北大集成电路原理与设计之一：数字集成电路原理与设计课件04数字集成电路的基本单元电路-CMOS单

第四章CMOS单元电路4.1反相器直流特性GeneratedbyFoxitPDFCreator©FoxitSoftware反相器4.1CMOS反相器的直流特性4.2CMOS反相器的瞬态特性4.3CMOS反相器的设计GeneratedbyFoxitPDFCreator©FoxitSoftware特点：Vin作为PMOS和NMOS的共栅极；Vout作为共漏极；VDD作为PMOS的源极和体端；GND作为NMOS的源极和体端VVinout反相器的逻辑符号GeneratedbyFoxitPDFCreator©FoxitSoftware标准单元形式的门电路的版图设计通过等高的设计共享电源和地线通过邻接的设计减小面积GeneratedbyFoxitPDFCreator©FoxitSoftware反相器的直流特性Vin=0，NMOS截止，PMOS导通，稳态Vout=VDD,“1”；Vin=VDD，NMOS导通，PMOS截止,稳态Vout=0；Vin=VDDVDDVout=0Vout=VDDVin=0VDD反相器的工作特点：Vout=Vin；稳态单管导通，没有直通电流GeneratedbyFoxitPDFCreator©FoxitSoftware缩写对照：N-SP-OVinVout0VVTNDDVVDD+TPN-OP-LN-SP-LN-SP-SN-LP-SN-LP-ON-OP-SVout+VTP=VinVout+VTN=VinGeneratedbyFoxitPDFCreator©FoxitSoftware分析直流特性的出发点：直流条件下没有输出电流满足：IDN=IDPVoltageTransferCharacteristic(VTC)VinVout0VVTNDDVVDD+TPN-OP-LN-SP-LN-SP-SN-LP-SN-LP-ON-OP-SN-SP-OVDDVVinoutGeneratedbyFoxitPDFCreator©FoxitSoftware、反相器的VTC1、特点：N-O&P-L2、特点：N-S&P-LinTN0VV220,DPPinTPDDinTPoutDNoutDDOHDDIKVVVVVVIVVVVTNinoutTPVVVV2221222PinTPDDinTPoutNinTNoutinTPinTPDDrinTNNrPKVVVVVVKVVVVVVVVKVVKKK比例因子VDDVVinoutVout+VTP=VinVout+VTN=VinGeneratedbyFoxitPDFCreator©FoxitSoftware、特点：N-S&P-SoutTPinoutTNVVVVV22NinTNPinTPDDKVVKVVVTNrDDTPinrTNrDDTPrTNDDTPitrr1111=111VKVVVKVKVVKVVVVKK反相器的逻辑阈值电平（逻辑转折点）Vout+VTP=VinVout+VTN=VinGeneratedbyFoxitPDFCreator©FoxitSoftware、特点：N-L&P-S5、特点：N-L&P-OoutTNinDDTPVVVVV222NinTNinTNoutPinTPDDKVVVVVKVVV1222outinTNinTNinTPDDr1VVVVVVVVKDDinDDTPVVVV22NinTNinTNout0DPKVVVVVIout0VOL0VCMOS反相器实现全摆幅Vout+VTP=VinVout+VTN=VinGeneratedbyFoxitPDFCreator©FoxitSoftware的影响反相器比例因子对直流特性的影响：在VTN=-VTP前提下进行考虑，以便简化问题；TNrDDTPinrTNrDDTPrTNDDTPitrr1111=111VKVVVKVKVVKVVVVKKVDDVVinoutGeneratedbyFoxitPDFCreator©FoxitSoftware、PMOS阈值电压的影响；在Kr=1前提下进行考虑，以便简化问题TNrDDTPinrTNrDDTPrTNDDTPitrr1111=111VKVVVKVKVVKVVVVKKVDDVVinoutGeneratedbyFoxitPDFCreator©FoxitSoftware(VTC)VDDVVinoutVout+VTP=VinVout+VTN=VinGeneratedbyFoxitPDFCreator©FoxitSoftware的输入,输出不是一条垂直线VDDVVinoutGeneratedbyFoxitPDFCreator©FoxitSoftware=VTNIon=IDN=IDP=0，2.VTNVinVout-|VTP|Ion=IDN=IDPUP3.Vin=VitIon=IpeakatVin=Vit4.Vout+VTNVinVDD-|VTP|Ion=IDN=IDPDOWN5.VDD-|VTP|VinVDDIon=IDN=IDP=0，GeneratedbyFoxitPDFCreator©FoxitSoftware、反相器的直流噪声容限数字电路中信号在Vdd和Gnd之间转换，各种干扰信号，可能使得电路中某些结点的信号电平偏离理想电平（Vdd，Gnd），产生所谓的噪声噪声会对电路的可靠性造成影响i(t)InductivecouplingCapacitivecouplingPowerandgroundnoisev(t)VDDGeneratedbyFoxitPDFCreator©FoxitSoftware反相器噪声容限(NoiseMargins)噪声容限定义1：极限输出给定VOHmin和VOLmaxVOHminVoff(关门电平)VOLmaxVon(开门电平)VNL=Voff,VNH=VDD-Von电路的直流噪声容限——允许的输入电平变化范围，反映了电路的抗干扰能力GeneratedbyFoxitPDFCreator©FoxitSoftware噪声容限定义2：单位增益点在2、4区存在|dVout/dVin|=1的单位增益点在2、4区求得增益点对应的Vin(分别为Vc1和Vc2)，VNL=Vc1VNH=VDD-Vc21222outinTPinTPDDrinTNVVVVVVKVVGeneratedbyFoxitPDFCreator©FoxitSoftware：逻辑阈值点把Vit做为允许的输入高电平和低电平极限VNLM=VitVNHM=VDD-VitVNLM与VNHM中较小的决定最大直流噪声容限反相器的直流噪声容限TNrDDTPinrTNrDDTPrTNDDTPitrr1111=111VKVVVKVKVVKVVVVKKGeneratedbyFoxitPDFCreator©FoxitSoftware©FoxitSoftware©FoxitSoftware反相器4.1CMOS反相器的直流特性4.2CMOS反相器的瞬态特性4.3CMOS反相器的设计GeneratedbyFoxitPDFCreator©FoxitSoftware直流特性和瞬态特性直流特性有助于我们理解反相器中器件的工作状态和电路的噪声特性瞬态特性，即输入信号随着时间变化过程中，输出信号的变化情况瞬态特性决定着电路的速度VoutVin0.511.522.50.511.522.5NMOSresPMOSoffNMOSsatPMOSsatNMOSoffPMOSresNMOSsatPMOSresNMOSresPMOSsatVOLVOH0.9VOH0.1OHVtftrGeneratedbyFoxitPDFCreator©FoxitSoftware、上升时间和下降时间VOLVOH0.9VOH0.1OHVtftr(1)出现上升/下降的原因:Vin跳