Microelectronics: CMOS Circuits, Device Characteristics, and Applications, Study notes of Electrical and Electronics Engineering

Download Microelectronics: CMOS Circuits, Device Characteristics, and Applications and more Study notes Electrical and Electronics Engineering in PDF only on Docsity! 1 21) Basic CMOS Circuits 21.1 NMOS Device Characteristics VDS VGS ID EEE435/591 Microelectronics Spring 2009 21.2 PMOS Device Characteristics -VDS -VGS ID EEE435/591 Microelectronics Spring 2009 2 21.3 Device Equations We usually describe the MOSFET drain current in one of two regimes: i) Below Saturation [ ]DSDSthGSoxD VVVVL WCI −−= μ 22/1)( ( ) DSthGSox VVVL WC −≈ μ for small VDS ii) Above Saturation ( )2 2 thGS ox D VVL WCI −= μ For circuits we require complementary devices i.e. if a PMOS and NMOS d i h id ti l bi i (b t f it i ) th th d i EEE435/591 Microelectronics Spring 2009 ev ce ave en ca as ng u o oppos e s gn en e same ra n current will flow ⇒ typepth typen th VV −− −= And μn Wn = μp Wp ⇒ Wp ≈ 2Wn because μn~600 cm2/Vs and μp~300 cm2/Vs 21.4 The CMOS Inverter VoutVin EEE435/591 Microelectronics Spring 2009