CN1505262A - A Method for Adjusting the Threshold Voltage in a Limiting Amplifier - Google Patents
A Method for Adjusting the Threshold Voltage in a Limiting Amplifier Download PDFInfo
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- CN1505262A CN1505262A CNA021523894A CN02152389A CN1505262A CN 1505262 A CN1505262 A CN 1505262A CN A021523894 A CNA021523894 A CN A021523894A CN 02152389 A CN02152389 A CN 02152389A CN 1505262 A CN1505262 A CN 1505262A
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Abstract
本发明公开了一种限幅放大器中阈值电压调整方法，输入信号经交流耦合后进入限幅放大器的一端，并在此端加入固定的偏置电压，使其有确定的工作点，另一端输入阈值电压，进行差分限幅放大，所述阈值电压由固定阈值电压和可调阈值电压两部分相叠加形成，所述可调阈值电压根据输入信号的幅值形成。由于根据接收信号幅值的大小和噪声产生的机理精确的设置限幅放大器的阈值电压，可获得更高的接收灵敏度；同时，此阈值电压可以根据实际情况进行远程调整，提高了系统的灵活性和可操作性。
The invention discloses a threshold voltage adjustment method in a limiting amplifier. The input signal enters one end of the limiting amplifier after AC coupling, and a fixed bias voltage is added to this end to make it have a definite working point, and the other end inputs The threshold voltage is used for differential limiting amplification. The threshold voltage is formed by superimposing a fixed threshold voltage and an adjustable threshold voltage. The adjustable threshold voltage is formed according to the amplitude of the input signal. Because the threshold voltage of the limiting amplifier is accurately set according to the amplitude of the received signal and the mechanism of noise generation, higher receiving sensitivity can be obtained; at the same time, the threshold voltage can be adjusted remotely according to the actual situation, which improves the flexibility of the system and operability.
Description
Technical field
The present invention relates to method for adjusting voltage threshold in a kind of limiting amplifier.
Background technology
In the environment of optical-fiber network, the opto-electronic conversion that receiving unit is main and the prime of signal are amplified, the processing of back level amplitude limit amplification and back level, as shown in Figure 1, the signal that receives is mostly through the transmission of long distance and multistage light amplification, has very poor signal to noise ratio, because chromatic dispersion and the distorted signals that also can make such as non-linear, the processing of received signal seems more crucial like this, utilizing amplitude limit to amplify and adjusting to the received signal is exactly a kind of effective method, the operation principle that amplitude limit amplifies is to carry out linear amplification when the amplitude of input signal less than the signal of certain value, carry out non-linear amplification greater than this value, the amplitude of signal is amplified to the amplitude of logic level, be to be reference point during amplification with the threshold voltage, positive and negative amplitude limit respectively is amplified to " 1 ", " 0 " logic level, threshold voltage point is particularly important accurately therefore to find limiting amplifier according to the signal that receives.
In addition, the signal that receives after long Distance Transmission, often distorts mostly, and top a lot of noises that superposeed, and need amplify its amplitude limit just to enter subordinate's processing.Now illustrate in conjunction with Fig. 2 a, when threshold voltage is in " 1 ", the centre of " 0 " logic level, during Vc position among the figure, no matter The noise, both sides are that the benchmark amplitude limit amplifies with voltage V1, V2 respectively, be that above " 1 " signal limiter of V1 is amplified to LEVEL1, following " 0 " signal limiter of V2 is amplified to LEVEL2, and to be the position of Vc have identical pressure reduction in the crosspoint of LEVEL1 and LEVEL2 distance map 2b, so just changes the standard signal shown in Fig. 2 b into.In fact the threshold voltage that is provided with like this is not the best, because be superimposed upon " 1 ", noise on " 0 " logic level is also uneven, especially a lot of noises has superposeed above the small-signal after long Distance Transmission, threshold voltage in the middle of being located at easily causes error code, reduce receiving sensitivity greatly, and its threshold value is non-adjustable, lacks flexibility.
Summary of the invention
The invention provides method for adjusting voltage threshold in a kind of limiting amplifier, the mechanism that produces according to the size of received signal amplitude and noise is provided with the threshold voltage of limiting amplifier accurately, obtains higher receiving sensitivity with this.
For achieving the above object, technical scheme of the present invention specifically is achieved in that
Method for adjusting voltage threshold in a kind of limiting amplifier, it is characterized in that: input signal enters an end of limiting amplifier after AC coupled, and at the fixing bias voltage of this end adding, make it that definite working point be arranged, other end input threshold voltage, carry out the difference amplitude limit and amplify, described threshold voltage is by fixed threshold voltage and superimposed formation of adjustable threshold voltage two parts.
