Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsLinear ICsLinear IC - Custom amplification Limiting amplifier TQFN 16 EP

MAX3748H

Compact, Low-Power, 155Mbps to 4.25Gbps

Limiting Amplifier

�� Maxim Integrated Products 1

General Description

The MAX3748H multirate limiting amplifier functions as

a data quantizer for SONET, Fibre Channel, and Gigabit

Ethernet optical receivers. The amplifier accepts a wide

range of input voltages and provides constant-level

current-mode logic (CML) output voltages with controlled

edge speeds.

A received-signal-strength indicator (RSSI) is available

when the MAX3748H is combined with the MAX3744

SFP transimpedance amplifier (TIA). A receiver consist-

ing of the MAX3744 and the MAX3748H can provide up

to 19dB RSSI dynamic range. Additional features include

a programmable loss-of-signal (LOS) detect, an optional

disable function (DISABLE), and an output signal polar-

ity reversal (OUTPOL). Output disable can be used to

implement squelch.

The combination of the MAX3748H and the MAX3744

allows for the implementation of all the small-form-factor

SFF-8472 digital diagnostic specifications using a stan-

dard 4-pin TO-46 header. The MAX3748H is packaged in

a 3mm x 3mm, 16-pin thin QFN package with an exposed

pad.

Features

S SFP Reference Design Available

S 16-Pin TQFN Package with 3mm x 3mm Footprint

S Single 3.3V Supply Voltage

S 86ps Rise and Fall Time

S Loss of Signal with Programmable Threshold

S RSSI Interface (with MAX3744 TIA)

S Output Disable

S Polarity Select

S 8.7ps

P-P

Deterministic Jitter (4.25Gbps)

Applications

Gigabit Ethernet SFF/SFP Transceiver Modules

Fibre Channel SFF/SFP Transceiver Modules

Multirate OC-3 to OC-48-FEC SFF/SFP

Transceiver Modules

Typical Operating Circuits

Typical Operating Circuits continued at end of data sheet.

19-5954; Rev 0; 7/11

Ordering Information appears at end of data sheet.

For related parts and recommended products to use with this part, refer to: www.maxim-ic.com/MAX3748H.related

E V A L U A T I O N K I T A V A I L A B L E

MAX3744 TIA

3-INPUT DIAGNOSTIC

MONITOR

3kΩ

0.1µF

IN+

IN-

RSSI TH DISABLE LOS

0.1µF

OUTPOL CAZ1 CAZ2V

GND

4.7kΩ TO 10kΩ

LOS

CC_HOST

OUT+

50Ω

0.1µF

OUT-

50Ω

0.1µF

SerDes

SUPPLY FILTER HOST FILTER

CC_RX

4-PIN TO HEADER

HOST BOARDSFP OPTICAL RECEIVER

MAX3748H

DS1858

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,

or visit Maxim’s website at www.maxim-ic.com.

Summary of content (14 pages)

