Digital Integrated Circuits© Prentice Hall 1995 Inverter THE INVERTERS

Digital Integrated Circuits© Prentice Hall 1995 Inverter DIGITAL GATES Fundamental Parameters l Functionality l Reliability, Robustness l Area l Performance »Speed (delay) »Power Consumption »Energy

Digital Integrated Circuits© Prentice Hall 1995 Inverter Noise in Digital Integrated Circuits

Digital Integrated Circuits© Prentice Hall 1995 Inverter DC Operation: Voltage Transfer Characteristic V(x) V(y) V OH V OL V LT V OH V OL f V(y)=V(x) Switching Logic Threshold Nominal Voltage Levels V(y)V(x) VIL VIH dVo/dVi =-1 NML NMH

Digital Integrated Circuits© Prentice Hall 1995 Inverter Mapping between analog and digital signals

Digital Integrated Circuits© Prentice Hall 1995 Inverter Definition of Noise Margins

Digital Integrated Circuits© Prentice Hall 1995 Inverter The Regenerative Property

Digital Integrated Circuits© Prentice Hall 1995 Inverter Fan-in and Fan-out

Digital Integrated Circuits© Prentice Hall 1995 Inverter The Ideal Gate

Digital Integrated Circuits© Prentice Hall 1995 Inverter VTC of Real Inverter

Digital Integrated Circuits© Prentice Hall 1995 Inverter Delay Definitions

Digital Integrated Circuits© Prentice Hall 1995 Inverter Ring Oscillator

Digital Integrated Circuits© Prentice Hall 1995 Inverter Power Dissipation

Digital Integrated Circuits© Prentice Hall 1995 Inverter CMOS INVERTER

Digital Integrated Circuits© Prentice Hall 1995 Inverter The CMOS Inverter: A First Glance As a designer, we can control: -Process (1.2um or 0.5um) -(W, L)p and (W, L)n -Power Supplies -Interconnection type -Fan-in/Fan-out

Digital Integrated Circuits© Prentice Hall 1995 Inverter CMOS Inverters Polysilicon In Out V DD GND PMOS NMOS SMOS 2  um or 0.7um Metal 1 Bulk Contacts Nwell Diffusion (N+) Diffusion (P+)

Digital Integrated Circuits© Prentice Hall 1995 Inverter Switch Model of CMOS Transistor

Digital Integrated Circuits© Prentice Hall 1995 Inverter CMOS Inverter: Steady State Response

Digital Integrated Circuits© Prentice Hall 1995 Inverter CMOS Inverter: Transient Response

Digital Integrated Circuits© Prentice Hall 1995 Inverter CMOS Properties l Full rail-to-rail swing l Symmetrical VTC l Propagation delay function of load capacitance and resistance of transistors l No static power dissipation l Direct path current during switching

Digital Integrated Circuits© Prentice Hall 1995 Inverter Voltage Transfer Characteristic

Digital Integrated Circuits© Prentice Hall 1995 Inverter CMOS Inverter Load Characteristics in = 1 V in = 2 V in = 3 V in = 4 V in = 4 V in = 5 V in = 2 V in = 3 Vout

Digital Integrated Circuits© Prentice Hall 1995 Inverter CMOS Inverter VTC Vin < Vtn -NMOS Off Vin > Vdd – Vtp -PMOS Off PMOS: linear if Vsg –Vtp > Vsd Vo > Vin +Vtp NMOS: Linear if Vgs-Vtn > Vds Vo < Vin –Vtn VOH: PMOS(lin) & NMOS(off) VOL: PMOS(off) & NMOS(lin) VIH: PMOS(sat) & NMOS(lin) VIL: PMOS(lin) & NMOS(sat) VLT: PMOS(sat) & NMOS(sat)

Digital Integrated Circuits© Prentice Hall 1995 Inverter CMOS Inverter VTC VOH: PMOS(lin) & NMOS(off) = Vdd VOL: PMOS(off) & NMOS(lin) = Gnd VIH: PMOS(sat) & NMOS(lin): Solve: VIL: PMOS(lin) & NMOS(sat): Solve:

Digital Integrated Circuits© Prentice Hall 1995 Inverter CMOS Inverter VTC VLT: PMOS(sat) & NMOS(sat): If Vtn = Vtp &  p =  n  VLT = Vdd/2: Gives a symmetric Inverter!

Digital Integrated Circuits© Prentice Hall 1995 Inverter Simulated VTC

Digital Integrated Circuits© Prentice Hall 1995 Inverter Gate Logic Switching Threshold  p // n V LT

Digital Integrated Circuits© Prentice Hall 1995 Inverter MOS Transistor Small Signal Model

Digital Integrated Circuits© Prentice Hall 1995 Inverter Determining V IH and V IL

Digital Integrated Circuits© Prentice Hall 1995 Inverter Propagation Delay

Digital Integrated Circuits© Prentice Hall 1995 Inverter CMOS Inverter: Transient Response

Digital Integrated Circuits© Prentice Hall 1995 Inverter CMOS Inverter Propagation Delay V DD V out V in = V DD C L I av t pHL = C L V swing /2 I av C L k n V DD ~

Digital Integrated Circuits© Prentice Hall 1995 Inverter CMOS Inverter Propagation Delay V DD V out V in = V DD C L Vdd Vo Time VH Vdd-Vtn to t1 t2 VL NMOS(sat) NMOS(lin)

Digital Integrated Circuits© Prentice Hall 1995 Inverter CMOS Inverter Propagation Delay Similarly:

Digital Integrated Circuits© Prentice Hall 1995 Inverter CMOS Inverter Rise & Fall Time Similarly, Rise Time: Similarly, Fall Time:

Digital Integrated Circuits© Prentice Hall 1995 Inverter Computing the Capacitances

Digital Integrated Circuits© Prentice Hall 1995 Inverter CMOS Inverters Polysilicon In Out Metal1 V DD GND PMOS NMOS 1.2  m =2

Digital Integrated Circuits© Prentice Hall 1995 Inverter The Miller Effect

Digital Integrated Circuits© Prentice Hall 1995 Inverter Computing the Capacitances

Digital Integrated Circuits© Prentice Hall 1995 Inverter Impact of Rise Time on Delay

Digital Integrated Circuits© Prentice Hall 1995 Inverter Delay as a function of V DD

Digital Integrated Circuits© Prentice Hall 1995 Inverter Where Does Power Go in CMOS?

Digital Integrated Circuits© Prentice Hall 1995 Inverter Dynamic Power Dissipation Energy/transition = C L * V dd 2 Power = Energy/transition *f =C L * V dd 2 * f Need to reduce C L, V dd, andf to reduce power. VinVout C L Vdd Not a function of transistor sizes!

Digital Integrated Circuits© Prentice Hall 1995 Inverter Impact of Technology Scaling

Digital Integrated Circuits© Prentice Hall 1995 Inverter Technology Evolution

Digital Integrated Circuits© Prentice Hall 1995 Inverter Technology Scaling (1) Minimum Feature Size

Digital Integrated Circuits© Prentice Hall 1995 Inverter Technology Scaling (2) Number of components per chip

Digital Integrated Circuits© Prentice Hall 1995 Inverter Propagation Delay Scaling

Digital Integrated Circuits© Prentice Hall 1995 Inverter Technology Scaling Models

Digital Integrated Circuits© Prentice Hall 1995 Inverter Scaling Relationships for Long Channel Devices

Digital Integrated Circuits© Prentice Hall 1995 Inverter Scaling of Short Channel Devices