ML2111CIP datasheet(14/26 Pages) MICRO-LINEAR

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ML2111

4. Notch function: available at N/AP/HPA and N/AP/HPB

for several modes of operation.

()

(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.

OAP

()

(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.

FILTER FUNCTION DEFINITIONS

V+

SA/B

1 (20)

4 (17)

VIN

BP1

S1A

5 (16)

BP2

3 (18)

2 (19)

VIN

S1A

V+

SA/B

5 (16)

3 (18)

2 (19)

1 (20)

4 (17)

½ ML2111

Figure 15. Mode 1: 2nd Order Filter Providing Notch,

Bandpass, Lowpass

Figure 16. Mode 1a: 2nd Order Filter Providing

Bandpass, Lowpass

ff H

CLK

nOLP

OBP

100 50

()

;;

;

ON1

;

CLK

OBP

100 50

= -

()

;;

;

non inverting H

OBP

OLP

= -

();

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.

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