PAGE 1
9-5954; Rev 0; 7/11 EVALUATION KIT AVAILABLE MAX3748H Compact, Low-Power, 155Mbps to 4.25Gbps Limiting Amplifier General Description Features The MAX3748H multirate limiting amplifier functions as a data quantizer for SONET, Fibre Channel, and Gigabit Ethernet optical receivers. The amplifier accepts a wide range of input voltages and provides constant-level current-mode logic (CML) output voltages with controlled edge speeds.
PAGE 2
MAX3748H Compact, Low-Power, 155Mbps to 4.25Gbps Limiting Amplifier ABSOLUTE MAXIMUM RATINGS Power-Supply Voltage Range (VCC).....................-0.5V to +6.0V Voltage Range at IN+, IN-.............. (VCC - 2.4V) to (VCC + 0.5V) Voltage Range at DISABLE, OUTPOL, RSSI, CAZ1, CAZ2, LOS, TH................. -0.5V to (VCC + 0.5V) Current Range into LOS....................................... -1mA to +9mA Differential Input Voltage (IN+ - IN-).....................................2.
PAGE 3
MAX3748H Compact, Low-Power, 155Mbps to 4.25Gbps Limiting Amplifier ELECTRICAL CHARACTERISTICS (continued) (VCC = 2.97V to 3.63V, ambient temperature = -40°C to +85°C, CML output load is 50Ω to VCC, CAZ = 0.1μF, typical values are at TA = +25°C, VCC = 3.3V, unless otherwise specified. The data input transition time is controlled by a 4th-order Bessel filter with f-3dB = 0.75 x 2.667GHz for all data rates of 2.667Gbps and below, and with f-3dB = 0.75 x data rate for data rates > 3.2Gbps.
PAGE 4
MAX3748H Compact, Low-Power, 155Mbps to 4.25Gbps Limiting Amplifier ELECTRICAL CHARACTERISTICS (continued) (VCC = 2.97V to 3.63V, ambient temperature = -40°C to +85°C, CML output load is 50Ω to VCC, CAZ = 0.1μF, typical values are at TA = +25°C, VCC = 3.3V, unless otherwise specified. The data input transition time is controlled by a 4th-order Bessel filter with f-3dB = 0.75 x 2.667GHz for all data rates of 2.667Gbps and below, and with f-3dB = 0.75 x data rate for data rates > 3.2Gbps.
PAGE 5
MAX3748H Compact, Low-Power, 155Mbps to 4.25Gbps Limiting Amplifier Typical Operating Characteristics (TA = +25°C and VCC = 3.3V, unless otherwise noted.) 60 50 40 30 20 10 0 600 500 400 300 6 5 4 3 200 2 100 1 2 1 3 4 5 MAX3748H toc03 8 7 0 6 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 DIFFERENTIAL INPUT (mVP-P) TEMPERATURE (°C) RANDOM JITTER vs. INPUT AMPLITUDE BIT-ERROR RATIO vs. INPUT VOLTAGE DETERMINISTIC JITTER vs. INPUT COMMON-MODE VOLTAGE (VCC TO VCC - 0.
PAGE 6
MAX3748H Compact, Low-Power, 155Mbps to 4.25Gbps Limiting Amplifier Typical Operating Characteristics (continued) (TA = +25°C and VCC = 3.3V, unless otherwise noted.) OUTPUT EYE DIAGRAM AT +100C (MINIMUM INPUT) ASSERT/DEASSERT LEVELS vs. RTH MAX3748H toc11 MAX3748H toc10 100 ASSERT/DEASSERT (mVP-P) 3.2Gbps, 223 - 1 PRBS, 5mVP-P 2.7Gbps, 223 - 1 PRBS, 1200mVP-P 100mV/div 100mV/div MAX3748H toc12 OUTPUT EYE DIAGRAM WITH MAXIMUM INPUT (DATA RATE OF 2.
PAGE 7
MAX3748H Compact, Low-Power, 155Mbps to 4.25Gbps Limiting Amplifier Pin Configuration TOP VIEW VCC OUT+ OUT- OUTPOL 12 RSSI 13 CAZ2 14 11 10 9 8 GND 7 LOS 6 DISABLE 5 TH MAX3748H CAZ1 15 GND 16 EP + 1 2 3 4 VCC IN+ IN- VCC TQFN (3mm × 3mm) Pin Description PIN NAME 1, 4, 12 VCC Supply Voltage FUNCTION 2 IN+ Noninverted Input Signal, CML 3 IN- Inverted Input Signal, CML 5 TH Loss-of-Signal Threshold Pin. Resistor to ground (RTH) sets the LOS threshold.
PAGE 8
MAX3748H Compact, Low-Power, 155Mbps to 4.25Gbps Limiting Amplifier Pin Description (continued) PIN NAME FUNCTION 15 CAZ1 Offset Correction Loop Capacitor Connection. A capacitor connected between this pin and CAZ2 extends the time constant of the offset correction loop. Typical value of CAZ is 0.1FF. The offset correction is disabled when the CAZ1 and CAZ2 pins are shorted together. — EP Exposed Pad. Connect the exposed pad to board ground for optimal electrical and thermal performance.
PAGE 9
MAX3748H Compact, Low-Power, 155Mbps to 4.25Gbps Limiting Amplifier Detailed Description The MAX3748H limiting amplifier consists of an input buffer, a multistage amplifier, offset correction circuitry, an output buffer, power-detection circuitry, and signaldetect circuitry (see the Functional Diagram). Input Buffer The input buffer is shown in Figure 3. It provides 50Ω termination for each input signal IN+ and IN-.
PAGE 10
MAX3748H Compact, Low-Power, 155Mbps to 4.25Gbps Limiting Amplifier CML Output Buffer The MAX3748H limiting amplifier’s CML output provides high tolerance to impedance mismatches and inductive connectors. The output current is approximately 18mA. The output is disabled by connecting the DISABLE pin to VCC. If the LOS pin is connected to the DISABLE pin, the outputs OUT+ and OUT- are at a static voltage (squelch) whenever the input signal level drops below the LOS threshold.
PAGE 11
MAX3748H Compact, Low-Power, 155Mbps to 4.25Gbps Limiting Amplifier Select the Offset-Correction Capacitor The capacitor between CAZ1 and CAZ2 determines the time constant of the signal path DC offset cancellation loop. To maintain stability, it is important to keep a onedecade separation between fIN and the low-frequency cutoff (fOC) associated with the DC offset cancellation circuit. For ATM/SONET or other applications using scrambled NRZ data, fIN < 32kHz, so fOCMAX < 3.2kHz. Therefore, CAZ = 0.
PAGE 12
MAX3748H Compact, Low-Power, 155Mbps to 4.25Gbps Limiting Amplifier Typical Operating Circuits (continued) SFP OPTICAL RECEIVER VCC (3.3V OR APD REFERENCE VOLTAGE) HOST BOARD VCC (3.3V) SUPPLY FILTER 0.1µF HOST FILTER VCC_RX 5-PIN TO HEADER OUTPOL PIN OR APD VCC CAZ1 CAZ2 IN+ MAX3744 TIA OUT+ OUT- IN- 0.1µF 50Ω SerDes 0.1µF 50Ω MAX3748H RSSI GND TH DISABLE LOS 4.7kΩ TO 10kΩ VCC_HOST RTH DS1858 3-INPUT DIAGNOSTIC MONITOR LOS R1 3kΩ C1 0.1µF SFP OPTICAL RECEIVER HOST BOARD VCC (3.
PAGE 13
MAX3748H Compact, Low-Power, 155Mbps to 4.25Gbps Limiting Amplifier Chip Information Package Information Ordering Information For the latest package outline information and land patterns (footprints), go to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status.
PAGE 14
MAX3748H Compact, Low-Power, 155Mbps to 4.25Gbps Limiting Amplifier Revision History REVISION NUMBER REVISION DATE 0 7/11 DESCRIPTION Initial release PAGES CHANGED — Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.