, current gain, and base-emitter voltage of a 0.5 /spl mu/m smart power technology. The results agree well with in-line measurements using single device pairs and are comparable to reported values in the literature for corresponding technologies.

Mismatch of MOSFET small signal parameters under analog operation

The matching behavior of drain current I/sub D/ and small signal parameters transconductance g/sub m/ and differential output conductance g/sub DS/ of MOSFETs is investigated under typical analog operating conditions. Whereas for the normalized standard deviations of I/sub D/ and g/sub m/ the well known proportionality to (W/spl times/L/sub eff/)/sup -1/2/ is obtained, the normalized standard deviation of g/sub DS/ clearly deviates from this width and length dependence. For this parameter, a proportionality to W/sup -1/2/ is found.