Lecture on PSpice

Introduction to SPICE  SPICE was originally developed at the University of California, Berkeley (1975).  Simulation Program for Integrated Circuits Emphasis  HSPICE = High-performance SPICE  PSpice = PC version of SPICE

SPICE Functions  DC analysis: DC transfer curve  Transient analysis: voltage and current as a function of time  AC Analysis: output as a function of frequency  Noise analysis  and more ….  SPICE has analog and digital libraries for standard components (Transistor, NAND, NOR, …)  Different temperatures Default temperature is 300K

Components  Independent voltage and current sources  Dependent voltage and current sources  Resistor  Capacitor  Inductor  Operational amplifier  Transistor  Digital gates …

SPICE Source File  Title statement: first line  Data statements: specify the Circuit, components, interconnections  Control statements: specify what types of analysis to perform on the circuit.  Output statements: specify outputs  Comment statements: begin with an asterisk (*)  End statement:.END  "+" sign (continuation sign)

Suffixes  TTera ( )  GGiga (10 +9 )  MEGMega (10 +6 )  KKilo (10 +3 )  MMili (10 -3 )  UMicro (10 -6 )  NNano (10 -9 )  PPico ( )  FFemto ( )

Independent DC Sources  Voltage source: Vname N+ N- Type Value  Current source: Iname N+ N- Type Value  Type: DC, AC or TRAN (transient) (like PULSE, …)  Vin 2 0 DC 10  Vin 2 0 AC 10  Is 3 4 DC 1.5  Voltage and Current Conventions N1(+) N2(-) N1(+) N2(-)

Dependent DC Sources  Voltage controlled voltage source: Ename N+ N- NC+ NC- Value  Voltage controlled current source: Gname N+ N- NC+ NC- Value  Current controlled voltage source: Hname N+ N- Vmeas Value  Current controlled current source: Fname N+ N- Vmeas Value  N+ and N- are terminals of the dependent source  NC+ and NC- are terminals of the controlling voltage source

Ename N+ N- NC+ NC- α Gname N+ N- NC+ NC- γ Hname N+ N- Vmeas ρ Fname N+ N- Vmeas β Vmeas N+ N- Vmeas

Example F1 0 3 Vmeas 0.5 Vmeas 4 0 DC 0

Resistors, Capacitors, Inductors  Rname N+ N- Value  Cname N+ N- Value  Lname N+ N- Value  IC = initial condition ( DC voltage or current ) Example: C pF 5V C pF L mH L mH 1mA 1pF _4_ V

Damped Sinusoidal Sources  Vname N+ N- SIN(VO VA FREQ TD THETA PHASE)  VO - offset voltage in volt.  VA - amplitude in volt.  f = FREQ in Hz  TD - delay in seconds  THETA - damping factor per second  Phase - phase in degrees  If TD, THETA and PHASE are not specified, it is assumed to be zero. Example: V1 1 2 SIN( ) V2 3 4 SIN( )

F=1, THETA=.4, VO=5, VA=3, TD=0, Phase=600

Piecewise linear source (PWL)  Vname N+ N- PWL(T 1 V 1 T 2 V 2 T 3 V 3...)  V i is the value source at time T i  Example: Vg 1 2 PWL(0 0 10U 5 100U 5 110U 0)

Pulse  Vname N+ N- PULSE(V1 V2 TD Tr Tf PW Period)  V1 - initial voltage  V2 - peak voltage  TD - initial delay time  Tr - rise time  Tf - fall time  pw- pulse-width  Period - period

Subcircuits  A subcircuit allows you to define a collection of elements as a subcircuit (e.g. an operational amplifier).SUBCKT SUBNAME N1 N2 N3... Element statements..ENDS SUBNAME  N1, N2, N3 are the external nodes of the subcircuit. The external nodes cannot be 0.  The node numbers used inside a subcircuit are strictly local, except for node 0 which is always global.

Example: µ741 (Op Amp) * Subcircuit for 741 op amp * +in (=1) -in (=2) out (=3).subckt opamp rin 1 2 2meg rout e k r meg c nf eout ends opamp741

Using Subcircuit vs 1 0 dc 5 r rf 2 3 1k x opamp741.dc vs option post.end

.OP Statement  Instructs SPICE to compute DC operating points voltage at each node current in each voltage source operating point for each element

.DC Statement  Increment (sweep) an independent source over a certain range with a specified step.DC SRCname START STOP STEP  SRCname = name of the source  START and STOP = starting and ending values  STEP = size of increments  Example:.DC V

.TRAN Statement  Specifies time interval for transient analysis.TRAN TSTEP TSTOP  TSTEP = increment  TSTOP = final time  TSTART = starting time

.AC Statement  Specify frequency (AC) analysis.AC LIN NPFSTART FSTOP  LIN = linear frequency variation  NP = number of points.  FSTART and FSTOP = start and stopping frequencies (Hz)  Example:.AC LIN

Output Statements .PLOT plots selected output variables, to design.lis using ASCII characters..PLOT is useful for looking at plotted results without access to AvanWaves. .PRINT DC V(2) prints node voltage value for node 2 in the design.lis file.

.PRINT &.PLOT .PRINT TYPEOV1 OV2 OV3... .PLOT TYPE OV1 OV2 OV3...  TYPE = type of analysis printed or plotted DC TRAN AC  OV1, OV2 = output variables Examples:.PLOT DC V(1,2) V(3) I(Vmeas).PRINT TRAN V(3,1) I(Vmeas)

Example 1

* We are interested in finding the following characteristics: * 1. Node voltages v12, v2 and current i4 when vin=10V * 2. Thevenin equivalent voltage and resistance, seen * at the output terminals v(3,0) VIN 1 0 DC 10 VMEAS 4 0 DC 0 *VMEAS is a 0V source to measure i4 F1 0 3 VMEAS 0.5 R K R K R K R K R K.tran.01n 50n.TF V(3,0) VIN.DC VIN PLOT DC V(1,2).END

Example 2

* pulse generator * +node -node V1 V2 TD TR TF PW PER VIN 1 0 PULSE ( N 0.1N 50N 100N) R M R M C uF * transient simulation for 50ns with 0.01ns step size.tran.1n 500n * dc simulation with stimulus voltage (source VIN) from 0 to 5V in 0.1V steps.DC VIN end

Example 3 * Thevenin Vs 1 0 DC 10V E R R R R R R R R TF V(5,6) Vs.plot DC V(5,6).plot DC I(Vs).DC Vs END V _ 5V

Example 4

OLD_HW1_Solution * Thevenin Vs 2 5 DC 100V Vmeas 2 3 DC 0V Fx 6 7 Vmeas 4.0 Ex R R R R R R MEG.TF V(4,0) Vs.plot DC V(5,4).plot DC V(1,0).plot DC I(Vmeas).DC Vs tran 1n 50n 0.END

Example

OLD_HW2_Solution Vs 1 0 AC 1 L m C n R M.AC LIN plot AC V(1,2) I(Vs).END