SVCfilter is one of the
programs included on the Bonus CD accompanying the ARRL
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
- 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) are available.
- Cutoff frequency is entered in
the usual text box and can be from audio through
- 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"
- 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 plot.
- Tuning buttons allow stepping the
cutoff frequency up or down in 1% steps and
immediately seeing the new performance of the
redesigned filter on the plot.
- 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
- 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 Technology
- 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
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
Updated to 1.06- improved plot
Updated to 1.05- extensive max/min value
limits, updates to error traps and screen
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