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參數(shù)資料
| 型號： | SA5222 |
| 廠商： | NXP Semiconductors N.V. |
| 元件分類： | 運動控制電子 |
| 英文描述： | Low-Power FDDI Transimpedance Amplifier(低功耗FDDI互阻抗放大器) |
| 中文描述： | 低功耗FDDI的互阻抗放大器（低功耗FDDI的互阻抗放大器） |
| 文件頁數(shù)： | 2/12頁 |
| 文件大?。?/td> | 270K |
| 代理商： | SA5222 |
Philips Semiconductors Data Communications Products
Applications Note
AN4003
Fiber optic receiver applications note
October 12, 1992
2
capacitance
will lower
the input stage bandwidth. This will also
increase
the noise gain, however. The shunt capacitance acts
inversely with increasing frequency to increase the gain of the
amplifier to internal noise currents.
The input stage is followed by a differential buffer driver which
provides the necessary interface and level shifting for the output
emitter followers (see Figure 3). The second stage converts the
single-ended input signal to a differential signal raised to a common
mode voltage of 3.2V. The amplifier has a source/sink output
capability of 2mA. The second stage provides a gain of slightly over
two. NPN current sources are bandgap referenced to provide highly
stable biasing in the amplifier giving it an advantage in power supply
rejection and linearity.
The SA5222 differential output resistance is typically 60
and is,
therefore, capable of driving low impedance circuitry. However, the
output voltage of the SA5222 is 3.2V which limits the external DC
load resistance to ground to a value which does not draw more than
the rated 2mA of sink current. It is typically necessary to include
capacitive coupling between the SA5222 and the post amplifier in
order to allow the threshold comparators to automatically detect the
bit amplitude and provide proper level conversion independent of
preamp DC offset.
Figure 4. NE/SA5224 Postamplifier Output Disable Using Jam Functions
D
OUT
D
OUT
JAM
ST
ST
INPUT
AMP
ECL
JAM
BUFFER
SD
BUFFER
REF
(4)
(5)
(15)
(16)
(10)
(9)
(8)
(12)
(13)
éééé
éééé
éééé
éééé
DATA
IN
V
TH
D
O
D
O
ST
SIGNAL
INPUT
V
TH
LVL
DET
(7)
C
F
Data Out Structure
(Typical)
V
CC
15
15
R
L
R
E
V
CC
Input Sensitivity and Signal-to- Noise Ratio
Example of Optical Conversion gain.
Consider a 10
μ
W optical signal incident upon a 0.45A/Watt
responsivity PIN diode. This corresponds to –20dB optical relative
to 1mW (-20dBmo*). The current generated at the input node of the
SA5222 is 4.5
μ
A. The resultant differential output voltage is
4.5 A
16.6k
75mV
P
P
between Pins 6 and 7.
The dynamic signal-to-noise ratio at this level is calculated below
using the rated 1.8pA/
√
Hz over a 150MHz bandwidth
20 log
(75
10
3
) V
P
P
(1.8
10
12
)
150
10
6
16.6K
47dB
Whereas, a 1
μ
W (–30dBmo) input into a typical 0.3A/Watt
responsivity photo diode or PIN will result in a theoretical
signal-to-noise ratio of
20 log
5
10
3
V
P
P
(22
10
9
A
RMS
) 16.6k V
RMS
23dB
This does not include the optical noise of the fiber or the receiver
diode. In this case the SA5222 output voltage due to the 1
μ
W
optical input signal is 5mV
P-P
. (NOTE: A 12:1 ratio or 21.6dB
corresponds to a BER of 10
–9
.)
*NOTE: dBmo = dBm optical relative to 1mW.
Postamplifier Selection (NE/SA5224 and 5225)
In selecting the correct signal interface to meet user data
communications system specifications, two different devices are
available to the designer. For the Fiber Data Distributed Interface
(FDDI), the NE/SA5224 is recommended. This device provides
100k ECL compatibility for the differential data output, Status output
and Jam input.
For industrial fiber communications applications, the NE/SA5225 is
recommended. It provides 10k ECL compatibility. With the
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| SA5223 | Wide Dynamic Range AGC Transimpedance Amplifier (150MHz)(寬動態(tài)范圍AGC互阻抗放大器(150MHz)) |
| SA5223D | Wide dynamic range AGC transimpedance amplifier 150MHz |
| SA5230FE | Low Voltage Operational Amplifier |
| SA5230 | Low voltage operational amplifier(低壓運算放大器) |
| SA5230D | Low Voltage Operational Amplifier |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SA5222D | 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Low-power FDDI transimpedance amplifier |
| SA5223 | 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Wide dynamic range AGC transimpedance amplifier 150MHz |
| SA5223D | 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Wide dynamic range AGC transimpedance amplifier 150MHz |
| SA5224 | 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:FDDI fiber optic postamplifier |
| SA5224D | 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:FDDI fiber optic postamplifier |
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