Datasheet

ManualsBrandsANALOG DEVICES ManualsLinear ICsLinear IC - Op-amp Transimpedance SOIC 8

FUNCTIONAL BLOCK DIAGRAM

10kΩ

AD8015

50Ω

BYP

–V

–OUTPUT

+OUTPUT

G = 3

G = 30

NC = NO CONNECT

50Ω

– + +V

1.7V

25.0E+3

20.0E+3

000.E+0

10.0E+6 100.0E+6 1.0E+9

15.0E+3

10.0E+3

5.0E+3

FREQUENCY – Hz

X-RESISTANCE – Ω

DIFFERENTIAL

SINGLE-ENDED

Figure 1. Differential/Single-Ended Transimpedance vs.

Frequency

5.0

4.5

4.0

3.5

3.0

2.5

2.0

100.0E+620.0E+6000.0E+0 80.0E+660.0E+640.0E+6

FREQUENCY – Hz

EQUIVALENT INPUT CURRENT NOISE – pA

√

3.0pF

2.0pF

1.5pF

1.0pF

0.5pF

Figure 2. Noise vs. Frequency (SO-8 Package with

Added Capacitance)

REV. A

Information furnished by Analog Devices is believed to be accurate and

reliable. However, no responsibility is assumed by Analog Devices for its

use, nor for any infringements of patents or other rights of third parties

which may result from its use. No license is granted by implication or

otherwise under any patent or patent rights of Analog Devices.

Wideband/Differential Output

Transimpedance Amplifier

AD8015

FEATURES

Low Cost, Wide Bandwidth, Low Noise

Bandwidth: 240 MHz

Pulse Width Modulation: 500 ps

Rise Time/Fall Time: 1.5 ns

Input Current Noise: 3.0 pA/√

Hz @ 100 MHz

Total Input RMS Noise: 26.5 nA to 100 MHz

Wide Dynamic Range

Optical Sensitivity: –36 dBm @ 155.52 Mbps

Peak Input Current: 6350 mA

Differential Outputs

Low Power: 5 V @ 25 mA

Wide Operating Temperature Range: –408C to +858C

APPLICATIONS

Fiber Optic Receivers: SONET/SDH, FDDI, Fibre Channel

Stable Operation with High Capacitance Detectors

Low Noise Preamplifiers

Single-Ended to Differential Conversion

I-to-V Converters

PRODUCT DESCRIPTION

The AD8015 is a wide bandwidth, single supply transimpedance

amplifier optimized for use in a fiber optic receiver circuit. It is a

complete, single chip solution for converting photodiode current

into a differential voltage output. The 240MHz bandwidth enables

AD8015 application in FDDI receivers and SONET/SDH

receivers with data rates up to 155 Mbps. This high bandwidth

supports data rates beyond 300 Mbps. The differential outputs

drive ECL directly, or can drive a comparator/ fiber optic post

amplifier.

In addition to fiber optic applications, this low cost, silicon al-

ternative to GaAs-based transimpedance amplifiers is ideal for

systems requiring a wide dynamic range preamplifier or single-

ended to differential conversion. The IC can be used with a

standard ECL power supply (–5.2 V) or a PECL (+5 V) power

supply; the common mode at the output is ECL compatible.

The AD8015 is available in die form, or in an 8-pin SOIC

package.

One Technology Way, P.O. Box 9106, Norwood, 02062-9106, U.S.A.

Tel: 617/329-4700 Fax: 617/326-8703

Summary of content (8 pages)

