DOST-ASTI Electric Manual

Electric VLSI Design System Training Manual (Version 6.03)

Advanced Science and Technology Institute Department of Science and Technology

ASTI-VCTI OpenLab Training Series Introduction to Full-Custom Digital IC Design Flow


Loading Electric Load Electric by either clicking the Electric icon on the desktop or by clicking on Start Programs Electric. The Electric Display Shown below is a typical Electric display with some of its essential features. Components Menu

Pulldown Menu

Editing Window

Messages Window

Status Area

The editing window or design window is the largest window that initially says “No facet in this window” (this indicates that no circuit is being displayed in that window). The messages window is a text window that is typically found at the bottom of the screen. This is used for all textual communication. The pulldown menu contains a list of command options. The components menu shows a list of nodes or components (in black outline) and arcs or wires (in red outline) that can be used in the design. The selected arc is highlighted with a bolder red outline. The status area provides useful information about the design state.

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SCHEMATIC Setting the Schematic Technology 1. Click on Technology Change Current Technology… from the pulldown menu. 2. Select schematic, analog as the technology (you will have to scroll down to find it). 3. Click OK. Notice that the symbols in the components menu will change to a schematic set. 4. Click on the 4 – Port box in the components menu. This will convert all the transistors in the components menu to 4-port transistors. Changing the Lambda Size 1. Click on Technology Change Units…. 2. Change Lambda Size to 2000. 3. Change Display Units to Microns. 4. Change Internal Units to Half-Millimicrons. 5. Click OK. Creating a New Library 1. Click on File New Library… on the pulldown menu. 2. Type the library name that you want to create. 3. Click OK. 4. To save the new library, click on File Save Library… on the pulldown menu. 5. On the Library File Creation window, browse through the file folders and select the folder where you want to save the library. 6. Click OK. A message confirming that the new library has been saved will be displayed in the message window. Creating a New Schematic Facet 1. Click on Facets Edit Facet. 2. Select the appropriate library. 3. Click New Facet. 4. Type the facet name that you want to create. Set the facet view to schematic. 5. Click OK. Adding Components 1. Select the desired device in the components menu by using the left mouse button. A white outline will appear around the chosen component. 2. Click on the design window to drop the component. Selecting Components and Ports 1. To select a component, left click on the node or component in the design window. A box that highlights the component appears, which indicates that it has been selected. In the second and third figure on the right, DC voltage sources are shown with highlights indicating that t hese components were selected. 2. Ports are the connection sites on nodes where the wires connect. A single node could have several ports. To select a port, click inside the figure of the node near the location of the desired port. The second and third figures on the right are voltage sources with the positive and negative terminals selected, respectively.

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Changing Components Properties 1. Highlight the device property label by clicking it. A white X mark should appear on this label. 2. Double click the property label to access the device Information window. 3. Modify the properties that you want to change. 4. Click OK. For the voltage sources in the previous page, the device property label is DC. Adding Export Pins 1. Select the node in the components menu. 2. Click on the design window to drop the export pin. 3. Type the export name and indicate the appropriate export characteristic. Table 1 lists the most commonly used export pins and their corresponding export characteristics. 4. Click OK.

Table 1

Export Pin Vdd Gnd Input Output

Export Characteristic Power Ground Input Output

Adding Wires 1. In the components menu, check if the wire arc (blue line) is highlighted (with a bold red outline). If it is not highlighted, click on the wire arc to select it. 2. Select the wire starting point by left clicking the component near the desired port. Make sure that the desired port is highlighted, as discussed in Selecting Components and Ports, before proceeding to the next step. 3. To create the wire, right click on another device port (to connect two device ports) or anywhere on the design window (to create a wire segment). Once a wire has been created, the other end is highlighted. Adding Voltage/Current Sources 1. In the components menu, click the Spice node to access the Spice list. 2. Choose Voltage/Current Source from the Spice list. 3. Click on the design window to drop the voltage/current source. 4. Type the appropriate SPICE card parameters in the SPICE Card window. Table 2 is a list of SPICE card formats for the different types of sources. 5. Click OK. Adding Voltage/Current Meters 1. In the components menu, click the Spice node to access the Spice list. 2. Choose Voltage/Current Meter from the Spice list. 3. Click on the design window to drop the voltage/current meter. 4. To plot the voltage across a device, connect the voltage meter in parallel to that device. To plot the current through a device connect the current meter in series to that device. Choosing the Circuit Analysis 1. In the components menu, click the Spice node to access the Spice list. 2. Three options (transient, DC and AC) are available for the circuit analysis. Choose the appropriate analysis from the Spice list. 3. Click on the design window to drop the chosen analysis.

