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ML4622, ML4624

Figure 1. The ML4622, ML4624 Configured for 20MHz Bandwidth

FUNCTIONAL DESCRIPTION

AMPLIFIER

The ML4622, ML4624 have an adjustable Bandwidth

limiting amplifier. Maximum sensitivity is achieved

through the use of a DC restoration feedback loop and

AC coupling the input. When AC coupled, the input DC

bias voltage is set by an on-chip network at about 1.7V.

These coupling capacitors, in conjunction with the input

impedance of the amplifier, establish a high pass filter

f =

1

2 1600C

L

π

(1)

Since the amplifier has a differential input, two capacitors

of equal value are required. If the signal driving the input

is single ended, one of the coupling capacitors can be tied

CF1 and CF2 create a low pass filter with the corner

frequency determined by the following equation

f =

1

2 8

C + 4pF)

H

π 00(

(2)

The above equation applies when a single capacitor is

tied between CF1 and CF2. When using two capacitors of

Although the input is AC coupled, the offset voltage

within the amplifier will be present at the amplifier’s

reduce this error a DC feedback loop is incorporated. This

negative feedback loop nulls the offset voltage, forcing

Figure 2.

Note:

If TTL OUT is used, tie GND TTL to unfiltered ground and remove L1. If TTL OUT and ECL outputs are both used, add 3K pulldown resistors at

ECL outputs.

ECL+

ECL–

TTL OUT

CMP ENABLE

TTL*

GND

GND

TTL

TTL LINK MON

CF1

CF2

THRESH

GEN

REF

*ML4624 ONLY

BIAS

ECL

CMP

TTL

CMP

AMP

LINK DETECT

0.1

+

4.7

0.1

+5V

+

4.7

L1

4.7µH

L2

4.7µH

HFBR

2416

1

4

5

8

7

10

Ω

2

6

0.01

0.01

0.1

0.1

5pF

FIBER OPTIC CABLE

0.05

∫

3