PAGE 1
a Wideband/Differential Output Transimpedance Amplifier AD8015 FUNCTIONAL BLOCK DIAGRAM FEATURES Low Cost, Wide Bandwidth, Low Noise Bandwidth: 240 MHz Pulse Width Modulation: 500 ps Rise Time/Fall Time: 1.5 ns Input Current Noise: 3.0 pA/√Hz @ 100 MHz Total Input RMS Noise: 26.5 nA to 100 MHz Wide Dynamic Range Optical Sensitivity: –36 dBm @ 155.
PAGE 2
AD8015–SPECIFICATIONS (SO Package @ T = +258C and V A S = +5 V, unless otherwise noted) AD8015AR Typ Parameter Conditions Min DYNAMIC PERFORMANCE Bandwidth Pulse Width Modulation Rise and Fall Time Settling Time1 3 dB 10 µA to 200 µA Peak 10% to 90% to 3%, 0.5 V Diff Output Step 180 240 500 1.5 3 MHz ps ns ns ± 2.5%, Nonlinearity Saturation 155 Mbps, Avg Power Die, by Design SOIC, by Design +VS to IIN and VBYP ± 25 ± 200 ± 30 ± 350 –36 0.2 0.4 1.
PAGE 3
AD8015 PIN CONFIGURATION +VS +VS 1.7V AD8015 AD8015 NC 1 1 8 +VS 2 7 +OUTPUT +1 G=3 50Ω – + 50Ω R CLOCK RECOVERY – + 4 +VS CLK DATA QUANTIZER +1 . 5 –VS +VS 6 LPF: 3dB@ 0.7 x F G=3 3 6 –OUTPUT +1 VBYP 4 +1 G = 30 G = 30 NC 3 7 LPF: R 3dB@ 0.7 x F 50Ω 50Ω IIN 2 V1 8 10kΩ 10kΩ R > 40Ω C1 >100pF 4.5V < VS < 11V 5 1.7V 1.7V C1 NC = NO CONNECT Figure 3.
PAGE 4
AD8015 SONET OC-3 SENSITIVITY ANALYSIS Sensitivity (minimum power level) = 492/0.85 nW OC-3 Minimum Bandwidth = 0.7 × 155 MHz ≈ 110 MHz = 579 nW (peak) Total Current Noise = (π/2) × 26.5 nA = –32.4 dBm (peak) = 42 nA (assuming single pole response) = –35.4 dBm (average) To maintain a BER < 1 × 10–10 (1 error per 10 billion bits): The FDDI specification allows for a minimum power level of –28 dBm peak, or –31 dBm average. Using the AD8015 provides 4.4 dB margin.
PAGE 5
AD8015 1.5 9 +85°C +85°C + 25°C 0.5 – 40°C –40°C AND 0°C GAIN – dB OUTPUT VOLTAGE – Volts 1.0 0 5 4k –0.5 VOUT 0 IN 50Ω AD8015 –1.0 –1.5 –100 –80 –60 –40 –20 0 20 40 60 80 100 1 INPUT CURRENT – µA 10 Figure 6. Differential Output vs. Input Current Figure 9. Gain vs. Frequency 0 10 +85°C +25°C PIN 7 GROUP DELAY – ns OUTPUT VOLTAGE – Volts –0.5 –1.0 –40°C –1.5 1000 100 FREQUENCY – MHz –40°C PIN 6 5V, +25°C 0 –2.0 +25°C +85°C –2.
PAGE 6
AD8015 APPLICATION 155 Mbps Fiber Optic Receiver 100 The AD8015 and AD807 can be used together for a complete 155 Mbps Fiber Optic Receiver (Transimpedance Amplifier, Post Amplifier with Signal Detect Output, and Clock Recovery and Data Retiming) as shown in Figure 16. PIN 7 The PIN diode front end is connected to a single mode, 1300 nm laser source. The PIN diode has 3.3 V reverse bias, 0.8 A/W responsivity, 0.7 pF capacitance, and 2.5 GHz bandwidth.
PAGE 7
AD8015 C1 0.1µF SDOUT TP7 TP8 DATAOUTN DATAOUTP C2 R1 R2 0.1µF 100 100 C3 0.1µF C4 0.1µF R11 R10 154 154 R5 100 R6 100 R8 100 CLKOUTP C5 0.1µF C8 R4 100 R11 154 1 DATAOUTN 2 DATAOUTP 3 VCC2 4 CLKOUTN 5 CLKOUTP 6 VCC1 7 CF1 C7 R7 100 CLKOUTN R3 100 C1 100pF R12 154 C6 0.1µF TP1 CD 8 TP2 DAMPING CAP,0.22µF GND TP4 16 R17 3.65k SDOUT 15 C11 VEE AVCC 14 PIN 13 NIN 12 AVCC 11 THRADJ 10 CF2 AD807 R13 THRADJ TP5 C15 0.
PAGE 8
AC COUPLED PHOTODIODE APPLICATION FOR IMPROVED DYNAMIC RANGE and typical sensitivity of –35 dBm. AC coupling the input also results in improved pulse width modulation performance. AC coupling the photodiode current input to the AD8015 (Figure 17) extends fiber optic receiver overload by 3 dB while sacrificing only 1 dB of sensitivity (increasing receiver dynamic range by 2 dB).