# Vgs when vds reaches vgs vta the channel vanishes at

This preview shows page 1. Sign up to view the full content.

This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: es at y = L and the current holds steady at its saturation value. iD (vGS ,v DS ,v BS ) = 1 W * me Cox {vGS - VT (v BS )} 2 2a L vDS Clif Fonstad, 10/03 Lecture 12 - Slide 2 The gradual channel approximation - review cont. The full result is: Valid for v BS 0, and v DS 0 : iG (vGS ,v DS ,v BS ) = 0 and iB (vGS ,v DS ,v BS ) = 0 1 0 for [vGS - VT (v BS )] < 0 < v DS a 1 W 1 2 * iD (vGS ,v DS ,v BS ) = me Cox [vGS - VT (v BS )] for 0 < [vGS - VT (v BS )] < v DS 2a L a 1 W m C * v - V (v ) - a v DS v GS DS for 0 < v DS < [vGS - VT (v BS )] T BS L e ox 2 a with C* eox t ox ox The threshold voltage is written several different ways (all equivalent, of course) 1/ 2 1 VT (v BS ) VFB - 2f p-Si + g 2f p-Si - v BS with g * [2eSiqN A ] 1/ 2 Cox 1/ 2 1/ 2 1/ 2 = VFB - 2f p-Si + g 2f p-Si + g 2f p-Si - v BS - 2f p-Si [ [ = VT (0) + g {[ 2f p-Si - v BS ] {[ [ } 1/ 2 - 2f p-Si [ 1/ 2 } with VT (0) VFB - 2f p-Si + g 2f p-Si [ 1/ 2 The factor a is typically not included in the model because it is approximately 1 and contributes little to the accuracy or to our intuition and insight. Clif Fonstad, 10/03 Lecture 13 - Slide 3 MOSFET Characteristics (n-channel) Also: iG 0 iB 0 K = (W/...
View Full Document

## This note was uploaded on 07/20/2009 for the course CSAIL 6.012 taught by Professor Prof.cliftonfonstadjr. during the Fall '03 term at MIT.

Ask a homework question - tutors are online