A Dynamic Bias Current Technique for a Bipolar Exponential–Law Element and a CMOS Square–Law Element Usable with Low Supply Voltage

Katsuji KIMURA  

Publication
IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E77-A   No.11   pp.1922-1928
Publication Date: 1994/11/25
Online ISSN: 
DOI: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section LETTER (Special Section of Letters Selected from the 1994 IEICE Spring Conference)
Category: 
Keyword: 
exponential–law,  square–law,  bipolar,  CMOS,  hyperbolic function,  OTA,  squaring circuit,  

Full Text: PDF>>
Buy this Article




Summary: 
An emitter–coupled pair with a dynamic bias current and a source–coupled pair with a dynamic bias current are proposed as an exponential–law element and a square–law element that operate as a floating bipolar junction transistor (BJT) and a floating MOS field–effect transistor (MOSFET). In bipolar technology, a hyperbolic sine function circuit and a hyperbolic cosine function circuit are easily obtained by subtracting and summing the output currents of two symmetrical exponential–law elements with positive and negative input signals. In the same manner, an operational transconductance amplifier (OTA) and a squaring circuit are obtained by subtracting and summing the output currents of two symmetrical square-law elements with positive and negative input signals in CMOS technology. The proposed OTA and squaring circuit possess the widest input voltage range ever reported.