LTC1264-7
12647fa
4
E
LECTR
IC
AL C CHARA TERIST
ICS
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: Input frequencies, f, are linearly phase shifted through the filter as
long as f ≤ f
C
; f
C
= cutoff frequency.
Figure 1 curve (A) shows the typical phase response of an LTC1264-7
operating at f
CLK
= 2.5MHz, f
C
= 100kHz. An endpoint straight line, curve
(B), depicts the ideal linear phase response of the filter. It is described by:
phase shift = 180° –
F
(f/f
C
); f ≤ f
C
.
F
is arbitrarily called the “phase factor” expressed in degrees. The phase
factor together with the specified deviation from the ideal straight line
allows the calculation of the phase at a given frequency. Note, the
maximum phase nonlinearity, Figure 1, occurs at the vicinity of f = 0.25 f
C
and = 0.75 f
C
. Example: The phase shift at 70kHz of the LTC1264-7 shown
in Figure 1 is: phase shift = 180° – 407° (70kHz/100kHz) ± nonlinearity =
–104.9° ± 1% or –104.9°± 1.05°.
Note 3: Group delay and group delay deviation are calculated from the
measured phase factor and phase deviation specifications.
Note 4: The filter cutoff frequency is abbreviated as f
CUTOFF
or f
C
.
Note 5: The AC swing is typically 9V
P-P
, 5.6V
P-P
, 1.8V
P-P
with ± 7.5V, ± 5V,
± 2.5V supply respectively. For more information refer to the THD + Noise
vs Input graphs.
Figure 1. Phase Response in the Passband (Note 2)
FREQUENCY (kHz)
0
–360
PHASE (DEG)
–270
–180
–90
0
90
180
20 40 60 80
LTC1264-7 F01
10010 30 50 70 90
A
B
f
CLK
= 2.5MHz
(f
CLK
/f
C
) = 25:1
