EMT 251 SPICE NETLIST

Introduction SPICE (Simulation with Integrated Circuits Emphasis) SPICE (Simulation with Integrated Circuits Emphasis) General purpose circuit simulator which widely used in microelectronics industry General purpose circuit simulator which widely used in microelectronics industry Developed at University of California Berkeley Developed at University of California Berkeley Many variants e.g. HSPICE, PSPICE etc. Many variants e.g. HSPICE, PSPICE etc. Uses a simple netlist format for data input Uses a simple netlist format for data input Most manufacturers provide SPICE models as an essential for CAD tool Most manufacturers provide SPICE models as an essential for CAD tool Knowledge of various device parameters are essential for performing detailed circuit simulations and for optimizing design Knowledge of various device parameters are essential for performing detailed circuit simulations and for optimizing design

Cont… SPICE had three built-in MOSFET models: SPICE had three built-in MOSFET models: Level 1 (MOS1) >> described by square-law current- voltage characteristics Level 1 (MOS1) >> described by square-law current- voltage characteristics Level 2 (MOS2) >> detailed analytical MOSFET model Level 2 (MOS2) >> detailed analytical MOSFET model Level 3 (MOS3) >> semi-empirical model Level 3 (MOS3) >> semi-empirical model Recently, BSIM3 (Berkeley Short-Channel IGFET Model) ver. has been added to allow more accurate characterization of sub-micron MOSFET characteristics Recently, BSIM3 (Berkeley Short-Channel IGFET Model) ver. has been added to allow more accurate characterization of sub-micron MOSFET characteristics

SPICE Netlist Flow Chart

Advantages Improved memory utilisation Improved memory utilisation Improved convergence for numerical algorithms Improved convergence for numerical algorithms Improved accuracy Improved accuracy Improved execution speed Improved execution speed Can be used for mixed mode simulation Can be used for mixed mode simulation

Basic Concept Circuits for SPICE simulation are described: Circuits for SPICE simulation are described: The elements of the circuit (voltage, current, resistors, capacitors, transistors etc.) The elements of the circuit (voltage, current, resistors, capacitors, transistors etc.) A list of the nets/nodes (can be assigned names or numbers depending on the specific software used) A list of the nets/nodes (can be assigned names or numbers depending on the specific software used) Example: Example: circuit’s element list of nodes

Element Line Descriptions Voltage Source Voltage Source Vxx +node -node DC value Current Source Current Source Vxx +node -node DC value Resistor Resistor Rxx node1 node2 value Capacitor Capacitor Cxx node1 node2 value Diode Diode Dxx +node -node model_name plus other optional parameters Bipolar Transistor Bipolar Transistor Qxx collector base emitter model_name plus other optional parameters MOS Transistor MOS Transistor Mxx drain gate source bulk model_name plus other optional parameters Note: parameters in <> are optional and not required for simulation. Note: parameters in <> are optional and not required for simulation.

Analysis Descriptions SPICE can perform a variety of types of analysis on a circuit: SPICE can perform a variety of types of analysis on a circuit: Transient Analysis Transient Analysis.TRAN TSTEP TSTOP.TRAN TSTEP TSTOP TSTEP is the time step used between analysis points, and the smaller the value is, the more resolution you will get in your simulation. A typical value is 1nsec. TSTEP is the time step used between analysis points, and the smaller the value is, the more resolution you will get in your simulation. A typical value is 1nsec. TSTOP is the time when you want your transient analysis to stop. This value will depend on the frequency of your input signal(s) and the time it takes for your circuit to produce its final output. TSTOP is the time when you want your transient analysis to stop. This value will depend on the frequency of your input signal(s) and the time it takes for your circuit to produce its final output. TSTART is used if you want the analysis to start at some time other than Time=0. TSTART is used if you want the analysis to start at some time other than Time=0. TMAX is used to set the largest step time that will be used. This parameter is typically not needed. TMAX is used to set the largest step time that will be used. This parameter is typically not needed.