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4. Type the appropriate SPICE card parameters in the SPICE Card window. Table 3 is a list of SPICE card formats for the different analyses. 5. Click OK.

Table 2

Source Type DC

Syntax DC Value

Parameters

Pulse

PULSE(V1 V2 TD Tr Tf PW Pd)

Piecewise linear (PWL)

PWL(T1 V1 T2 V2 T3 V3…)

Sinusoid

SIN(VO VA FREQ TD THETA PHASE)

Value – the value of the source V1 – initial value V2 – peak value TD – initial delay time Tr – rise time Tf – fall time PW – pulse width Pd – period (Ti Vi) – the value Vi of the source at time Ti VO – offset value VA – amplitude FREQ – frequency in Hz TD – delay in seconds THETA – damping factor per second PHASE – phase in degrees

Table 3

Analysis

Syntax

Parameters

Transient

TSTEP TSTOP

DC

START STOP STEP

AC With linear frequency variation

LIN NP FSTART FSTOP

With decade variation

DEC ND FSTART FSTOP

With octave variation

OCT NO FSTART FSTOP

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TSTEP – printing increment TSTOP – final time TSTART – starting time (if omitted, TSTART is assumed to be zero) TMAX – maximum step size UIC (Use Initial Condition) instructs SPICE to use the specified initial condition instead of the quiescent operating point before beginning the transient analysis. START – starting value STOP – ending value STEP – size of the increment NP – number of points FSTART – start frequency in Hz FSTOP – stop frequency in Hz ND – number of frequency points per decade FSTART – start frequency in Hz FSTOP – stop frequency in Hz NO - number of frequency points per octave FSTART – start frequency in Hz FSTOP – stop frequency in Hz



Saving the Schematic To save the schematic design that you created, click on File Save All Libraries from the pulldown menu. (Using the shortcut control key Ctrl-S will also save the circuit.) A message confirming that all facets of the library has been saved will be displayed in the message window. Creating an Icon for the Schematic 1. To create the icon facet of a schematic, open first its schematic facet. An icon is a symbol facet associated to the schematic facet. Make sure that you have created all the relevant exports before creating the icon. Table 4 2. To configure the appearance of the icon, click on View Icon Options…. Inputs on Left side a. Make sure that the options have Outputs on Right side the settings as listed in Table 4. Bidir. on Top side b. Check the Draw leads option. Power on Top side c. Check the Draw body option. Ground on Bottom side d. Click OK. Clock on Left side 3. Click on View Make Icon from the Export location Lead end pulldown menu to create the icon facet. Export style Outward A new design window will appear Export technology Schematic containing the icon. 4. Edit the icon facet if you want to make further changes on its appearance. Creating a Schematic SPICE Netlist 1. Click on Tools Simulation Interface SPICE Options…. a. Set the File format to SPICE3 and the SPICE level to 3. b. Check the Use Node Names option. c. Click on Use Header Cards From File. In the SPICE Model File Selection window set the file type to All Files (*.*). d. Browse through the folder list to locate the model file (\\Electric\models\BSIM3v31.txt). Select the model file. e. Click OK. 2. Before creating the SPICE netlist, make sure that all connections are checked. Refer to Checking for Connectivity on the Tips section of this manual. 3. Click on Tools Simulation Interface Write SPICE Deck from the pulldown menu to create a SPICE netlist of your schematic design. 4. Add a .cir extension to the file name. 5. Click Save.

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LAYOUT Setting the Layout Technology 1. Click on Technology Change Current Technology… from the pulldown menu. 2. Select mocmossub as the technology (you will have to scroll down to find it). 3. Click OK. The symbols in the schematic menu will change to a mocmos subset. Changing the Lambda Size 1. Click on Technology Change Units. 2. Change Lambda Size to 350. 3. Change Display Units to Microns. 4. Change Internal Units to Half-Millimicrons. 5. Click OK. Creating a New Layout Facet 1. Click on Facets Edit Facet. 2. Select the appropriate library. 3. Click New Facet. 4. Type the facet name that you want to create. Set the facet view to layout. 5. Click OK. Adding Nodes 1. Select a node from the components menu by using the left mouse button. 2. Click on the design window. Note: Nodes

in the mocmossub components menu are the ones in blue outlines.

