深圳大学-数字集成电路(中文)第三章

1、Digital Integrated CircuitsDevicesDigital Integrated CircuitsDevicesq定性了解定性了解MOS器件器件q介绍器件的基本公式介绍器件的基本公式q介绍用于手工分析的简单模型介绍用于手工分析的简单模型q介绍用于介绍用于SPICE模拟的器件模型模拟的器件模型q工艺偏差的影响工艺偏差的影响Digital Integrated CircuitsDevicesnppnBASiO2AlABAlAB 一维表示二极管符号IC工艺中PN结截面图Digital Integrated CircuitsDeviceshole diffusionelectr

2、on diffusionpnhole driftelectron driftChargeDensityDistancex+-ElectricalxFieldxPotentialVW2-W1(a) Current flow.(b) Charge density.(c) Electric field.(d) Electrostaticpotential.Digital Integrated CircuitsDevicesxpn0np0-W1W20pn(W2)n-regionp-regionLpdiffusionTypically avoided in Digital ICsDigital Inte

3、grated CircuitsDevicesxpn0np0-W1W20n-regionp-regiondiffusionThe Dominant Operation ModeDigital Integrated CircuitsDevicesDigital Integrated CircuitsDevicesVDID = IS(eVD/T 1)+VD+VDonID(a) Ideal diode model(b) First-order diode modelDigital Integrated CircuitsDevicesDigital Integrated CircuitsDevices2

4、5.015.05.05.0VD (V)0.1ID (A)0.100雪崩击穿雪崩击穿 Avalanche BreakdownDigital Integrated CircuitsDevicesIDRSCD+-VDDigital Integrated CircuitsDevicesVGS VTRonSDA Switch!|VGS|An MOS TransistorDigital Integrated CircuitsDevicesPolysiliconAluminumDigital Integrated CircuitsDevicesDSGGSDDSGNMOS三端器件三端器件BNMOS四端器件四端

5、器件PMOS三端器件三端器件PMOS四端器件四端器件Digital Integrated CircuitsDevicesn+n+p-substrateDSGBVGS+-DepletionRegionn-channelDigital Integrated CircuitsDevicesDigital Integrated CircuitsDevices-2.5-2-1.5-1-0.500.40.450.50.550.60.650.70.750.80.850.9VBS (V)VT (V)Digital Integrated CircuitsDevices平方关系VGS= 2.5 VVGS= 2.0

6、 VVGS= 1.5 VVGS= 1.0 V电阻区 饱和区VDS = VGS - VTVDSIDS00.511.522.50123456Digital Integrated CircuitsDevicesn+n+p-substrateDSGBVGSxLV(x)+VDSIDMOS transistor and its bias conditionsDigital Integrated CircuitsDevicesoxGSTHdq(x)= -C Wdxv-v(x)-V边界条件边界条件:V(x)|x=0=0, V(x)|x=L=VDSDigital Integrated CircuitsDevic

7、es三极管区三极管区(线性区线性区)每条曲线在每条曲线在VDSVGSVTH时时取最大值，且大小为：取最大值，且大小为：22noxDGSTHCWI=(V- V )LVDSVGSVTH时沟道刚好被夹断时沟道刚好被夹断W称为过驱动电压； 称为宽长比LGSTHV- VDigital Integrated CircuitsDevicesn+n+SGVGSDVDS VGS - VTVGS - VT+-Pinch-offDigital Integrated CircuitsDevicesIDnCoxWL(VGSVTH)VDS12VDS2IDnCox2WL(VGSVTH)2VDSVGSVTH (Pinchof

8、f)Qd(x)WCox(VGSV(x)VTH)当当V(x)接近接近VGS-VT，Qd(x)接近于接近于0，即反，即反型层将在型层将在XL处终止处终止，沟道被夹断。，沟道被夹断。Digital Integrated CircuitsDevicesDigital Integrated CircuitsDevicesLinearRelationship-4VDS (V)00.511.522.500.511.522.5x 10ID (A)VGS= 2.5 VVGS= 2.0 VVGS= 1.5 VVGS= 1.0 VEarly SaturationDigital Integrated Circuits

9、Devices (V/m)c = 1.5un (m/s)usat = 105Constant mobility (slope = )Constant velocityDigital Integrated CircuitsDevicesIDLong-channel deviceShort-channel deviceVDSVDSATVGS - VTVGS = VDDDigital Integrated CircuitsDevices00.511.522.50123456x 10-4VGS (V)ID (A)00.511.522.500.511.522.5x 10-4VGS (V)ID (A)qu

10、adraticquadraticlinearLong ChannelShort ChannelDigital Integrated CircuitsDevices-4VDS (V)00.511.522.500.511.522.5x 10ID (A)VGS= 2.5 VVGS= 2.0 VVGS= 1.5 VVGS= 1.0 V00.511.522.50123456x 10-4VDS (V)ID (A)VGS= 2.5 VVGS= 2.0 VVGS= 1.5 VVGS= 1.0 VResistive SaturationVDS = VGS - VTLong ChannelShort Channe

11、lDigital Integrated CircuitsDevicesSDGBDigital Integrated CircuitsDevices00.511.522.500.511.522.5x 10-4VDS (V)ID (A)VelocitySaturatedLinearSaturatedVDSAT=VGTVDS=VDSATVDS=VGTDigital Integrated CircuitsDevices-2.5-2-1.5-1-0.50-1-0.8-0.6-0.4-0.20 x 10-4VDS (V)ID (A)Assume all variablesnegative!VGS = -1

12、.0VVGS = -1.5VVGS = -2.0VVGS = -2.5VDigital Integrated CircuitsDevicesVGS VTRonSDIDVDSVGS = VDDVDD/2VDDR0RmidDigital Integrated CircuitsDevices0.511.522.501234567x 105VDD (V)Req (Ohm)Digital Integrated CircuitsDevicesDigital Integrated CircuitsDevicesDSGBCGDCGSCSBCDBCGBDigital Integrated CircuitsDevicesSDGCGCSDGCGCSDGCGCCut-offResistiveSaturation在数字电路设计时最重要的工作区: 饱和区、截至区Digital Integrated CircuitsDevicesWLCoxWLCox22WLCox3CGCCGCSVDS/(VGS-VT)CGCD01CGCCGCS = CGCDCGCBWLCoxWLCox2VGSCGC和和 VGS的关系的关系(with VDS = 0)CGC与与饱和程度的关系饱和程度的关系Digital Inte