Graph 1 carry discharge presses follow circuit

 

Voltage follow circuit is analysed

 

If our join carries put output turns over photograph input end to it, bring to bear on in inphase input end next signal of a voltage, the follow with the output can very good voltage that we can discover to carry is put is worn input voltage.

 

Assume initiative condition carries voltage of put input, output is 0V, when beginning to increase from 0V when Vin next, vout also can increase, and it is toward positive electricity the direction that control increases. Because assume Vin increases suddenly,this is, vout has not been answered still is 0V when, ve=Vin-Vout is to be more than of 0, multiply so on the open loop gain that carry puts, vout=Ve*A, make the direction that carries put output Vout begins to be pressed toward positive electricity increases.

 

When increasing as Vout, output voltage is returned to turn over photograph input end by feedback, can reduce carry to put two inputs next between end press difference, namely Ve can be reduced, below the circumstance of similar open loop gain, vout nature can be reduced. Final result is, no matter the input is how old input voltage (it is to be inside the input voltage range that carry puts of course) , carry puts the voltage that can output to be close to Vin very from beginning to end, but Vout of this output voltage is just under Vin, put two inputs with assuring use there is enough voltage to differ Ve between end, will maintain the output that carry puts, namely Vout=Ve*A.

 

Carry puts the negative feedback in circuit

 

This circuit can reach a steady state very quickly, the amplitude that outputs voltage will be very accurate maintain carry to put two inputs between end press difference, this Ve that press difference can produce accurate carry to put the amplitude that outputs voltage conversely. Turn over those who carry put output and carry are put photograph input to carry join, such means is called to lose feedback, this is to make the system achieves the key that stabilizes oneself. This applies to carry to put not just, apply to any common dynamic systems likewise. This kind of stability makes carry is put have the job the ability of online sex mode, is not the condition that is in saturation merely, complete “ opens ” complete perhaps “ closes ” , the comparator that is used at doing not have any negative feedback like it is same.

 

The gain that puts as a result of carry is very tall, the voltage that inputs Duan Wei to hold instead is put in carry almost as equal as Vin. E.g. , the open loop gain that a carry puts is 200 000. If Vin is equal to 6V, outputting voltage at this moment can be 5.999 970 000 149 999V. This is carrying put input end produced enough voltage to differ Ve=6V-5.999 970 000 149 999V=29.999 85uV, this voltage can is in to output end to produce amplitude to be the voltage of 5.999 970 000 149 999V next by enlarge, thereby this system will be stable here. What you see no less than, 29.999 85uV is a very little tension, accordingly to actual computation, the carry that we can think to be maintained by negative feedback puts two inputs to carry the Ve=0V pressing difference between, whole process is shown 2 times like the graph. This namely our familiar “ empty short ” , and because carry two put inputs carry the impedance between,be very big, also had “ empty naturally to break ” . The circuit below has the stable closed circuit gain of 1 times, the follow with output can simple voltage inputs voltage.

 

Graph the action of 2 negative feedback

 

A when use negative feedback very large dominant position is, we need not care the actual voltage gain that carry puts, as long as it is enough big OK. If carry put voltage gain is not 200 0000 however 250 000, this meeting makes the output voltage that carry puts can more adjacent Vin a few, the voltage difference between smaller input end uses the output tension that produces need. In the graph in the circuit of 2 signal, output voltage can be equal to carry to put the input voltage that inputs end to go up instead likewise. Accordingly, to circuit design engineer, to realize the stable closed circuit gain of enlarge circuit, carrying put open loop gain was not necessary is an exact value, negative feedback can make systematic ego is adjusted.

 

Use negative feedback to be able to improve the precision of impedance of stability of degree of linearity, gain, output, gain, but use negative feedback to also can bring a serious problem likewise, that reduces systematic stability namely, and for the voltage follow circuit to unit gain, this is a kind of worst circumstance, below the condition that contains sexual load in drive especially, interested classmate is OK oneself go consulting relevant data.

 

Put circuit about carry, a lot of moment we are engrafted to turn over photograph end follow is carried in phase, resemble in front what say in that way, cannot carry follow instead in phase?

 

To the voltage follow circuit that tells today, can be to turn over photograph end to chase after be accompanying to be carried only. Because if be being carried instead,here brings to bear on one input voltage, receive output inphase end repeatedly, same hypothesis output is 0, that Ve can be a negative voltage, take the open loop gain that puts with carry, that output can be a negative voltage, return the inphase input that puts to carry to carry, can get the negaive electricity with an absolutely big watch presses difference further. Carry put output can reach saturation very quickly, nature also cannot come true to carry follow to turn over photograph end in phase.

 

But put to carry for, if be being carried instead,bring to bear on referenced voltage, cooperate other electron yuan parts of an apparatus, wait like dynatron, MOS, make the integral annulus way that carry puts forms negative feedback, also can make carry follow to turn over photograph end in phase likewise, and the carries follow in phase instead law that the motion that this broke us naturally also to be familiar with puts.

 

The voltage follow circuit that carry puts, empty of ” empty short ” , “ breaks ” is the surface, and negative feedback just is a root. Be based on this root, can help us very well understand Protean carry discharge way.