Cadence Tutorial - IC Design

Once we have created the schematic and symbol, we will want to test the circuit. While designing the standard cells we used HSPICE to do the simulation.

1. We will want to create a new cell view to test the standard cell in, since we will need to hook up voltage sources and capacitors to test it. Thus we again go to library manager and select create new cell view. Here we show the new Cell view as being named tutorial_and2_lp_4x_test

2. Now we will need to insert the standard cell we're going to simulate as well as other components. Insert the AND gate we have used in the schematic and symbol tutorials, using the insert components button.

4. Now we will need to add other analog components. To test the circuit, we'll need a voltage supply (vdc) ,ground (gnd) , 2 pulsing voltage supplies (vpulse), to simulate the inputs and a capacitor (cap) to simulate the load.

5. Now the schematic should look something like this.

6. Again like in the schematic tutorial, connect the devices correctly using the wire button. Then we can select the properties button to define the values of the Voltage supply , capacitor etc. The voltage supply is shown below.

7. Set the pulsed voltage supply as shown below. We have found it useful to double the width of the pulse for each additional supply, for example if a standard cell has 3 inputs, the widths would be 10 ns , 20 ns, 40 ns. This way all possible input combiations will be covered.

8. Now we should have defined all the variables in our test schematic. We will now use the Analog Artist menu to simulate our standard cell. To start Analog Artist, from the test schematic view, go Tools >> Analog Artist.

9. From the Analog Artist menu, we must first select the simulator we want use, in our case we will use HSPICE. Go to setup >> Simulator/Directlry/Host... then select HSPICE from the list.

10. After selecting the Simulator, we need to chose what type of analysis you want to perform. Go to Analyses >> Choose Transient Analysis

11. Now we are ready to simulate. This is how the Analog artist window should look like before you get ready to simulate. Hit the green light to start the simulation.

12. Once the simulation has run, you will want to look at the voltage of the output and intup. To do this select Results >> Direct Plot >> transient results. You will need to select which wires you want to have displayed on the plot. Just click on the wire and it will be come dashed.

13. Once the wires have been select, hit Esc and the graph will pop up. Using the A and B buttons on the left, you can measure the rise and fall times. You can also use "z" to zoom into the graph to get an accurate position, use "f" to return the full view. In this example we see the fall time from 2.7 V to .3 V is 2.49 ns. We also see that the gate does in fact perform the logic of an AND gate.