Described fixed threshold voltage is arranged on " 1 ", the voltage of the centre of " 0 " logic level, and its value equals fixed bias voltage and input signal mean value sum.
Described adjustable threshold voltage forms according to the amplitude of input signal, amplitude detect output voltage V+, V-, the amplitude size of described V+ reflected input signal, V-is the reference voltage that amplitude detects, the difference of V+, V-is amplified after analog-to-digital conversion A/D input central processing unit CPU, CPU forms adjustable threshold voltage after the data of gathering are handled behind digital-to-analogue conversion D/A.
Described threshold voltage is adjusted up and down at fixed threshold voltage Vc, until reaching the minimum error rate.
According to the effect of received signal, can carry out computing by the data of network remote Controlled CPU after to the A/D conversion, finish real-time threshold voltage adjustment.
Compared with prior art,, reduce the error rate greatly, improve and accept sensitivity, improve system tolerance according to the size of input signal threshold voltage adjustments to limiting amplifier.Simultaneously, this threshold voltage can carry out long-range adjustment according to actual conditions, has improved the flexibility and the operability of system, and this circuit adopts CPU control, and its control has maximum flexibility, also can control by network remote, is fit to the management of networking.
Description of drawings
Fig. 1 is the theory diagram of optical transmission system receiving unit;
Fig. 2 is limiting amplifier work principle figure;
Fig. 3 is the noise pattern of light signal;
Fig. 4 is the specific implementation block diagram that threshold voltage of the present invention is adjusted.
Embodiment
Elaborate realization principle of the present invention and technical scheme below in conjunction with embodiment and accompanying drawing.
Light signal is through multistage light amplification during reception, has very poor signal to noise ratio, and the spontaneous radiation that is exaggerated (Amplified Spontaneous Emission is called for short ASE) noise causes the noise imbalance, increase through Erbium-Doped Fiber Amplifier EDFA (Erbium Doped Fiber Amplifier) back ASE noise, the noise of noise superimposed on the level "0" on the level"1" after often amplifying, as shown in Figure 3, if threshold value is arranged on the Vc position of Fig. 3, then the signal to noise ratio of " 1 " is well below the signal to noise ratio of " 0 ", in order to obtain the best error rate, the setting of threshold value should be away from noise, the point that the signal to noise ratio of " 1 " is suitable with the signal to noise ratio of " 0 " is only optimum point, as the Vb position of Fig. 3.But the signal that receives also can reason such as be inserted or insert down because of going up of the deterioration in aging, the optical fiber of light source, passage and change in time, and it is also undesirable to set the threshold value of fixing like this, will increase the error rate.Especially when optical channel transmission be when making zero RZ (Return Zero) sign indicating number, the more multistage EDFA of this signal process, Signal Degrade more serious has worse signal to noise ratio, the adjustment of threshold value seems even more important.
In the practical operation, need make its fluctuation accurately up and down, reach the minimum error rate, elaborate the principle of specific implementation of the present invention below with this according to the big or small real-time adjustment threshold value of input signal at the Vc of Fig. 3.Theory diagram of the present invention is as shown in Figure 4: signal is with single-ended form input, after AC coupled, enter limiting amplifier, and add a fixing bias voltage at this end, make it that definite working point be arranged, signal interacted before and after AC coupled can be isolated, mainly be the input of isolating direct current signal in the fixed bias voltage, other end input threshold voltage carries out the difference amplitude limit and amplifies.Threshold voltage comprises two parts: fixed threshold voltage Vc and variable adjustment threshold voltage.Fixed threshold voltage is arranged on " 1 ", the voltage of the centre of " 0 " logic level, and its value equals fixed bias voltage and input signal mean value sum.
In fact, what we paid close attention to is not this voltage, but the adjustable threshold voltage behind the D/A (digital-to-analogue conversion).Adjustable threshold voltage forms according to the amplitude of input signal.Amplitude detection output voltage V+, V-, the amplitude size of V+ reflected input signal, V-is the reference voltage that amplitude detects, the difference of the two is directly proportional with the amplitude of input signal, difference is amplified after A/D (analog-to-digital conversion) input CPU (CPU), so promptly finish the collection of data, the situation at that time of the data reflected signal of this collection, as whether changing, information such as the size of signal, therefore next the adjustment of threshold voltage is just evidence-based, to the data of gathering by after certain algorithm calculation process, form after the D/A conversion and adjust threshold voltage, this voltage is superimposed upon and forms the threshold voltage that we wish on the fixed threshold voltage, and threshold voltage can be adjusted arbitrarily up and down at fixed threshold voltage Vc, can be arranged on " 1 " accurately, 40%, 30% or the like of " 0 " logic level is until reaching the minimum error rate.In addition, utilization CPU control has maximum flexibility, and can be real-time, any accurate adjusting also can be controlled by network remote, are fit to network management.
