Instruction Manual

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General Description

The MAX3744/MAX3745 transimpedance amplifiers pro-

vide a compact, low-power solution for communication

up to 2.7Gbps. They feature 330nA input-referred noise

at 2.1GHz bandwidth (BW) with 0.85pF input capaci-

tance. The parts also have >2mA

P-P

AC input overload.

Both parts operate from a single +3.3V supply and con-

sume 93mW. The MAX3744/MAX3745 are in a compact

30-mil x 50-mil die and require no external compensa-

tion capacitor. A space-saving filter connection is pro-

vided for positive bias to the photodiode through an

on-chip 580Ω resistor to V

. These features allow

easy assembly into a low-cost TO-46 or TO-56 header

with a photodiode.

The MAX3744 and MAX3748A receiver chip set pro-

vides an RSSI output using a Maxim-proprietary* inter-

face technique. The MAX3744 preamplifier, MAX3748A

postamplifier, and DS1858/DS1859 SFP controller meet

all the SFF-8472 digital diagnostic requirements.

Applications

Up to 2.7Gbps SFF/SFP Optical Receivers

Optimized for Small-Form-Factor Pluggable (SFP)

Optical Receivers

Features

♦ Up to 2.7Gbps (NRZ) Data Rates

♦ RSSI Implementation in 4-Pin TO46 Header

(MAX3744)

♦ 10ps

P-P

Deterministic Jitter for <100µA

P-P

Input

Current

♦ 330nA

RMS

Input-Referred Noise at 2.1GHz

Bandwidth

♦ 28mA Supply Current at +3.3V

♦ 2GHz Small-Signal Bandwidth

♦ 2.0mA

P-P

AC Overload

♦ Die Size: 30 mils x 50 mils

MAX3744/MAX3745

2.7Gbps SFP Transimpedance

Amplifiers with RSSI

________________________________________________________________ Maxim Integrated Products 1

Ordering Information

FILTER

4-PIN TO CAN

400pF

OUT+

OUT-

GND

OUT+

0.1

3.3k

Ω

IN+

IN-

RSSI

DISABLE LOS

OUT-

MAX3748A

SFP OPTICAL RECEIVER

HOST

BOARD

MOD-DEF1

MOD-DEF2

4.7kΩ

10kΩ

MAX3744

DS1858/

DS1859

3.3V

Typical Application Circuit

19-2927; Rev 0; 7/03

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at

1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

**Dice are guaranteed to operate from -40°C to +85°C, but are

tested only at T

= +25°C.

PART TEMP RANGE PIN-PACKAGE

MAX3744E/D -40°C to +85°C Dice**

MAX3745E/D -40°C to +85°C Dice**

*Patent pending

Summary of content (10 pages)

