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Contents
6.2.1 Intrinsic Charges and Capacitances .................................. 227
6.2.2 Meyer Model ......................................................................... 229
6.2.2.1 Strong Inversion ................................................... 231
6.2.2.2 Weak Inversion .....................................................234
6.2.3 Limitations of Meyer Model ............................................... 236
6.3 Charge-Based Capacitance Model .................................................. 237
6.3.1 Long Channel Charge Model ............................................. 241
6.3.1.1 Strong Inversion ................................................... 241
6.3.1.2 Weak Inversion ..................................................... 244
6.3.1.3 Accumulation ........................................................ 246
6.3.2 Long Channel Capacitance Model .................................... 246
6.3.3 Short Channel Charge Model ............................................ 248
6.3.4 Short Channel Capacitance Model .................................... 250
6.4 Gate Overlap Capacitance Model ................................................... 251
6.5 Limitations of the Quasistatic Model .............................................254
6.6 S/D pn-Junction Capacitance Model .............................................. 256
6.6.1 Source-Body pn-Junction Diode ......................................... 256
6.6.2 Drain-Body Junction Diode ................................................ 257
6.7 Summary ............................................................................................ 258
Exercises ........................................................................................................ 259
7. Compact MOSFET Models for RF Applications .................................. 261
7.1 Introduction ....................................................................................... 261
7.2 MOSFET Noise Models .................................................................... 261
7.2.1 Fundamental Sources of Noise .......................................... 262
7.2.2 Thermal Noise ...................................................................... 262
7.2.2.1 Physical Mechanism of Thermal Noise ............ 262
7.2.2.2 Thermal Noise Model .......................................... 264
7.2.3 Flicker Noise ......................................................................... 266
7.2.3.1 Physical Mechanism of Flicker Noise ............... 266
7.2.3.2 Flicker Noise Model ............................................. 266
7.3 NQS Effect .......................................................................................... 274
7.3.1 Modeling NQS Effect in MOSFETs ................................... 275
7.4 Modeling Parasitic Elements for RF Applications........................ 279
7.4.1 Modeling Gate Resistance .................................................. 279
7.4.2 Modeling Substrate Network ............................................. 282
7.4.3 MOSFET RF Model for GHz Applications ....................... 283
7.5 Summary ............................................................................................ 283
Exercises ........................................................................................................284
8. Modeling Process Variability in Scaled MOSFETs ............................. 285
8.1 Introduction ....................................................................................... 285
8.2 Sources of Front-End Process Variability ...................................... 286
8.2.1 Systematic or Global Process Variability .......................... 286