Adding Arcs 1. Select an arc in the components menu. 2. Choose the arc starting point by left clicking the node near the desired port. Make sure that the desired port is highlighted before proceeding to the next step. 3. To create the arc, right click on another node port (to connect two node ports) or anywhere on the design window (to create an arc segment). Once an arc has been created, the other end is highlighted. Note: Arcs

in the mocmossub components menu are the ones in red outlines.

Adding Export Pins 1. Select the node or arc to be exported. 2. Click on Export Create Export…. 3. Type the export name and indicate the appropriate export characteristic. Checking the Layout for Design Rule Errors Before proceeding to the simulation, check for any layout violations by running a Design Rule Check (DRC). Design rules are the set of rules that must be followed when a given design is laid out. To run a DRC, click on Tools DRC Hierarchical Check. Saving the Layout To save the layout that you created click on File Save All Libraries from the pulldown menu. (Using the shortcut control key Ctrl-S will also save the layout.) A message confirming that all facets of the library has been saved will be displayed in the message window.

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Creating a SPICE Netlist Using the Layout Instance 1. Create a new schematic facet by following the instructions in the Schematic section of this manual. 2. Click on Edit New Facet Instance…. Click the name of the layout that you want to instantiate. 3. Click OK and click on the design window. An instance box of the circuit layout now appears on the design window. 4. Click on Export Re-Export Everything. 5. Add necessary components for simulation such as voltage/current sources, ground, voltage/current meters and load capacitances. 6. Save the circuit. 7. Change the current technology to mocmossub. Notice that the symbols in the components menu will change from a schematic set to a layout set. 8. Click on Tools Simulation Interface SPICE Options…. a. Set the File format to SPICE3 and the SPICE level to 3. b. Check the Use Node Names option. c. Check the Use Parasitics option. d. Click on Use Header Cards From File. In the SPICE Model File Selection window set the file type to All Files (*.*). e. Browse through the folder list to locate the model file (\\Electric\models\BSIM3v31.txt). Select the model file. f. Click OK. 9. Before creating the SPICE netlist, make sure that all connections are checked. Refer to Transistor Layout on the Tips section of this manual. 10. Click on Tools Simulation Interface Write SPICE Deck from the pulldown menu to create a SPICE netlist of your circuit design. 11. Add a .cir extension to the file name. 12. Click Save. Determining the Area of the Layout 1. Click on Info Measure Distance from the pulldown menu. 2. Press X on the keyboard. This key tells Electric that you are ready to specify the starting point of your measurement. 3. Left click on the starting point of your measurement. 4. Left click on the end point of your measurement. A line appears and the value of the length is shown. 5. Press the Enter key when done.

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SIMULATION Simulating the Circuit Behavior Using WinSpice 1. Run WinSpice by clicking on Start Programs WinSpice. 2. Open the *.cir file in WinSpice. 3. Wait until WinSpice starts displaying the simulation data. Press Esc to skip the viewing of data points. WinSpice will automatically plot in a single window all voltages and currents that were specified in the schematic. Plotting Waveforms in Separate Windows There are 2 ways to plot the parameters in separate windows. Through the cir file: 1. Open the *.cir file using Notepad or any other text editor program. 2. Add the following line for each parameter to be plotted in a separate window: .PRINT

3. Run the simulation in WinSpice. Example: Plotting several parameters in one window,

.PRINT TRAN V(Va) V(Vb) V(Vout)

The above picture shows the transient response of Va, Vb and Vout superimposed in one plot. To plot each parameter in separate windows, delete the above code and rewrite it as: .PRINT TRAN V(Va) .PRINT TRAN V(Vb) .PRINT TRAN V(Vout)

Through the WinSpice command prompt: If the simulation has been run already, simply type the following on the WinSpice command prompt: plot Example:

Winspice 1 -> plot v(va) Winspice 2 -> plot v(vb) Winspice 3 -> plot v(vout)

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SHORTCUT CONTROL KEYS

Open Library Save All Libraries Quit Cut Copy Paste Duplicate Undo Redo Rotate 90 Degrees Counterclockwise Select All Edit Facet Down Hierarchy Up Hierarchy Look Inside Highlighted Create Export Fill Window Zoom Out Zoom In Fit to Screen Focus on Highlighted Left Right Up Down Toggle Grid Delete Window Get Info

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Ctrl-O Ctrl-S Ctrl-Q Ctrl-X Ctrl-C Ctrl-V Ctrl-M Ctrl-Z Ctrl-R Ctrl-J Ctrl-A Ctrl-N Ctrl-D Ctrl-U Ctrl-P Ctrl-E Ctrl-9 Ctrl-0 Ctrl-7 Ctrl-9 Ctrl-F Ctrl-4 Ctrl-6 Ctrl-8 Ctrl-2 Ctrl-G Ctrl-W Ctrl-I



