Figure 1 Lowpass filter
Figure 2 Smartspice Analysis - Voltage gain in dB as a function of frequency.
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Figure 1 Lowpass filter |
Figure 2 Smartspice Analysis - Voltage gain in dB as a function of frequency. |
The low pass filter circuit shown in figure 1 is described by the following spice input file.
LOW PASS FILTER * A subcircuit is use to model a nearly ideal opamp. .subckt opamp 1 2 3 * opamp input impedance is 100MEG Rin 1 2 100MEG * A voltage controlled voltage source models the opamp. * V+ in is node 1, V- in is node 2, and Output is node 3 * The gain is 1E8 EOPAMP 3 0 1 2 1E8 .ends X1 2 0 3 opamp R1 1 2 10K R2 2 3 10K C2 2 3 1.6n * We set up the input voltage source for both AC and * transient analysis. Vin 1 0 AC 1 pulse(0 5 0 0 0 1m 2m) .AC DEC 20 100 1MEG .probe .end