When be systematic power comsumption, ground connection and signal loop to find proper configuration like us, often can introduce a few interference. The “ of the reasonable amplifier that solve IC goes often also be being met when concept of ” of Ou ” , “ ground connection be fooled by the problem place of a few clearly.

 

A run-of-mill principle is elaborated for everybody below, we discuss to go relevantly with integrated circuit amplifier slowly again later Ou and —— of ground connection problem

 

Think please above all: Does electric current flow to where?

 

In light of the surface, this is the problem of a clearly. But when mentioning electric current, people can think of electric current pours out of ” from “ of a certain place commonly, next “ has shed ” other place, ignored electric current however how the issue that regurgitate source selects. In be operated actually, people thinks ” of all “ ground connection or ” of voltage of “ power source are nodded it seems that is equal. But oversight a fact: These dots form voltaic amid to flow and produce finite tension, they are the one part of conductor network.

 

If want program of sex of the look up before undertaking, we must get the starting point that considers electric current and reentry point, must decide the action of the voltage drop that produces as a result. And the principle that this asks to going Ou reachs ground connection circuit again has certain knowledge. Used integrated circuit in the design however when, such information often have no way is gotten with understand hard.

 

Our IC amplifier is one of very commonly used linear IC, but fortunately: With respect to power and ground connection problem character, most operation amplifier but classify minority category. Although the system configures what bring your life Wei possibly to go,Ou reachs signal loop issue, but through understanding operation amplifier, we can be found solve more the basic method of this kind of problem.

 

Operation amplifier has 4 to cite a base

 

After general reader been seeinging the textbook of any an operation amplifier, can meet think: Ideal operation amplifier should have 3 —— that cite a base a pair of inputs that need branch bring foot and an output to cite a base. Following plan institute show:

 

 

Graph 1: 3 end of groovy “ ” operation amplifier

 

But if you have understanding fundamental really, can see a fact be not necessarily so such. If amplifier has an output voltage, then it undertakes metrical with be reference at a certain o’clock necessarily. From the point of ideal operation amplifier, it is had infinite in all the model controls function, what can eliminate an input to bring a foot to serve as reference point consequently is likely. Will look so, return existence to wear the 4th to cite a base necessarily. Change an angle to look, if amplifier needs to provide output electricity to load, criterion this electric current must enter amplifier from a certain place. And in light of good case, input electric current does not flow, come so conclusion remains “ to need the 4th ” that cite a base.

 

A kind of common practice is in the graph middle finger gives the 4th to bring a foot to be carried for ” of “ ground connection. What we don’t discuss is end of ” of “ ground connection, amplifier of operation of most integrated circuit (include a lot of modular operation amplifier) end of ” of ground connection of nonexistent “ . To these circuit, the 4th cites a base is power source brings one of the foot or two. Below this kind of circumstance, people apt puts in voltage of two power source and ground connection ‘s charge together. Road of power supply cord can cry in enlarge really inside bandwidth limits, inferior impedance arises below all frequency. However, when impedance asks to did not get satisfaction, numerous problem is met subsequently and come, include noise, transient state to answer difference, the problem such as oscillation.

 

Poor cent carries changeover to sheet

 

One of main demands of simple operation amplifier are “ input the signal of completely poor cent that carries to load must be changed into Chan Duan to output signal ” . What Chan Duan points to is opposite cite a base at the 4th when often be ignored and of character. This may make the problem complications. Following graphs show 2 times:

 

 

Graph 2: Simplify amplifier of operation of edition “ true ”

 

Plan institute shows signal shedding to be used in a variety of popular integrated circuit series on. Although detail is endless identical, but basic signal method and 101, 741, 748, 777, 4136, 503, 515 wait for amplifier of integrated circuit operation roughly identical. Circuit changes voltage of the input that need branch into the electric current that need branch above all. Function of this input form is in graph 2 in express to be PNP transistor. Pass the voltaic lens that is linked together with course of negative power supply next, become electric current sheet to carry a form from the changeover that need branch. Drive of voltaic mirror output is poor amplifier of a voltage and output class as integrator connective power. This integrator is controlling open loop to answer, its capacitance already but the buy inside adscititious Yi Ke. About above the fact that the specification of this kind of reduced form date has an input that need branch without outstanding integrator mostly. Blast off by a few base extremely voltage is offerred slanting buy, inphase integrator input serves as reference with negaive electricity source.

