Applications Information

Optical Hysteresis

In an optical receiver, the electrical power change at the

limiting amplifier is 2 times the optical power change.

As an example, if a receiver’s optical input power (x)

increases by a factor of two, and the preamplifier is lin-

ear, then the voltage input to the limiting amplifier also

increases by a factor of two.

The optical power change is 10log(2x / x) = 10log(2) =

+3dB.

At the limiting amplifier, the electrical power change is:

The MAX3272 typical voltage hysteresis is 3.3dB. This

provides an optical hysteresis of 1.65dB.

10log

2V

/ R

V/ R

10log(2 )

20log(2)

6dB

IN

2

IN

IN

2

IN

2

()

==

= +

+3.3V, 2.5Gbps Low-Power

Limiting Amplifiers

_______________________________________________________________________________________

9

1

2

3

4

5

15

14

13

12

11

20

19

18

17

16

67

8

9

10

GND

IN+

IN-

GND

NOTE: EXPOSED PAD MUST BE CONNECTED TO SUPPLY GROUND.

TH

OUT+

OUT-

LEVEL

TOP VIEW

QFN*

MAX3272/

MAX3272A

1

2

3

4

5

15

14

13

12

11

20

19

18

17

16

67

8

9

10

GND

IN+

IN-

GND

NOTE: EXPOSED PAD MUST BE CONNECTED TO SUPPLY GROUND.

TH

OUT+

OUT-

LEVEL

THIN QFN*

MAX3272A

+

Pin Configuration

Pad Coordinates

PAD

NAME

COORDINATES (µm)

1

GND

47, 836

2

IN+

47, 603

3

IN-

47, 425

4

GND

47, 237

5TH

47, 47

255, -154

7

CLOS

436, -154

8

SQUELCH

645, -154

9

LOS

850, -154

10

LOS

1063, -154

11

LEVEL

1331, 37

12

1331, 212

13

OUT-

1331, 421

14

OUT+

1331, 573

15

1331, 780

16

OUTPOL

1119, 1042

17

GND

957, 1042

18

CAZ2

773, 1042

19

CAZ1

583, 1042

20

N.C.

422, 1042

21

268, 1042

Coordinates are for the center of the pad.

Coordinate 0, 0 is the lower left corner of the passivation open-

ing for pad 5.