PAGE 1
9-2927; Rev 0; 7/03 2.7Gbps SFP Transimpedance Amplifiers with RSSI Features ♦ Up to 2.7Gbps (NRZ) Data Rates ♦ RSSI Implementation in 4-Pin TO46 Header (MAX3744) ♦ 10psP-P Deterministic Jitter for <100µAP-P Input Current ♦ 330nARMS Input-Referred Noise at 2.1GHz Bandwidth ♦ 28mA Supply Current at +3.3V ♦ 2GHz Small-Signal Bandwidth ♦ 2.0mAP-P AC Overload ♦ Die Size: 30 mils x 50 mils Applications Ordering Information Up to 2.
PAGE 2
MAX3744/MAX3745 2.7Gbps SFP Transimpedance Amplifiers with RSSI ABSOLUTE MAXIMUM RATINGS Power-Supply Voltage (VCC) .................................-0.5V to +6.0V Continuous CML Output Current (OUT+, OUT-) ............................................. -25mA to +25mA Continuous Input Current (IN)...............................-4mA to +4mA Continuous Input Current (FILTER).......................-8mA to +8mA Operating Junction Temperature Range (TJ) ....
PAGE 3
2.7Gbps SFP Transimpedance Amplifiers with RSSI (VCC = +2.97V to +3.63V and TA = -40°C to +85°C. Typical values are at VCC = +3.3V, source capacitance (CIN) = 0.85pF, and TA = +25°C, unless otherwise noted.
PAGE 4
Typical Operating Characteristics (VCC = +3.3V, CIN = 0.85pF, TA = +25°C, unless otherwise noted.) INPUT-REFERRED NOISE vs. TEMPERATURE 600 CIN = 1.5pF 500 CIN = 0.85pF 400 CIN = 0.5pF 300 BW = 2.1GHz 700 600 70 GAIN (dB) 700 MAX3744 toc02 INPUT-REFERRED NOISE (nARMS) UNFILTER FREQUENCY RESPONSE 75 800 INPUT-REFERRED NOISE (nARMS) MAX3744 toc01 800 500 CIN = 1.5pF MAX3744 toc03 INPUT-REFERRED NOISE vs. TEMPERATURE 65 60 400 CIN = 0.85pF 55 300 CIN = 0.
PAGE 5
2.7Gbps SFP Transimpedance Amplifiers with RSSI SUPPLY CURRENT vs. TEMPERATURE MAX3745 50 40 30 20 -25 10 -30 0 0 500 1000 1500 2000 2500 3000 3500 4000 -20 TA = +85°C 400 350 300 0 20 40 60 80 -50 100 -100 -50 0 50 100 TEMPERATURE (°C) INPUT CURRENT (mAP-P) BANDWIDTH vs. TEMPERATURE EYE DIAGRAM TEMPERATURE = +100°C INPUT = 20µAP-P DATA RATE = 2.7Gbps MAX3744 toc15 MAX3744 toc14 4.0 3.
PAGE 6
2.7Gbps SFP Transimpedance Amplifiers with RSSI MAX3744/MAX3745 Pin Description MAX3744/ MAX3745 BOND PAD NAME 1, 3 VCC 2, 7 N.C. 4 IN 5 FILTER 6, 10 GND Supply Ground 8 OUT- Inverting Data Output. Current flowing into IN causes the voltage at OUT- to decrease. For the MAX3744, the common mode between OUT+ and OUT- is proportional to the average input current. 9 OUT+ Noninverting Data Output. Current flowing into IN causes the voltage at OUT+ to increase.
PAGE 7
2.7Gbps SFP Transimpedance Amplifiers with RSSI AMPLITUDE MAX3744/MAX3745 AMPLITUDE INPUT FROM PHOTODIODE TIME TIME OUTPUT (SMALL SIGNALS) INPUT AFTER DC CANCELLATION OUTPUT (LARGE SIGNALS) Figure 2. MAX3744/MAX3745 Limited Output Figure 3. DC Cancellation Effect on Input Voltage Amplifier Stage The voltage amplifier stage provides gain and converts the single-ended input to differential outputs.
PAGE 8
MAX3744/MAX3745 2.7Gbps SFP Transimpedance Amplifiers with RSSI The MAX3744 preamp measures the average photodiode current and provides the information to the output common mode. The MAX3748A RSSI detect block senses the common-mode DC level of input signals IN+ and IN- and provides a ground-level-referenced output signal of the photodiode current. The advantage of this implementation is that it allows the TIA to be packaged in a low-cost conventional 4-pin TO-46 header.
PAGE 9
2.7Gbps SFP Transimpedance Amplifiers with RSSI Photodiode Filter Supply voltage noise at the cathode of the photodiode produces a current I = CPD ∆V/∆t, which reduces the receiver sensitivity (C PD is the photodiode capacitance.) The filter resistor of the MAX3744/MAX3745, combined with an external capacitor, can be used to reduce this noise (see the Typical Application Circuit). Current generated by supply noise voltage is divided between CFILTER and CPD.
PAGE 10
2.7Gbps SFP Transimpedance Amplifiers with RSSI MAX3744/MAX3745 Chip Topography GND VCC 1 N.C. 2 VCC 3 IN 4 FILTER 5 MAX3744 MAX3745 10 9 OUT+ 0.03in (0.76mm) 6 7 GND N.C. 8 OUT- 0.05in (1.26mm) Pad Coordinates Chip Information PAD COORDINATES (µm) X COORDINATES (µm) Y 1 1.4 495.6 2 0 336 3 0 224 4 0 112 5 0 0 6 494.2 -1.4 7 865.2 -1.4 8 1005.2 -1.4 9 1005.2 495.6 10 490 495.