Amfutar da kudin karamin sauti ko Amfutar da kudin aiki
An amfutar da hanyar aiki ko op amp shine amfutar da hanyar aiki na tsohon kofin tsari da zafi mai yawa a gajiya.
Op amp yana iya cewa shine amfutar da hanyar aiki na mafi girma da ake haɗa daga baya-bayan amfutar da hanyar aiki a matsayin hanyoyi. A kan aikinsa akwai kungiyoyi, FETs da kungiyoyi. Duk da cewa ana iya yaɗa a wurin kadan, saboda haka ana samun shi a matsayin ci gaba da yake da shi a Integrated Circuit (IC) form. Sunan Op Amp ana amfani da ita don nuna amfutar da hanyar aiki wanda ake iya haɗa suka yi ayyuka masu aiki kamar hanyoyi, rarrabe, karama, ido, jami'a, da sauransu. Misalidansa shine IC 741.
Alama ta da kyau a matsayin IC ta shahara a nan. Alaman yana nuna cewa asali yaɗa a matsayin siffofin da ke nuna cewa asalin yaɗa a matsayin siffon.
Matsayin Da Kuma Asalin Amfutar da Hanyar Aiki
Amfutar da hanyar aiki yana da matsayin biyu da asalin kasa. Amfutar da hanyar aiki na iya kula da matsayin biyar da kuma asalin kasa. Matsayin biyar suna nuna alamar da ke nuna cewa asali yaɗa a matsayin siffon. Ana kiran matsayin da aka fi siffon minus (-) a matsayin matsayin inverting da kuma matsayin da aka fi siffon plus (+) a matsayin non-inverting terminal. Idan ake bayar asalin siffon a matsayin inverting (-) yana iya haɗa aiki a matsayin 180o out of phase concerning the applied input signal. Idan ake bayar asalin siffon a non-inverting terminal (+) yana iya haɗa aiki a matsayin in phase, i.e. it will have no phase shift concerning the input signal.
Kulan Tsari don Amfutar da Hanyar Aiki
Kamar yadda ake nuna a matsayin circuit symbol, akwai matsayin biyar da kula da kulan tsari +VCC da –VCC. Don aiki a amfutar da hanyar aiki, an buƙaci da dual polarity DC supply. A dual polarity supply, ake kula da +VCC zuwa positive DC supply da –VCC terminal zuwa negative DC supply. Amma wasu amfutar da hanyar aiki suna iya aiki a single polarity supply. Note that there is no common ground terminal in the op-amps hence the ground has to be established externally.
Tsarin Aiki na Op-Amp
Aiki na Open Loop na Amfutar da Hanyar Aiki
Kamar yadda ake cewa, amfutar da hanyar aiki yana da differential input da single ended output. Saboda haka, idan ake bayar asalin biyar, waɗannan biyar suna iya haɗa aiki a matsayin difference between the two applied input signals. We call this difference between two input signals as the differential input voltage. The equation below gives the output of an operational amplifier.
Where, VOUT is the voltage at the output terminal of the op-amp. AOL is the open-loop gain for the given op-amp and is constant (ideally). For the IC 741 AOL is 2 x 105.
V1 is the voltage at the non-inverting terminal.
V2 is the voltage at the inverting terminal.
(V1 – V2) is the differential input voltage.
It is clear from the above equation that the output will be non-zero if and only if the differential input voltage is non-zero (V1 and V2 are not equal), and will be zero if both V1 and V2 are equal. Note that this is an ideal condition, practically there are small imbalances in the op-amp. The open-loop gain of an op-amp is very high. Hence, an open loop operational amplifier amplifies a small applied differential input voltage to a huge value.
Also, it is true that if we apply small differential input voltage, the operational amplifier amplifies it to a considerable value but this significant value at the output cannot go beyond the supply voltage of the op-amp. Hence it does not violate the law of conservation of energy.
Closed Loop Operation
The above-explained operation of the op-amp was for open-loop i.e. without a feedback. We introduce feedback in the closed loop configuration. This feedback path feeds the output signal to the input. Hence, at the inputs, two signals are simultaneously present. One of them is the original applied signal, and the other is the feedback signal. The equation below shows the output of a closed loop op-amp.
Where VOUT is the voltage at the output terminal of the op-amp. ACL is the closed loop gain. The feedback circuit connected to the op-amp determines the closed loop gain ACL. VD = (V1 – V2) is the differential input voltage. We say the feedback as positive if the feedback path feeds the signal from the output terminal back to the non-inverting (+) terminal. Positive feedback is used in oscillators. The feedback is negative if the feedback path feeds the part of the signal from the output terminal back to the inverting (-) terminal. We use negative feedback to the op-amps used as amplifiers. Each type of feedback, negative or positive has its advantages and disadvantages.
Positive Feedback ⇒ Oscillator
Negative Feedback ⇒ Amplifier
Th above explanation is the most basic working principle of operational amplifiers.
Ideal Op-Amp Characteristics
An ideal op-amp should have the following characteristics:
Infinite voltage gain (So that maximum output is obtained)
Infinite input resistance (Due to this almost any source can drive it)
Zero output resistance (So that there is no change in output due to change in load
