Test Structure for Ic(Vbe) Parameter Determination of Low Voltage Applications

Abstract : The temperature dependence of the IC(VBE) relationship can be characterised by two parameters: EG and XTI. The classical method to extract these parameters consists in a "best fitting" from measured VBE(T) values, using least square algorithm at constant collector current. This method involves an accurate measurement of VBE voltage and an accurate value of the operating temperature. We propose in this paper, a configurable test structure dedicated to the extraction of temperature dependence of IC(VBE) characteristic for BJT designed with bipolar or BiCMOS processes. This allows a direct measurement of die temperature and consequently an accurate measurement of VBE(T). First, the classical extraction method is explained. Then, the implementation techniques of the new method are discussed, the improvement of the design is presented.