Parameters used: | sigma, BWp, G (optional: N ) |
Supports: | LP |
Pins used: | IN, OUT, GROUND |
N
sets the maximum number of RC cells, default 40
.
N
determines the upper limit of the frequency/phase.
sigma
smoothens or sharpens the phase response for a better match with the amplitude or the phase around BWp
; the default value of 0.5
is a compromise.
0dB
@fp
, set BWp=fp/100
and G=10⋅G
.
Parameters used: | BWp, BWs, G, Asc, N (optional: Rpar ) |
Supports: | AP, LP, HP |
Pins used: | IN, OUT, GROUND |
N
needs to be positive definite.
N
from 1
to 32
with Asc=3
will result in a difference error of 309.33mdB
between the lowest and the highest trace and ~12.5mdB
between two adjacent traces, @Asc
; the errors tend to be proportional with Asc
.
Asc
can only have two values:
Asc=0
⇒ 180o
constant phase delay for all orders with the following exceptions: N=2
with 167.103o
, N=3
with 178.862o
, N=4
with 179.95o
and N=5
with 179.999o
,Asc>0
⇒ N⋅90o
phase shift.
.AC
for higher orders, that's LTspice's engine doing its best to display very high values from a very simple circuit, .TRAN
is unaffected. Using the alternate solver or lowering Rpar
could help dampen the errors.
Parameters used: | fc, BWp, BWs, G, Asc, As, N (optional: sim, test, Rpar ) |
Supports: | AP, LP, HP, BP, BS |
Pins used: | IN, OUT, GROUND (optional: 0.1, 0.2, 0.3 ) |
Parameters used: | nT, fc, BWp, BWs, G, Asc, Ap, As, N (optional: sim, test, Rpar ) |
Supports: | AP, LP, HP, BP, BS |
Pins used: | IN, OUT, GROUND (optional: 0.1, 0.2, 0.3 ) |
Asc≤Ap
then frequency scaling will occur @Ap
(depending on the order and the value of nT
).
Parameters used: | fc, BWp, BWs, G, Asc, As, N (optional: sim, test, Rpar ) |
Supports: | LP, HP, BP, BS |
Pins used: | IN, OUT, GROUND (optional: 0.1, 0.2, 0.3, 0.4 ) |
Asc≥As
, As
will be considered.
Parameters used: | nT, fc, BWp, BWs, G, Asc, Ap, As, N (optional: sim, test, Rpar ) |
Supports: | LP, HP, BP, BS |
Pins used: | IN, OUT, GROUND (optional: 0.1, 0.2, 0.3, 0.4 ) |
N=0
, but can drop to ~2~3 or less if using extreme values for attenuations. E.g.: N=0
(32nd order), fc=0 BWp=1 BWs=1.1 Ap=0.001 As=260
⇒ a droop of about 0.2mdB
towards the end of the pass-band. The errors towards the other end (Ap>2.5, As<25
) are a bit greater, but still not grater than 0.1%
.
N=32
for the same conditions will show a real response but wrong, with many hundreds of dB
attenuation (and there may be other cases like this); it's because the elliptic nome q1
will get too small values for the matrix solver. Choosing the alternate solver may help a bit, but not much. In short, try to keep As<120
when N>0
, overly exaggerated values will not be without consequences.sim
) with a value much less than ωc
, e.g. for fc=0 BWp=1 BWs=2
⇒ the simulation time could be .TRAN 1m
⇒ sim=1m
(can be tested on the same schematic)