Analytical transient response of MOS current mirrors

✍ Scribed by Ayman Kayssi

• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: English
• Weight: 130 KB
• Volume: 31
• Category: Article
• ISSN: 0098-9886
• DOI: 10.1002/cta.244

✦ Synopsis

Abstract

The analytical transient response of MOS current mirrors is derived for the case when the input current is a saturating ramp. The closed form solution obtained for the voltages and currents in the circuit is expressed using Airy's functions. The settling time is then calculated using the closed‐form current equation. For the case when the settling time is greater than the transition time of the input current, a closed form solution is obtained. When the settling time is less than the input transition time, a very simple fitting function is found to accurately model the dependence of the settling time on the various parameters in the circuit, including the transition time of the input current. Simulations show excellent agreement of the estimates of the settling time macromodel with LEVEL‐1 SPICE results. For LEVEL‐3 MOSFET models, the error in the macromodel is within 20% of detailed circuit simulation. Copyright © 2003 John Wiley & Sons, Ltd.