A fast and accurate way of evaluating the Widlar current using the Newton–Raphson method

Abstract

Abstract The Widlar current source is one of the basic current sources that undergraduate students encounter throughout their learning process on electronics courses. The Widlar current is actually given in terms of a transcendental equation. Although an analytical solution exists in terms of the Lambert W function it might not be that useful for students during exams or other practical applications. This paper presents a fast and accurate way to solve the problem numerically using the Newton–Raphson method with a regular scientific calculator, and compares the results with the analytical solution given by the Lambert W function.