TAT6254C

Fiber To The Home RF Amplifier 47–1000 MHz

12 V Standard Output Application Board Typical Performance (cont'd)

0

1

2

3

4

5

6

0

200

400

600

800

1000

1200

Frequency (MHz)

Equivalent Input Noise at Max Gain

-20 C

25 C

85 C

-85

-80

-75

-70

-65

-60

0

100

200

300

400

500

600

Frequency (MHz)

CTB

18 dBmV/Ch, 80 ch

20 dBmV/Ch, 80 ch

22 dBmV/Ch, 80 ch

18 dBmV/Ch, 40 ch

+2 dBm at 55.25MHz, 4.3% (40ch) and 3.3% (80ch) equiv inputs

20 dBmV/Ch, 40 ch

22 dBmV/Ch, 40 ch

For performance data using 5 V Output, please email sjcapplication.engineering@tqs.com.

Detailed Device Description And Application Overview

The TAT6254C integrates two low noise high gain trans-impedance

amplifiers in a differential configuration followed by an output

amplifier. It provides a low input impedance to minimize the effects

of photodiode capacitances and stray impedance affects on gain

flatness.

The TAT6254C is fabricated using high gain Gallium Arsenide

pHEMT technology developed for high-volume commercial markets.

It provides improved gain and noise compared to older MESFET

technologies and lower gain pHEMT technologies.

The TAT6254C was designed as a general purpose FTTP receiver.

While it eliminates the need for costly hand-wound parts such as

baluns and directional couplers, it allows users wide flexibility in

setting gain, tilt, and bias levels to best meet the requirements posed

by different operators and architectures. The TAT6254C provides the

flexibility to address high levels of gain required by GPON

architectures. Designers can easily modify external circuit values to

enable wider optical input ranges, such as needed in newer GPON

architectures.

The TAT6254C provides two high level outputs. One output drives an

optical tilt network while the other drives a content filter and an RF

detection circuit. The TAT6254C does not require an output balun.

Because the two equal outputs have a high level of isolation; the

TAT6254C effectively provides an integrated directional coupler with

extra gain to drive the RF detection circuit at a high level. This eases

offset voltage requirements on operational amplifiers used in the AGC

block.

Biasing

Bulk

Optic

CWDM

Reference

Content

Filter

Temp Comp

RF Detector

Tilt

AGC

RF Output

Gain

Gain Adjust

TIA

TIA

Biasing

Bulk

Optic

CWDM

Reference

Content

Filter

Temp Comp

RF Detector

Tilt

AGC

RF Output

Gain

Gain Adjust

TIA

TIA

RF AGC Solution 

Biasing

Bulk

Optic

CWDM

Reference

Temp Comp

RF Detector

AGC

Gain

Gain Adjust

Match

TIA

TIA

RF Output

Tilt

(Optional)

4:1

Xfmr

RF AGC High Output Option

 

Data Sheet: Rev A 09/14/2011

- 4 of 9 -

Disclaimer: Subject to change without notice

© 2011 TriQuint Semiconductor, Inc.

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