First of all, the circuit board factory will first learn the basic points of the negative feedback amplifier circuit with you.
What is positive feedback? The feedback signal of the positive feedback is in the same phase as our input signal. When adding, it is actually very easy for oscillation to appear at this time.What is negative feedback? Negative feedback is to ensure that our amplifier circuit can work normally in our operating range. The meaning of mining is that the feedback signal and the input signal of our amplifier circuit are in opposite phase and do subtraction.
After talking about this, let's return to our topic. Let's take a look at what voltage feedback is.
HDI PCB with Black solder mask
Voltage feedback judgment: The output signal is cancelled, the feedback has no signal, whether the sampling point and the output terminal are at a point, if it is a point, it belongs to the voltage feedback, and the output terminal of the parallel circuit.
How to understand that the voltage feedback output resistance is small: it is beneficial for the parallel voltage to be equal everywhere, and the parallel resistance becomes smaller to understand.PCB factory summary:
The sampling element of voltage feedback is the parallel output terminal, and the output resistance is small.
We see that the output terminal is fed back in parallel; it is concluded that it is voltage feedback, and the output signal is cancelled at the same time, and there is no signal in the feedback.After reading what is voltage feedback, let's take a look at current feedback.
Current feedback: It is the current collection of the signal at the output of our amplifier. We know that the current of the series resistance is equal everywhere, and the series resistance is equal to the sum of each resistance. We can borrow this to understand that current feedback is that the feedback element is connected in series. The output of our feedback. Increase the resistance of the output resistor. At the same time, the feedback sampling signal is not at the same end as our output.Look at the picture: Let's take a look at this, R is our load resistance.
Let's take a look at the circuit board factory and everyone. The sampling point of the RF and the output end are different. They are connected in series with the sampling output resistance. When the output signal is cancelled, there is also a signal (see the endpoint is a negative signal).
Circuit board factory summary: voltage and current feedback look at the output of the amplifier, voltage feedback reduces the output resistance, and current feedback increases the output resistance.Voltage feedback can stabilize the output voltage, reduce the output resistance, and improve the ability to drive the load.
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