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参数资料
| 型号： | MAX3664ESA |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 9/12页 |
| 文件大小： | 0K |
| 描述： | IC PREAMP 622MBPS TRANS 8-SOIC |
| 标准包装： | 100 |
| 类型： | 转阻前置放大器 |
| 应用： | 光纤学网络 |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 供应商设备封装： | 8-SOIC |
| 包装： | 管件 |
MAX3664
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, in, (bandwidth-
limited to 470MHz) is 55nARMS. 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[(in /
ρ)(SNR)(1/2)(re + 1) / (re - 1)(1000)]
At room temperature, with re = 10, SNR = 12.7, in =
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
(Imax) is 300Ap-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 re =
∞, the input overload is:
Overload (dBm) = -10log (Imax)(1 / 2)(1000)
For Imax = 300A, 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:
SNRloss = 1 - e-t /
τ = 1-e-(2πfct)
where
τ is the time constant of the offset correction, fc
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-(2πfc)(116ns)) < 0.06
fc = (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 3Ap-p.
622Mbps, Ultra-Low-Power, 3.3V
Transimpedance Preamplifier for SDH/SONET
6
_______________________________________________________________________________________
POWER
TIME
P0
P1
PAVE
Figure 2. Optical Power Definitions
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX3664ESA+ | 功能描述:跨阻抗放大器 RoHS:否 制造商:Texas Instruments 封装 / 箱体:SOIC-14 带宽:3 MHz 工作电源电压:36 V 电源电流:5.5 mA 工作温度范围:- 40 C to + 85 C 封装:Tube |
| MAX3664ESA+T | 功能描述:跨阻抗放大器 RoHS:否 制造商:Texas Instruments 封装 / 箱体:SOIC-14 带宽:3 MHz 工作电源电压:36 V 电源电流:5.5 mA 工作温度范围:- 40 C to + 85 C 封装:Tube |
| MAX3664ESA-T | 功能描述:跨阻抗放大器 RoHS:否 制造商:Texas Instruments 封装 / 箱体:SOIC-14 带宽:3 MHz 工作电源电压:36 V 电源电流:5.5 mA 工作温度范围:- 40 C to + 85 C 封装:Tube |
| MAX3664EUA | 功能描述:特殊用途放大器 RoHS:否 制造商:Texas Instruments 通道数量:Single 共模抑制比（最小值）: 输入补偿电压: 工作电源电压:3 V to 5.5 V 电源电流:5 mA 最大功率耗散: 最大工作温度:+ 70 C 最小工作温度:- 40 C 安装风格:SMD/SMT 封装 / 箱体:QFN-20 封装:Reel |
| MAX3664EUA+T | 功能描述:特殊用途放大器 RoHS:否 制造商:Texas Instruments 通道数量:Single 共模抑制比（最小值）: 输入补偿电压: 工作电源电压:3 V to 5.5 V 电源电流:5 mA 最大功率耗散: 最大工作温度:+ 70 C 最小工作温度:- 40 C 安装风格:SMD/SMT 封装 / 箱体:QFN-20 封装:Reel |
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