Switch Capacitor Filter Simulation

SC : Switch Capacitor Filter Simulation

Requires: Gateway, SmartSpiceRF & SmartView

Minimum required Versions: Gateway 2.12.10.R, SmartSpiceRF 1.6.5.R

Loading the Example Circuit

To load the switched-capacitor example circuit, select File->Open->Schematic. When the file browser appears, navigate to the directory where the SILVACO RF Demo PDK kit was installed, and descend to .\gateway\examples\sc directory. In this directory, select the file SC_test.schlr. The switched-capacitor filter testbench schematic will then appear. The lower hierarchical views of the SC_test block are shown in schematic 1 and schematic 2 respectively.

Generating Netlists.

Netlists are ASCII files used to describe circuits. Gateway can create two different netlist formats: SmartSpice or Guardian. See the Gateway user manual for more information on these formats.

To generate a netlist for circuit simulation, either select SimulationView->SmartSpice Netlist or click on the SmartSpice Netlist button. The SmartSpice netlist will then appear.

Switched-Capacitor Filter Circuit Simulation

SmartSpiceRF needs more than just a netlist to simulate. To perform a meaningful simulation the simulator needs models, a netlist and stimulus. All of the information comes together in the form of an input deck, or a *.in file, which ultimately provides the input to SmartSpiceRF.

This section presents the switched-capacitor filter simulations performed with SmartSpiceRF. Various types of simulations are presented here using two different test benches. Transient analysis is performed using SC_test.schlr. Transfer function and output noise are performed using SC_test_PSS.schlr.

Switched-Capacitor Filter

Click on the simulation toolbar button Edit Control File. The control file SC_test.ctr provides a path to the SILVACO RF Demo PDK models as well as SmartSpiceRF .dot statements. The control file combines with the netlist to create an input deck for SmartSpiceRF.

Edit Control File

In our control file, you can see the library paths and the analysis type specified.

Transient Analysis

Transient analysis statement is shown as follows:

*******************************************

.TRAN 0.1n 20u

*******************************************

Click on "Run" button to begin the simulation in Gateway. After the simulation is finished, the simulation results appear in the SmartView window. Then, select vector v(out) from tran1 and click Plot . This produces the tranisent simulation plot .

Transfer Function and Output Noise.

To perform transfer function and output noise, load the schematic called SC_test_PSS.schlr. Click on the "Generate Netlist" button to generate the netlist. Open the control file, SC_test_PSS.ctr, to view the analysis statements.

Click on the "Run" button to begin the simulation in Gateway. After the simulation is finished, the simulation results appear in the SmartView window. Then, select vector v(out) from hac1 and click Plot. The transfer function is shown in the SmartView Window. pngview

To display the output noise, choose vector onoise_s from hnoise1 and click Plot. Output noise is shown in the SmartView Window pngview.