A Novel BJT Structure Implemented Using CMOS Processes for High-Performance Analog Circuit Applications

Abstract

In this paper, a novel bipolar junction transistor (BJT) structure is proposed for high matching characteristics and its performance is compared with a conventional BJT structure. Although the proposed BJT matching structure indicates a decrease of collector current density <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$J_{C}$</tex></formula> and current gain <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\beta$</tex></formula> of about 5.36% and 1.02% compared with those of the conventional BJT structure, the matching characteristics of the collector current <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$(A_{\rm IC})$</tex></formula> and the current gain <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$(A_{\beta})$</tex> </formula> for the proposed structure are improved by about 31% and 24%. The improved matching characteristic of the proposed structure is believed to be due to the reduced effect of the deep n-well or the reduced current path from emitter to collector.