- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄384665 > MAX3664 (Maxim Integrated Products, Inc.) Single LVDS Transmitter 5-SOT-23 -40 to 85 PDF資料下載
參數(shù)資料
| 型號(hào)： | MAX3664 |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | Single LVDS Transmitter 5-SOT-23 -40 to 85 |
| 中文描述： | 622Mbps、超低功耗、3.3V互阻前置放大器，用于SDH/SONET |
| 文件頁數(shù)： | 6/12頁 |
| 文件大小： | 236K |
| 代理商： | MAX3664 |
M
In a system where the photodiode responsivity is
0.9A/W and the extinction ratio is 10, the MAX3664/
MAX3675 receiver with 670nA gain sensitivity will deliv-
er a fully limited output for signals of average optical
power larger than:
(600nA / 0.9A/W)(1 / 2)(11 / 9) = 407nW
-33.9dBm
Sensitivity is a key specification of the receiver module.
The ITU/Bellcore specifications for SDH/SONET
receivers require a link sensitivity of -27dBm with a bit
error rate (BER) of 1E - 10. There is an additional 1dB
power penalty to accommodate various system losses;
therefore, the sensitivity of a 622Mbps receiver must be
better than -28dBm.
Although several parameters affect sensitivity (such as
the quantizer sensitivity and preamplifier gain, as previ-
ously discussed), most fiber optic receivers are designed
so that noise is the dominant factor. Noise from the high-
gain transimpedance amplifier, in particular, determines
the sensitivity. The noise generated by the MAX3664 can
be modeled with a Gaussian distribution. In this case, a
BER of 1E - 10 corresponds to a peak-to-peak signal
amplitude to RMS noise ratio (SNR) of 12.7. The
MAX3664’s typical input-referred noise, i
n
, (bandwidth-
limited to 470MHz) is 55nA
RMS
. Therefore, the minimum
input for a BER of 1E - 10 is (12.7 x 55nA) = 700nAp-p.
Rearranging the previous equations in these terms
results in the following relation:
Optical Sensitivity (dBm) =
-10log[(i
n
/
ρ
)(SNR)(1/2)(r
e
+ 1) / (r
e
- 1)(1000)]
At room temperature, with r
e
= 10, SNR = 12.7, i
n
=
55nA, and
ρ
= 0.9A/W, the MAX3664 sensitivity is
-33.2dBm. At +85°C, noise increases to 62nA and sen-
sitivity decreases to -32.7dBm. The MAX3664 provides
4.7dB margin over the SDH/SONET specifications, even
at +85°C.
The largest allowable input to an optical receiver is called
the input overload. The MAX3664’s largest input current
(I
max
) is 300μAp-p, with 200ps of pulse-width distortion.
The pulse-width distortion and input current are closely
related (see Typical Operating Characteristics). If the
clock recovery circuit can accept more pulse-width dis-
tortion, a higher input current might be acceptable. For
worst-case responsivity and extinction ratio,
ρ
= 1A/W
and r
e
=
∞
, the input overload is:
Overload (dBm) = -10log (I
max
)(1 / 2)(1000)
For I
max
= 300μA, the MAX3664 overload is -8.2dBm.
Step 2: Selecting Time Constants
A receiver built with the MAX3664 will have a bandpass
frequency response. The low-frequency cutoff causes
unwanted data-dependent jitter and sensitivity loss.
Because SDH/SONET data streams contain scrambled
data, certain data sequences may generate continuous
successions of 1s or 0s. The low-frequency cutoff
forces the output of such sequences to zero, ultimately
causing a sensitivity reduction. The SDH specifications
state that a receiver must be able to handle up to 72
consecutive bits of the same value within the data.
Therefore, choose the low-frequency cutoff to ensure
an acceptable amount of data-dependent jitter and
sensitivity loss.
Determine the reduction in signal-to-noise ratio due to a
transitionless sequence of duration t as follows:
SNR
loss
= 1 - e
-t /
τ
= 1-e
-(2
π
fct)
where
τ
is the time constant of the offset correction, f
c
is the low-frequency cutoff, and t is the time for 72 bits
(116ns for a 622Mbps data rate).
Suppose that the receiver should not have more than
0.25dB (6%) of sensitivity loss due to a 72-bit transition-
less sequence. This means that:
(1 - e
-(2
π
fc)(116ns)
)< 0.06
f
c
= (ln 0.94) / [(-2
π
)(116ns)] = 85kHz (max)
The loss of sensitivity is a concern only when the SNR is
small (close to 12.7), which occurs with input currents
less than 3μAp-p.
622Mbps, Ultra-Low-Power, 3.3V
Transimpedanc e Preamplifier for S DH/S ONET
6
_______________________________________________________________________________________
POWER
TIME
P0
P1
P
AVE
Figure 2. Optical Power Definitions
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MAX3664ESA | Single LVDS Transmitter 5-SOT-23 -40 to 85 |
| MAX3665 | Single LVDS Transmitter 5-SOT-23 -40 to 85 |
| MAX3665EUA | 622Mbps, Ultra-Low-Power, 3.3V Transimpedance Preamplifier for SDH/SONET |
| MAX3667ECJ | +3.3V, 622Mbps SDH/SONET Laser Driver with Automatic Power Control |
| MAX3667 | Single LVDS Transmitter 5-SOT-23 -40 to 85 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX3664E/D | 功能描述:跨阻抗放大器 RoHS:否 制造商:Texas Instruments 封裝 / 箱體:SOIC-14 帶寬:3 MHz 工作電源電壓:36 V 電源電流:5.5 mA 工作溫度范圍:- 40 C to + 85 C 封裝:Tube |
| MAX3664E/D DIE | 制造商:Maxim Integrated Products 功能描述: |
| MAX3664ESA | 功能描述:跨阻抗放大器 RoHS:否 制造商:Texas Instruments 封裝 / 箱體:SOIC-14 帶寬:3 MHz 工作電源電壓:36 V 電源電流:5.5 mA 工作溫度范圍:- 40 C to + 85 C 封裝:Tube |
| MAX3664ESA+ | 功能描述:跨阻抗放大器 RoHS:否 制造商:Texas Instruments 封裝 / 箱體:SOIC-14 帶寬:3 MHz 工作電源電壓:36 V 電源電流:5.5 mA 工作溫度范圍:- 40 C to + 85 C 封裝:Tube |
| MAX3664ESA+T | 功能描述:跨阻抗放大器 RoHS:否 制造商:Texas Instruments 封裝 / 箱體:SOIC-14 帶寬:3 MHz 工作電源電壓:36 V 電源電流:5.5 mA 工作溫度范圍:- 40 C to + 85 C 封裝:Tube |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。