A Trim-Free PVT Invariant Current Reference with 0.48% Process Inaccuracy Using V_TH Tracking Approach

The prevalence of MOSFETs in diverse electronic applications highlights their significance. However, the sensitivity of MOSFET threshold voltage to process variation poses a substantial challenge in achieving consistent device performance. This paper proposes a novel approach to overcome this challenge by employing a threshold voltage <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(V_{TH})$</tex> tracking circuit that tracks the variation in <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$V_{TH}$</tex>. Our primary objective is to develop a current reference that remains invariant across process, voltage, and temperature (PVT) variations, eliminating the need for an external trimming circuit. This is achieved by the meticulous integration of V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</inf> tracking circuit, CTAT generator, PTAT generator, and a current adder. By employing this design, a process variation <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\frac{\sigma}{\mu})$</tex> of 0.48%, a temperature coefficient (TC) of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${210}{ppm}/^{\circ} {C}$</tex> ‘ for a temperature range of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$-{40}/^{\circ} {C}$</tex> to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${120}^{\circ} {C}$</tex>, and a line sensitivity of 1.6% is achieved over a voltage range of 1.6V - 3V. The proposed circuit occupies an area of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${0.013}{mm}^{{2}}$</tex>: while consuming power of 56μW at a typical corner of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${27}^{\circ}{C}$</tex> and a supply of 1.8V. The given circuit is implemented in a 180nm CMOS process node with a generated reference current of 61nA.