The effect of collector location on βuof I2L structures

I²L multicollector n-p-n transistor structures are used widely in LSI chips. Due to layout restrictions the collector could be at a distance from the injector. In this case, βuper collector is affected by the lateral voltage drop in the base. This effect becomes significant at higher current levels. In this work the lateral base region of the n-p-n transistor is modeled and a scheme is given to obtain the variation of βuwith the base current. The results are compared to measurements obtained using a three-collector structure.