ELECTRIC AND WINSPICE ERROR / WARNING MESSAGES Listed here are some of the most common errors encountered and their corresponding solutions. Electric Warning Messages Warning: there may be inconsistent ground networks in Warning: there may be inconsistent power networks in Warning: top of source [nodex]/DC 3.3 in facet not connected to an export

This means that the ground and power in the circuit is not connected to the DC source. Refer to Checking forCconnectivity in the Tips section of this manual. WinSpice Error Messages Illegal Characters in the SPICE Netlist Error in ‘x.cir’ on line x : _nodex xxx x => unknown device type - error

To remove this type of error, follow these steps. 1. Open the *.cir file using Notepad or any other text editor program. 2. Scroll down and look for the illegal character ‘ ’. Substitute all occurrences of this character with the letter ‘v’. 3. Save the text file. Example: ** Sources and special nodes: node11 Vout_1 Vout DC 0 Vnode9 Vout_1 0 sin(1.65 1m 1k 0 0 0) Inode6 VDD Ibias DC 100u Vnode2 VDD 0 DC 3.3 .PRINT TRAN I( node11) V(Vout_1) .TRAN 10u 10m 10u .END

Corrected Example: Notice that all occurrences of ‘ ’ are now substituted with ‘v’. ** Sources and special nodes: vnode11 Vout_1 Vout DC 0 Vnode9 Vout_1 0 sin(1.65 1m 1k 0 0 0) Inode6 VDD Ibias DC 100u Vnode2 VDD 0 DC 3.3 .PRINT TRAN I( vnode11) V(Vout_1) .TRAN 10u 10m 10u .END Note:

Text characters in a SPICE netlist are not case-sensitive.

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Unconnected Nodes Error in ‘x.cir’ on line x : mnodex Vout Vin 0 * N L=0.35U W=0.80U Error in ‘x.cir’ on line x : mnodex Vdd Vin Vout * P L=0.35U W=3.20U Only level 9 B3S0I can have 5 nodes Note: * in

the beginning of a line denotes it is a comment in the program and is therefore not an error, while an within a command denotes a missing node in the program

*

To remove this type of error, follow these steps. 1. Open the *.cir file using Notepad or any other text editor program. 2. Scroll down and look for the line mentioned in the error message. Example:

Mnode5 Vout Vin 0 * N L=0.35U W=0.80U Mnode6 Vdd Vin Vout * P L=0.35U W=3.20U

3. Check the schematic for unconnected nodes in the transistors. For this example, the bulk nodes are unconnected. Connect the bulk correspondingly (to ground for NMOS and to Vdd for PMOS). 4. Save the schematic and recreate the SPICE netlist. Check if the line is correctly modified by opening the *.cir file again. Corrected Example: Mnode5 Vout Vin 0 0 N L=0.35U W=0.80U Mnode6 Vdd Vin Vout Vdd P L=0.35U W=3.20U

Missing Model Files Unable to find definition of model 1 – default assumed Error: no unlabeled parameter permitted on mosfet Error: unresolved model or device references: -p n

To remove this type of error, follow these steps. 1. Open the *.cir file using Notepad or any other text editor program. 2. Check if the model files for NMOS and PMOS are at the top most part of the file. Example:

.model P PMOS +… +… .model N NMOS +… +…

3. If the model files are not found, go to the schematic window. 4. Check the spice options by clicking on Tools -> Simulation Interface -> SPICE Options. 5. Make sure that all the settings are as specified in the Schematic section of this manual. 6. Re-create the SPICE netlist by clicking on Tools -> Simulation Interface -> Write SPICE Deck. 7. The model file should already be included in the *.cir file.

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TIPS Checking for Connectivity Click on a component. All connections to the component should appear highlighted. Example:

Notice that all the nodes connected to ground are highlighted. An example of an unconnected wire is shown below:

The ground in black circle is not connected to the rest of the nodes connected to ground. If this is the case, do the following: 1. Save the library (Ctrl-S). 2. Open the same library without closing the current facet. 3. Check for connectivity. The nodes concerned should now all be highlighted.

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Transistor Layout 1. Overlapping two nodes does not automatically connect them. This will only generate spacing errors. Make sure to connect them first using an arc and then move them closer as in the example below:

a. Unconnected

b. Connected

c. Compress further

2. Try to move the node closer one step at a time while checking the message window to see if a DRC error is generated. Or you can perform the DRC independently as specified in the Layout section of this manual. 3. Checking their connectivity is the same as with the schematic. Clicking a node should highlight all that is connected to it as in the figures below.