Cont.. DC Analysis DC Analysis Use a DC analysis if you want to view the response of the circuit when a source (voltage or current) sweeps between two DC values. The command and parameters are: Use a DC analysis if you want to view the response of the circuit when a source (voltage or current) sweeps between two DC values. The command and parameters are:.DC Source_name START STOP STEP Source_name is the name of the source that will be swept. Source_name is the name of the source that will be swept. START and STOP are the beginning and ending values of the sweep. START and STOP are the beginning and ending values of the sweep. STEP is the increment value used during the sweep. STEP is the increment value used during the sweep.

Cont.. AC Analysis AC Analysis To sweep all AC sources across a range of frequencies, use the.AC command. To sweep all AC sources across a range of frequencies, use the.AC command..AC Lin/Dec/Oct N FSTART FSTOP FSTART and FSTOP are the beginning and ending frequencies of the AC analysis. FSTART and FSTOP are the beginning and ending frequencies of the AC analysis. Select either Lin, Dec, or Oct for a linear, decade, or octave scaled sweep with N points analyzed. Select either Lin, Dec, or Oct for a linear, decade, or octave scaled sweep with N points analyzed.

SPICE Units The default units for SPICE are volts, amps, ohms, farads, henries, watts etc. You can specify values in decimal form, , or exponential form, 5.6e-3. SPICE also recognizes the following abbreviations: abbreviations: fE-15femto pE-12pico nE-9nano uE-6micro mE-3milli mE-3milli kE+3kilo megE+6mega gE+9giga tE+12tera For clarity you can add letters to the abbreviation as in 1U or 1UFARADS and both are read as the value 1e-6.. SPICE processes the first letter after the number and ignores the rest.

SPICE Netlist for inverter.global VDD GND.connect GND 0.lib /EDA/Mentor-training-ADK/technology/accusim/tsmc035.mod NOM.probe tran V.TRAN 0 400ns 1ns.subckt circuit portin portout MN1 DRAIN GET SOURCE BULK p L=0.4u W=1u MN2 DRAIN GET SOURCE BULK n L=0.4u W=1u.ends circuit.subckt inv in out MN1 out in VDD VDD p L=0.4u W=1u MN2 out in GND GND n L=0.4u W=1u.ends inv X13 portin portout circuit VOL1 VDD GND DC 5V VOL2 in GND PWL (0ns 0 100ns 0 101ns 5V 200ns 5V 201ns 0 300ns 0) X13 in out inv VOL1 VDD GND DC 5V VOL2 in GND PWL (0ns 0 100ns 0 101ns 5V 200ns 5V 201ns 0 300ns 0).end Format

Exercise (Write Netlist) 1.2.

Solution Answer 1: Answer 1:.global VDD GND.connect GND 0.lib /EDA/Mentor-training-ADK/technology/accusim/tsmc035.mod NOM.probe tran V.TRAN ns 1ns.subckt exercise1 A B OUT MP1 node1 A VDD VDD pmos L=0.4u W=1u MP2 OUT B node1 VDD pmos L=0.4u W=1u MN1 OUT A GND GND nmos L=0.4u W=1u MN2 OUT B GND GND nmos L=0.4u W=1u.ends inv X1 A B OUT exercise1 VOL1 VDD GND DC 5V VOL2 A GND PWL (0ns 0 100ns 0 101ns 5V 200ns 5V 201ns 0 300ns 0) VOL3 B GND PWL (0ns 0 100ns 0 101ns 5V 200ns 5V 201ns 0 300ns 0).end

Solution Question 2: Question 2:

Solution Answer 2: Answer 2:.global GND.connect GND 0.lib /EDA/Mentor-training-ADK/technology/accusim/tsmc035.mod NOM.probe tran V.TRAN ns 1ns V1 1 GND DC 5 R k R R3 3 GND 100meg C1 2 GND 100p V1 VDD GND DC 5V.plot DC v(2,3).end

POP QUIZ