Datasheet
5Maxim Integrated
Digitally-Programmed, Dual
2nd-Order Continuous Lowpass Filter
MAX270/MAX271
Typical Operating Characteristics (continued)
MAX270 toc07
f
IN/
f
C
GAIN (dB)
0.1
-1.5
-0.5
-3.5
-2.5
-5.5
-4.5
-7.5
-6.5
+0.5
0.01 1.0
CASCADED FILTER GAIN vs. FREQUENCY
(NORMALIZED TO CUTOFF FREQUENCY)
V+ = +5V
V- = -5V
f
C
(FILTER A) = f
C
(FILTER B) =
0-127 (1-25kHz TYP)
FILTERS A AND B CASCADED
FIGURE 5
T
A
= +25˚C
MAX270 toc08
f
IN/
f
C
GAIN (dB)
1.0
-80
-20
-40
-60
0
0.01 10
CASCADED FILTER GAIN vs. FREQUENCY
(NORMALIZED TO CUTOFF FREQUENCY)
V+ = +5V
V- = -5V
f
C
(FILTER A) = f
C
(FILTER B) =
0-127 (1-25kHz TYP)
FILTERS A AND B CASCADED
FIGURE 5
T
A
= +25˚C
MAX270 toc09
F (Hz)
GAIN (dB)
1k 2k 3k
-120
-20
-40
-100
-80
-60
0
04
k
FILTER HARMONIC DISTORTION
V+ = +5V
V- = -5V
f
C
CODE = 44 (2.01kHz TYP)
f
TEST
= 390.625Hz
T
A
= +25˚C
V
IN
= 3.5V
P-P
MAX270 toc10
V+ = 5V, V- = -5V; V
IN
= 3.5V
P-P
; T
A
= +25˚C
FILTER TOTAL HARMONIC DISTORTION
PLUS NOISE vs.INPUT FREQUENCY
f
IN
(Hz)
f
C
CODE
f
C
(Hz)
(TYP)
THD PLUS
NOISE
(TYP)
190 01k -78
390
1367
4875
44
100
127
2.01k
7.01k
25k
-73
-67
-66
MAX270 toc11
V
IN
(V
P-P)
GAIN (dB)
1.0
-85
-60
-65
-70
-75
-80
0.2 8.0
FILTER TOTAL HARMONIC DISTORTION
PLUS NOISE vs. INPUT AMPLITUDE
V+ = +5V
V- = -5V
f
IN
= 390.625Hz
f
C
CODE = 44 (2.01kHz TYP)
T
A
= +25˚C
MAX270 toc14
MAX271 FILTER PLUS TRACK-AND-HOLD
SPURIOUS-FREE DYNAMIC RANGE
vs. SAMPLING FREQUENCY
f
SAMPLE
(Hz)
100k
200k
500k
f
IN
(Hz)
781
1562
3906
f
C
CODE
72
105
124
SFDR
(dB)
72
72
64
f
C
(Hz)
4.01k
8.08k
19.4k
V+ = 5V, V- = -5V; V
IN
= 3.5V
P-P
;
T/H SWITCHED AT 50kHz, 50% DUTY CYCLE; T
A
= +25˚C
MAX270 toc13
V
IN
(V
P-P)
SFDR (dB)
1.0
-85
55
65
75
0.5 8.0
MAX271 FILTER PLUS TRACK-AND-HOLD
SPURIOUS-FREE DYNAMIC RANGE
vs. INPUT AMPLITUDE
V+ = +5V
V- = -5V
f
IN
= 390Hz
f
C
CODE = 44 (2.01kHz TYP)
T
A
= +25˚C
MAX270 toc12
MAX271 FILTER PLUS TRACK-AND-HOLD
SPURIOUS-FREE DYNAMIC RANGE
vs. INPUT FREQUENCY
f
IN
(Hz)
f
C
CODE
f
C
(Hz)
(TYP)
SFDR
(dB)
195 01k 73.5
781
1562.5
3906
72
105
124
4.01k
8.08k
19.4k
69.5
66
61.5
V+ = 5V, V- = -5V; V
IN
= 3.5V
P-P
;
T/H SWITCHED AT 50kHz, 50% DUTY CYCLE; T
A
= +25˚C