ML2111CIP View Datasheet(PDF) - Micro Linear Corporation
Part Name
Description
MFG CO.
'ML2111CIP' PDF : 26 Pages View PDF
OPERATION MODES (Continued)
above the center frequency through the resistor ratio Rh/
Rl. Because of this, modes 3 and 3a are the most versatile
and useful modes for cascading second order sections to
obtain high order elliptic filters. For very selective
bandpass/bandreject filters the mode 3a approach , as in
Figure 24, yields better dynamic range since the external
op amp helps to optimize the dynamics of the output
nodes of the ML2111.
Modes 4 and 5 are useful for constructing allpass res-
ponse filters. Mode 4, Figure 25, gives an allpass
response, but due to the sampled nature of the filter, a
slight 0.5 dB peaking can occur around the center
ML2111
frequency. Mode 4a (Figure 26) gives a non-inverting
output, but requires an external op amp. Mode 5 is
recommended if this response is unacceptable. Mode 5
(Figure 27) gives a flatter response than mode 4 if R1 = R2
= 0.02 ´ R4.
Modes 6 and 7 are used to construct 1st order filters.
Mode 6a (Figure 28) gives a lowpass and a highpass
single pole response. Mode 6b (Figure 29) gives an
inverting and non-inverting lowpass single pole filter
response. Mode 7 (Figure 30) gives an allpass and lowpass
single pole response.
R3
R2
R1 = R2
VIN
4 (17) +
AP
S1A
3 (18) 5 (16)
+Σ
BP
2 (19)
LP
1 (20)
SA/B
6
15
V+
0 5 fo
=
fCLK
100 50
;
Q
=
R3
R2
;
HOAP
=
-
R2
R1
;
HOLP
= -2;
HOBP
= -2
R3
R2
Figure 25. Mode 4: 2nd Order Filter Providing Allpass, Bandpass, Lowpass — ½ ML2111
R4
R3
R2
R1
VIN
4 (17) +
HP
S1A
3 (18) 5 (16)
+Σ
SA/B
6
15
V-
BP
2 (19)
LP
1 (20)
R
2R
R5
External
Op Amp
+
f0
=
fCLK
100(50)
R2 ;Q = R3
R4 R2
R2 ;
R4
HOAP
=
R5
2R
;HOHP
=
- R2 ;
R1
HOLP
=
-
R4
R1
;
HOBP
=
-
R3
R1
Figure 26. Mode 4a: 2nd Order Filter Providing Highpass, Bandpass, Lowpass, Allpass — ½ ML2111
19
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