Claims (5)
1, method for adjusting voltage threshold in a kind of limiting amplifier, it is characterized in that: input signal enters an end of limiting amplifier after AC coupled, and at the fixing bias voltage of this end adding, make it that definite working point be arranged, other end input threshold voltage, carry out the difference amplitude limit and amplify, described threshold voltage is by fixed threshold voltage and superimposed formation of adjustable threshold voltage two parts.
2, method for adjusting voltage threshold in the limiting amplifier according to claim 1, it is characterized in that: described fixed threshold voltage is arranged on " 1 ", the voltage of the centre of " 0 " logic level, its value equal fixed bias voltage and input signal mean value sum.
3, method for adjusting voltage threshold in the limiting amplifier according to claim 1, it is characterized in that: described adjustable threshold voltage forms according to the amplitude of input signal, amplitude detect output voltage V+, V-, the amplitude size of described V+ reflected input signal, V-is the reference voltage that amplitude detects, the difference of V+, V-is amplified after analog-to-digital conversion A/D imports central processing unit CPU, and CPU forms adjustable threshold voltage after the data of gathering are handled behind digital-to-analogue conversion D/A.
4, method for adjusting voltage threshold in the limiting amplifier according to claim 1 is characterized in that: described threshold voltage is adjusted up and down at fixed threshold voltage Vc, until reaching the minimum error rate.
5, method for adjusting voltage threshold in the limiting amplifier according to claim 3 is characterized in that: according to the effect of received signal, carry out computing by the data of network remote Controlled CPU after to the A/D conversion, finish real-time threshold voltage adjustment.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 02152389 CN1235335C (en) | 2002-12-04 | 2002-12-04 | A threshold value voltage adjustment method in limiting amplifier |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 02152389 CN1235335C (en) | 2002-12-04 | 2002-12-04 | A threshold value voltage adjustment method in limiting amplifier |
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| CN1505262A true CN1505262A (en) | 2004-06-16 |
| CN1235335C CN1235335C (en) | 2006-01-04 |
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| CN 02152389 Expired - Fee Related CN1235335C (en) | 2002-12-04 | 2002-12-04 | A threshold value voltage adjustment method in limiting amplifier |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100438354C (en) * | 2003-03-18 | 2008-11-26 | 华为技术有限公司 | Automatic pulse with regulating method and device |
| CN101102160B (en) * | 2007-06-13 | 2010-06-09 | 华为技术有限公司 | Threshold voltage adjustment unit, adjustment method, limiting amplifier and optical receiver |
| CN101350675B (en) * | 2008-09-10 | 2012-05-02 | 烽火通信科技股份有限公司 | Threshold detection circuitry for limiting amplifier |
| CN113517866A (en) * | 2021-07-07 | 2021-10-19 | 广州市迪士普音响科技有限公司 | Operational amplifier and feedback type amplitude limiting circuit of operational amplifier |
-
2002
- 2002-12-04 CN CN 02152389 patent/CN1235335C/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100438354C (en) * | 2003-03-18 | 2008-11-26 | 华为技术有限公司 | Automatic pulse with regulating method and device |
| CN101102160B (en) * | 2007-06-13 | 2010-06-09 | 华为技术有限公司 | Threshold voltage adjustment unit, adjustment method, limiting amplifier and optical receiver |
| CN101350675B (en) * | 2008-09-10 | 2012-05-02 | 烽火通信科技股份有限公司 | Threshold detection circuitry for limiting amplifier |
| CN113517866A (en) * | 2021-07-07 | 2021-10-19 | 广州市迪士普音响科技有限公司 | Operational amplifier and feedback type amplitude limiting circuit of operational amplifier |
| CN113517866B (en) * | 2021-07-07 | 2024-02-13 | 广州市迪士普音响科技有限公司 | Operational amplifier and feedback type amplitude limiting circuit thereof |
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| Publication number | Publication date |
|---|---|
| CN1235335C (en) | 2006-01-04 |
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