ML2111CIP View Datasheet(PDF) - Micro Linear Corporation
Part Name
Description
Manufacturer
ML2111CIP Datasheet PDF : 26 Pages
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ML2111
FILTER FUNCTION DEFINITIONS
4. Notch function: available at N/AP/HPA and N/AP/HPB
for several modes of operation.
4 9 G(s) = HON2
s2 +
s2 + wn2
s w0
Q
+
w
2
0
(4)
HON2 = Gain of the notch output for f ® fCLK/2.
HON1 = Gain of the HP output for f ® 0
fn = wn/2p. The frequency of the notch occurrence is
fn.
5. Allpass function: available at N/AP/HPA and N/AP/
HPB for modes 4 and 4a.
G(s) = HOAP
s2 -
s2 +
s w0
Q
s w0
Q
+ w02
+ w02
(5)
HOAP = Gain of the allpass output for 0 < f < fCLK/2
For allpass functions, the center frequency and the Q of
the numerator complex zero pair is the same as the
denominator. Under these conditions the magnitude
response is a straight line. In mode 5, the center
frequency fZ of the numerator complex zero pair is
different than f0. For high numerator Q's, the
magnitude response will have a notch at fZ.
OPERATION MODES
There are three basic modes of operation — Modes 1, 2,
and 3 , each of which has derivatives; and four secondary
modes of operation — Modes 4, 5, 6, and 7, each of
which also has derivatives.
In Figure 15, the input amplifier is outside the resonant
loop. Because of this, mode 1 and its derivatives (modes
1a, 1b, 1c, and 1d) are faster than modes 2 and 3.
Mode 1 provides a clock tunable notch. It is a practical
configuration for second order clock tunable bandpass/
notch filters. In mode 1, a band pass output with a very
high Q, together with unity gain can be obtained with the
dynamics of the remaining notch and lowpass outputs.
Mode 1a (Figure 16) represents the simplest hookup of the
ML2111. It is useful when voltage gain at the bandpass
output is required. However, the bandpass voltage gain is
equal to the value of Q, and second order, clock tunable,
BP resonator can be achieved with only 2 resistors. The
filter center frequency directly depends on the external
clock frequency. Mode 1a is not practical for high order
filters as it requires several clock frequencies to tune the
overall filter response.
Modes 1b and 1c, Figures 17 and 18, are similar. They
both produce a notch with a frequency which is always
equal to the filter center frequency. The notch and the
center frequency can be adjusted with an external resistor
ratio.
½ ML2111
R3
R2
R1
VIN
4 (17) +
N
S1A
3 (18) 5 (16)
+Σ
SA/B
6
15
V+
BP
2 (19)
LP
1 (20)
f0
=
fCLK
100(50)
; fn
=
f0 ;HOLP
=
-
R2
R1
;
HOBP
=
- R3 ;
R1
HON1
=
-
R2
R1
;
Q
=
R3
R2
Figure 15. Mode 1: 2nd Order Filter Providing Notch,
Bandpass, Lowpass
14
½ ML2111
R3
R2
4 (17) +
VIN
BP2
S1A
3 (18) 5 (16)
+Σ
BP1
2 (19)
LP
1 (20)
SA/B
6
15
V+
f0
=
fCLK
100(50)
;Q
=
R3
R2
;HOBP1
=
-
R3 ;
R2
HOBP2 = 1(non - inverting);HOLP = -1
Figure 16. Mode 1a: 2nd Order Filter Providing
Bandpass, Lowpass
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