深圳大學-數(shù)字集成電路(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介紹器件的基本公式介紹器件的基本公式q介紹用于手工分析的簡單模型介紹用于手工分析的簡單模型q介紹用于介紹用于SPICE模擬的器件模型模擬的器件模型q工藝偏差的影響工藝偏差的影響Digital Integrated CircuitsDevicesnppnBASiO2AlABAlAB 一維表示二極管符號IC工藝中PN結(jié)截面圖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雪崩擊穿雪崩擊穿 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平方關系VGS= 2.5 VVGS= 2.0

6、 VVGS= 1.5 VVGS= 1.0 V電阻區(qū) 飽和區(qū)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邊界條件邊界條件:V(x)|x=0=0, V(x)|x=L=VDSDigital Integrated CircuitsDevic

7、es三極管區(qū)三極管區(qū)(線性區(qū)線性區(qū))每條曲線在每條曲線在VDSVGSVTH時時取最大值，且大小為：取最大值，且大小為：22noxDGSTHCWI=(V- V )LVDSVGSVTH時溝道剛好被夾斷時溝道剛好被夾斷W稱為過驅(qū)動電壓； 稱為寬長比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)當當V(x)接近接近VGS-VT，Qd(x)接近于接近于0，即反，即反型層將在型層將在XL處終止處終止，溝道被夾斷。，溝道被夾斷。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在數(shù)字電路設計時最重要的工作區(qū): 飽和區(qū)、截至區(qū)Digital Integrated CircuitsDevicesWLCoxWLCox22WLCox3CGCCGCSVDS/(VGS-VT)CGCD01CGCCGCS = CGCDCGCBWLCoxWLCox2VGSCGC和和 VGS的關系的關系(with VDS = 0)CGC與與飽和程度的關系飽和程度的關系Digital Inte