LAPLACE

Currently ngspice does not offer a direct E-Source element with the LAPLACE option. There is however a XSPICE code model equivalent called s_xfer (see Chapt. 12.2.16), which you may invoke manually. The XSPICE option has to be enabled (32.1). AC (15.3.1) and transient analysis (15.3.9) is supported.

The following E-Source:

ELOPASS 4 0 LAPLACE {V(1)} + {5 * (s/100 + 1) / (s^2/42000 + s/60 + 1)}

may be replaced by:

AELOPASS 1 int_4 filter1 .model filter1 s_xfer(gain=5 + num_coeff=[{1/100} 1] + den_coeff=[{1/42000} {1/60} 1] + int_ic=[0 0]) ELOPASS 4 0 int_4 0 1

where you have the voltage of node 1 as input, an intermediate output node int_4 and an E-source as buffer to keep the name `ELOPASS' available if further processing is required.

If the controlling expression is more complex than just a voltage node, you may add a B-Source (5.1) for evaluating the expression before entering the A-device.

E-Source with complex controlling expression:

ELOPASS 4 0 LAPLACE {V(1)*v(2)} {10 / (s/6800 + 1)}

may be replaced by:

BELOPASS int_1 0 V=V(1)*v(2) AELOPASS int_1 int_4 filter1 .model filter1 s_xfer(gain=10 + num_coeff=[1] + den_coeff=[{1/6800} 1] + int_ic=[0]) ELOPASS 4 0 int_4 0 1