更改

也就是说，正反馈与输入是同步的，在某种意义上，正反馈增加了输入，使输入变得更大。

也就是说，正反馈与输入是同步的，在某种意义上，正反馈增加了输入，使输入变得更大。

Positive feedback tends to cause system instability. When the loop gain is positive and above 1, there will typically be exponential growth, increasing oscillations, chaotic behavior or other divergences from equilibrium. System parameters will typically accelerate towards extreme values, which may damage or destroy the system, or may end with the system latched into a new stable state. Positive feedback may be controlled by signals in the system being filtered，damped or limited，or it can be cancelled or reduced by adding negative feedback.  

Positive feedback tends to cause system instability. When the loop gain is positive and above 1, there will typically be exponential growth, increasing oscillations, chaotic behavior or other divergences from equilibrium. System parameters will typically accelerate towards extreme values, which may damage or destroy the system, or may end with the system latched into a new stable state. Positive feedback may be controlled by signals in the system being filtered，damped or limited，or it can be cancelled or reduced by adding negative feedback.  

放大器可能会以没有示波器很难检测到的方式轻轻振荡，或者振荡的范围很广，只有一个非常失真或根本不需要的信号通过，或者发生损坏。由于低频寄生振荡与低转速排气音符的声音相似，因此被称为 "汽艇"。

放大器可能会以没有示波器很难检测到的方式轻轻振荡，或者振荡的范围很广，只有一个非常失真或根本不需要的信号通过，或者发生损坏。由于低频寄生振荡与低转速排气音符的声音相似，因此被称为 "汽艇"。

The effect of using a Schmitt trigger (B) instead of a comparator (A)

The effect of using a Schmitt trigger (B) instead of a comparator (A)

使用施密特触发器(b)代替比较器(a)的效果

使用施密特触发器(b)代替比较器(a)的效果

Many common digital electronic circuits employ positive feedback. While normal simple boolean logic gates usually rely simply on gain to push digital signal voltages away from intermediate values to the values that are meant to represent boolean '0' and '1', but many more complex gates use feedback. When an input voltage is expected to vary in an analogue way, but sharp thresholds are required for later digital processing, the Schmitt trigger circuit uses positive feedback to ensure that if the input voltage creeps gently above the threshold, the output is forced smartly and rapidly from one logic state to the other. One of the corollaries of the Schmitt trigger's use of positive feedback is that, should the input voltage move gently down again past the same threshold, the positive feedback will hold the output in the same state with no change. This effect is called hysteresis: the input voltage has to drop past a different, lower threshold to 'un-latch' the output and reset it to its original digital value. By reducing the extent of the positive feedback, the hysteresis-width can be reduced, but it can not entirely be eradicated. The Schmitt trigger is, to some extent, a latching circuit.

Many common digital electronic circuits employ positive feedback. While normal simple boolean logic gates usually rely simply on gain to push digital signal voltages away from intermediate values to the values that are meant to represent boolean '0' and '1', but many more complex gates use feedback. When an input voltage is expected to vary in an analogue way, but sharp thresholds are required for later digital processing, the Schmitt trigger circuit uses positive feedback to ensure that if the input voltage creeps gently above the threshold, the output is forced smartly and rapidly from one logic state to the other. One of the corollaries of the Schmitt trigger's use of positive feedback is that, should the input voltage move gently down again past the same threshold, the positive feedback will hold the output in the same state with no change. This effect is called hysteresis: the input voltage has to drop past a different, lower threshold to 'un-latch' the output and reset it to its original digital value. By reducing the extent of the positive feedback, the hysteresis-width can be reduced, but it can not entirely be eradicated. The Schmitt trigger is, to some extent, a latching circuit.

