Current revision is 2.12; revision history is at the
bottom of this page
SVCfilter™ is a program designed to expedite the
design and analysis of lowpass (and highpass) filters with
nearest 5% Standard-Value
Here are some pertinent features:
- SVCfilter is 32-bit Windows®
electrical filter design software nicely written to
help the radio amateur, technician or engineer design
and analyze lumped-element lowpass and highpass
- Order, topology and family are all
entered by clicking on buttons.
- If the Chebycheff or Cauer family is
chosen then three options for passband ripple
(.01, .044 and .200) are
- If the Cauer family is chosen then
four options for stopband depth (30, 40, 50 and 60 dB)
- Cutoff frequency is entered in the
usual text box and can be from audio through UHF.
- Cutoff frequency can be as low as
0.1 Hz, allowing the value of .159155 [
i.e., 1/(2*PI) ] to be used. This, in conjunction with
a termination value of one ohm, yields parts values for
the textbook classic "normalized" design.
- System impedance by default is 50
ohms but a textbox allows entry of any value of your
choice, for example 600 ohms for audio.
- Inductor Q values are set by default
to a value of one million. A textbox allows entry of
any value of your choice in the range of 10 minimum to
one million maximum.
- The graphic output draws the
schematic of the filter you have designed, and also
plots the responses of that filter (both transmission
and reflection). It selects the nearest 5% values for
the capacitors and shows those values as well as the
exact values and overlays the response plots for the
nearest values on top of the original exact-value
- Tuning buttons allow stepping the
cutoff frequency up or down in 1% steps and immediately
seeing the new performance of the redesigned filter on
- Place the cursor anywhere on the plot
and see the transmission, reflection, VSWR and envelope
delay values for that frequency.
- Inductors are retuned as necessary to
maintain the response of Cauer filters after nearest
capacitors are chosen.
- To maintain the high level of quality
of the graphic output, the outputs to the printer are
not "screen dumps" but instead are from a set of
dedicated routines which write directly to the printer.
The quality of the graphics as delivered by the printer
will be limited only by that printer, commonly several
hundred pixels per inch. The printer output on one
sheet contains the schematic with parts values along
with the set of responses.
- Click on the "Write Elsie File"
button to write a file to drive Elsie the filter design
and analysis program for followup filter examination in
even greater detail.
- Click on the "Write Spice schematic"
button to write a file to drive the LTspice simulator.
(Tonne Software has no connection with Linear
- This program was written to simplify
the sometimes difficult task of lumped-element lowpass
(and highpass) filter design by automating or setting
as default some of the more frequently-encountered
options. But it also includes analysis, uncommon for
such an application.
Updated to 2.12- fonts and buttons upgraded
Updated to 2.11- interface upgrades
Updated to 2.10- add Exit button to Display
Updated to 2.09- upgrade Design page appearance,
improve Spice schematic file writer
Updated to 2.08- lowered minimum bandwidth down to
.1 Hz so that "1/PI" can be used for the bandwidth. This
allows "normalized" (one ohm impedance level, one
radian/second bandwidth) values to be obtained.
Updated to 2.07- extensive Design page formatting
Updated to 1.06- improved plot capabilities
Updated to 1.05- extensive max/min value limits,
updates to error traps and screen headers
Updated to 1.04- add schematic with ideal parts
values to the top of the design page, Bessel family, time
display to cursor on plot
Updated to 1.03- add Cauer 30 dB stopband depth
option, tuning buttons, cursor-controlled data readout,
Bessel and Tonne families
Updated to 1.02- add hardcopy output and Elsie
Released as 1.01 1 August 2006