 

Apparent, the major voltage difference between amplifier output and negative power supply can appear in whole compensation capacitance. If lose power source voltage to produce change suddenly, integrator amplifier will be outputted compulsively subsequently and change. When whole amplifier is in closed circuit to configure, its input the error signal that carries generation to regain depth to output, but restore degree to suffer enlarge of be confined to to cry cry pressure place rate. The result is, this kind of amplifier may have outstanding low frequency power source to control function, but negaive electricity source is restrained put in bigger limitation however. The feedback signal that because bring about what output restores,is flow input end, accordingly, what to frequency output restores is the feedback signal that flow input carries. Accordingly, exceed the signal of closed circuit bandwidth to frequency, negaive electricity source is restrained than will be close to 0. Namely: The communal impedance that circuit of high speed tall n can pass negative power supply cord and ” of communication of “ of low n circuit.

 

Attention: The problem of this kind of amplifier and end of negaive electricity source are relevant. Although positive electricity source is restrained,drop than increasing possibly also because of frequency, but its influence degree is smaller. Generally speaking, the little very short time on positive electricity source changes to be able to be outputted to signal only produce a slight effect. The difference between these sensitivity may make amplifier transient state is answered appear apparent asymmetry phenomenon. If the purpose of drive amplifier is,in its positive electricity of the generation inside rated load limits presses amplitude, criterion amplifier will absorb voltaic pulse from positive electricity source.

 

Such pulse may bring about twinkling of power source power source to change, but positive electricity source restrains what will reduce pair of amplifier to output signal to the greastest extent. Falling with this opposite situation, negative output signal will from inside negaive electricity source draw-out electric current. If pulse brings about “ burr ” on bus line, the negative power supply that owes beautiful restrains function to will output end bring similar “ burr ” in amplifier. Although pulse test can get amplifier transient state is answered, but negative pulse test can aid you to understand power source to lose course transient state to answer better actually, is not amplifier answer!

 

In fact, power source pulse answers itself is not the appears possibly thing on amplifier. 30 or 40 centimeters electrical wiring can act as tall Q power plant, give damp thereby normally exorbitant power source is answered add high frequency part. Around amplifier installation goes Ou capacitance also can not solve a problem certainly, because power source must be in a certain place,go Ou. If go Ou report disgorge is too longer method, still produce undesirable burr likely.

 

The graph is shown 3 times go for negaive electricity source of Ou 3 kinds may be configured. In 3a, the way of negative signal electric current that dotted line represents to open past Ou circuitry and ground connection line. If ” of laden “ ground connection is reached,go ” of Ou “ ground connection connects in power source place, criterion the burr that the burr on ground wire road is similar to bus line of negaive electricity source to go up. The means of ” of “ ground connection according to feedback and signal source, go the ability of design interference rejection that the effective interference that Ou capacitance brings about may be more than capacitance.

 

 

Graph 3a: Source of invalid negaive electricity goes Ou

 

Graph 3b was revealed how to use go the interference that Ou capacitance drops V form and ground connection bus line. The high frequency composition in load current is by limitation in an annulus means that does not contain ground connection method. If the capacity of capacitance is enough big, quality accords with a requirement, the burr that can reduce negaive electricity source to go up and noninterference input or output signal method.

 

 

Graph 3b: Go in the light of what load of ” of “ ground connection optimizes source of Ou negaive electricity

 

If laden case is complex (the 3c) that be like a graph, need to undertake more reflection. If of amplifier drive is the load that flows to fictitious ground, practical load current won’t return ground connection. Contrary, this power source is offerred by the amplifier that forms fictitious ground necessarily.

 

 

Graph 3c: Go in the light of what load of ” of “ fictitious ground optimizes source of Ou negaive electricity

 

Below this kind of circumstance, if go to the negative power supply of the first amplifier,Ou comes the positive electricity source of the 2nd amplifier, can close road of annulus of fast signal electric current and method of noninterference ground connection or signal method. Of course, output fiducial voltage source to avoid to disturb, must offer for the 2nd amplifier come from ground connection the low impedance method of V look bus line. Understanding goes the key of Ou circuit depends on recognize the whereaboutldirection of real load and signal electric current. And the key that optimizes circuit is signal method bypass waits in ground connection these electric current.

 

When considering whole circuit, connect regular meeting occurrence conflict. For example, many amplifier are likely by drive of same power source, and every amplifier needs to go independently again Ou capacitance. Overall and character, go Ou capacitance assumes shunt-wound position entirely. However, in fact, interrelate the power plant of power source and ground connection circuitry can see this kind be like change into an intricate L-C network without the configuration that hinder. Handling fast signal wave blast in the circuit of the face, through counting centimeter of wire cable to go shunt-woundly Ou network means a trouble normally.

 

 

Graph 4: Paralell connection goes Ou syntonic damp

 

Graph 4 revealed the method that will reduce Q of undesirable and syntonic circuit to be worth through little resistance. Usually, these resistor are OK concessional, because they are in,end of operation amplifier power source changes undesirable and high frequency chink into small damp signal. Although odd signal has more low frequency part, but can handle through the power source of operation amplifier controls function and giving.