许多常见的数字电路都采用正反馈。一般简单的布尔逻辑门通常只是依靠增益将数字信号电压从中间值推到代表布尔值0和1的值上，但许多更复杂的门都采用了反馈。当输入电压以模拟方式发生变化，但后期数字处理需要尖锐的阈值时，施密特触发电路使用正反馈，以确保当输入电压轻微超过阈值时，输出被巧妙而迅速地从一个逻辑状态转移到另一个逻辑状态。施密特触发器使用正反馈的一个必然结果是，如果输入电压再次缓慢下降，超过相同的阈值，正反馈将使输出保持在相同的状态而不改变。这种效应被称为滞后: 输入电压必须降到一个不同的、较低的阈值，才能“解锁”输出，并将其重置为原始数字。通过减小正反馈的程度，可以减小滞后宽度，但不能完全消除。施密特触发器在某种程度上是一个闭锁电路。

许多常见的数字电路都采用正反馈。一般简单的布尔逻辑门通常只是依靠增益将数字信号电压从中间值推到代表布尔值0和1的值上，但许多更复杂的门都采用了反馈。当输入电压以模拟方式发生变化，但后期数字处理需要尖锐的阈值时，施密特触发电路使用正反馈，以确保当输入电压轻微超过阈值时，输出被巧妙而迅速地从一个逻辑状态转移到另一个逻辑状态。施密特触发器使用正反馈的一个必然结果是，如果输入电压再次缓慢下降，超过相同的阈值，正反馈将使输出保持在相同的状态而不改变。这种效应被称为滞后: 输入电压必须降到一个不同的、较低的阈值，才能“解锁”输出，并将其重置为原始数字。通过减小正反馈的程度，可以减小滞后宽度，但不能完全消除。施密特触发器在某种程度上是一个闭锁电路。

Positive feedback is a mechanism by which an output is enhanced, such as protein levels. However, in order to avoid any fluctuation in the protein level, the mechanism is inhibited stochastically (I), therefore when the concentration of the activated protein (A) is past the threshold ([I]), the loop mechanism is activated and the concentration of A increases exponentially if d[A]=k [A]

Positive feedback is a mechanism by which an output is enhanced, such as protein levels. However, in order to avoid any fluctuation in the protein level, the mechanism is inhibited stochastically (I), therefore when the concentration of the activated protein (A) is past the threshold ([I]), the loop mechanism is activated and the concentration of A increases exponentially if d[A]=k [A]

正反馈是一种增强输出的机制，如蛋白质水平。但为了避免蛋白质水平的波动，该机制是随机抑制的（I），因此当激活的蛋白质（A）浓度超过阈值（[I]）时，循环机制被激活，如果d[A]=k[A]，A的浓度就会成倍增加。

正反馈是一种增强输出的机制，如蛋白质水平。但为了避免蛋白质水平的波动，该机制是随机抑制的（I），因此当激活的蛋白质（A）浓度超过阈值（[I]）时，循环机制被激活，如果d[A]=k[A]，A的浓度就会成倍增加。

Illustration of an R-S ('reset-set') flip-flop made from two digital nor gates with positive feedback. Red and black mean logical '1' and '0', respectively.

Illustration of an R-S ('reset-set') flip-flop made from two digital nor gates with positive feedback. Red and black mean logical '1' and '0', respectively.

R-S("复位-设置")触发器的说明，由两个带正反馈的数字诺尔门组成。红色和黑色分别表示逻辑上的 "1 "和 "0"。

R-S("复位-设置")触发器的说明，由两个带正反馈的数字诺尔门组成。红色和黑色分别表示逻辑上的 "1 "和 "0"。

An electronic flip-flop, or "latch", or "bistable multivibrator", is a circuit that due to high positive feedback is not stable in a balanced or intermediate state. Such a bistable circuit is the basis of one bit of electronic memory.  The flip-flop uses a pair of amplifiers, transistors, or  logic gates connected to each other so that positive feedback maintains the state of the circuit in one of two unbalanced stable states after the input signal has been removed, until a suitable alternative signal is applied to change the state. Computer random access memory (RAM) can be made in this way, with one latching circuit for each bit of memory.

An electronic flip-flop, or "latch", or "bistable multivibrator", is a circuit that due to high positive feedback is not stable in a balanced or intermediate state. Such a bistable circuit is the basis of one bit of electronic memory.  The flip-flop uses a pair of amplifiers, transistors, or  logic gates connected to each other so that positive feedback maintains the state of the circuit in one of two unbalanced stable states after the input signal has been removed, until a suitable alternative signal is applied to change the state. Computer random access memory (RAM) can be made in this way, with one latching circuit for each bit of memory.