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參數資料
| 型號： | LMH6622 |
| 廠商： | National Semiconductor Corporation |
| 元件分類： | 運算放大器 |
| 英文描述： | Dual Wideband, Low Noise, 160MHz, Operational Amplifiers |
| 中文描述： | 雙寬帶，低噪聲，頻率高達160MHz，運算放大器 |
| 文件頁數： | 14/18頁 |
| 文件大小： | 540K |
| 代理商： | LMH6622 |
DSL Receive Channel Applications
(Continued)
The two R
resistors are used to provide impedance match-
ing through the 1:N transformer.
Where R
L
is the impedance of the twisted pair line.
N is the turns ratio of the transformer.
The resistors R
and R
are used to set the receive gain of
the pre-amp. The receive gain is selected to meet the ADC
full-scale requirement of a DSL chipset.
Resistor R
and R
along with R
are used to achieve
cancellation of the output driver signal at the output of the
receiver.
Since the LMH6622 is configured as an inverting summing
amplifier, V
OUT
is found to be,
The expression for V
1
and V
2
can be found by using super-
position principle.
When V
S
= 0,
When V
A
= 0,
Therefore,
And then,
Setting R
= 2*R
to cancel unwanted driver signal in the
receive path, then we have
We can also find that,
And then
In conclusion, the peak-to-peak voltage to the ADC would
be,
Receive Channel Noise Calculation
The circuit of Figure 2 also has the characteristic that it
cancels noise power from the drive channel.
The noise gain of the receive pre-amp is found to be:
Noise power at each of the output of LMH6622:
where
V
n
i
n
i
non-inv
i
inv
k
T
R
+
Input referred voltage noise
Input referred current noise
Input referred non-inverting current noise
Input referred inverting current noise
Boltzmann’s constant, K = 1.38 x 10
23
Resistor temperature in k
Source resistance at the non-inverting input
to balance offset voltage, typically very small
for this inverting summing applications
For a voltage feedback amplifier,
Therefore, total output noise from the differential pre-amp is:
The factor ’2 ’ appears here because of differential output.
Differential Analog-to-Digital Driver
20029239
FIGURE 3. Circuit for Differential A/D Driver
L
www.national.com
14
相關PDF資料 |
PDF描述 |
|---|---|
| LMH6622MA | Dual Wideband, Low Noise, 160MHz, Operational Amplifiers |
| LMH6622MAX | Dual Wideband, Low Noise, 160MHz, Operational Amplifiers |
| LMH6622MM | Dual Wideband, Low Noise, 160MHz, Operational Amplifiers |
| LMH6622MMX | Dual Wideband, Low Noise, 160MHz, Operational Amplifiers |
| LMH6624 | Single/Dual Ultra Low Noise Wideband Operational Amplifier |
相關代理商/技術參數 |
參數描述 |
|---|---|
| LMH6622MA | 功能描述:運算放大器 - 運放 RoHS:否 制造商:STMicroelectronics 通道數量:4 共模抑制比（最小值）:63 dB 輸入補償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風格:SMD/SMT 封裝 / 箱體:QFN-16 轉換速度:0.89 V/us 關閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel |
| LMH6622MA/NOPB | 功能描述:運算放大器 - 運放 Low Noise Dual Amp RoHS:否 制造商:STMicroelectronics 通道數量:4 共模抑制比（最小值）:63 dB 輸入補償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風格:SMD/SMT 封裝 / 箱體:QFN-16 轉換速度:0.89 V/us 關閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel |
| LMH6622MAX | 功能描述:運算放大器 - 運放 RoHS:否 制造商:STMicroelectronics 通道數量:4 共模抑制比（最小值）:63 dB 輸入補償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風格:SMD/SMT 封裝 / 箱體:QFN-16 轉換速度:0.89 V/us 關閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel |
| LMH6622MAX/NOPB | 功能描述:運算放大器 - 運放 RoHS:否 制造商:STMicroelectronics 通道數量:4 共模抑制比（最小值）:63 dB 輸入補償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風格:SMD/SMT 封裝 / 箱體:QFN-16 轉換速度:0.89 V/us 關閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel |
| LMH6622MM | 功能描述:運算放大器 - 運放 RoHS:否 制造商:STMicroelectronics 通道數量:4 共模抑制比（最小值）:63 dB 輸入補償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風格:SMD/SMT 封裝 / 箱體:QFN-16 轉換速度:0.89 V/us 關閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel |
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