Connected

Unconnected

All nodes connected are highlighted 4. If nodes are well connected, and there are still spacing errors, double click on the arc connecting the nodes with the spacing error.

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5. Uncheck “ends extend” (This option sizes the node / arc in proportion to the node width). 6. Another cause of spacing errors is multiple components that are overlapping. One can easily identify this by moving the component concerned and checking if there is an extra component under it as in the example below.

Two coinciding nodes

Extra component under the node

In this case, the extra component is not connected to the other nodes and so it generates the other spacing errors. Simply delete the extra component and run a DRC again. 7. If there is still a spacing error, then the two nodes must be really too close. One of the nodes should therefore be moved until the error disappears.

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DESIGN RULES FOR MOCMOSSUB TECHNOLOGY Arc widths (minimum sizes): metal1: 3 metal2: 3 metal3: 5 metal3: 3 metal4: 6 poly1: 2 poly2: 3 p/n active (active&select&well): active: 3, select extends by 2, well extends by 6 active: 3 Pin/Node sizes (minimum sizes): metal1: 3 metal2: 3 metal3: 5 metal3: 3 metal4: 6 poly1: 2 poly2: 3 active: 3 select: 2 well: 12 Special nodes: p/n active-to-metal1 contact: cuts 2x2, separated 3 metal1 extends around cut by 1 (4x4) active extends around cut by 1.5 (5x5) select extends around active by 2 (8x8) well extends around active by 6 (17x17) poly1-to-metal1 contact: cuts 2x2, separated 3 metal1 extends around cut by 1 (4x4) poly1 extends around cut by 1.5 (5x5) poly2-to-metal1 contact: cuts 2x2 , separated 3 metal1 extends around cut by 1 (4x4) poly2 size: 3 (3x3) poly1-to-poly2 (capacitor) contact: cuts 2x2 [5.1], separated 3 poly2 size: 3 (3x3) poly1 extends around poly2 by 2 (7x7) Transistors: active is 3 wide and sticks out by 3 (3x8) poly1 is 2 wide and sticks out by 2 (7x2) transistor area is 3x2 select surrounds active by 2 (7x12) well surrounds active by 6 (15x20) Via1: cuts 2x2, separated 3

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metal1 extends around cut by 1 (4x4) metal2 extends around cut by 1 (4x4) Via2: cuts 2x2, separated 3 metal2 extends around cut by 1 (4x4) metal3 extends around cut by: 2 (6x6) (if 3-metal process) metal3 extends around cut by: 1 (4x4) (if 4-metal process) Via3: cuts 2x2, separated 4 metal3 extends around cut by: 1 (4x4) metal4 extends around cut by: 2 (6x6) Substrate/well contact: select extends around active by 2 well extends around active by 6 DRC: metal1-to-metal1: 3 metal2-to-metal2: 4 metal3-to-metal3: 3 metal4-to-metal4: 6 poly1-to-poly1: 3 poly1-to-active: 1 poly2-to-poly2: 3 poly2-to-active: 1 poly2-to-polyCut: 3 active-to-active: 3 select-to-trans: 3 polyCut/actCut-to-polyCut/actCut: 3 polyCut/actCut-to-via1: 2 polyCut-to-active: 2 actCut-to-poly: 2 via1-to-via1: 3 via1-to-via2: 2 via2-to-via2: 2 via3-to-via3: 4 Metals: Metal-1

Metal-2

Metal-3

Metal-4

Metal-5

Metal-6

2-metals: 3 wide 3 wide 3 apart 4 apart 1 over via1 1 over via1 3-metals: 3 wide 3 wide 5 wide 3 apart 3 apart 3 apart 1 over via1 1 over via1/2 2 over via2 4-metals: 3 wide 3 wide 3 wide 3 wide 3 apart 3 apart 3 apart 3 apart 1 over via1 1 over via1/2 1 over via2/3 1 over via3 5-metals: 3 wide 3 wide 3 wide 3 wide 4 wide 3 apart 3 apart 3 apart 3 apart 4 apart 1 over via1 1 over via1/2 1 over via2/3 1 over via3/4 1 over via4 6-metals: 3 wide 3 wide 3 wide 3 wide 3 wide 4 wide 3 apart 3 apart 3 apart 3 apart 3 apart 4 apart 1 over via1 1 over via1/2 1 over via2/3 1 over via3/4 1 over via4/5 1 over via5

Note: All

dimensions are given in lambda.

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DOST-ASTI Electric Manual

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