Description of conservation of amplifier energy

Summary

In a amplifying circuit, all components require the provision of energy, and the realization of this function is "Source ". In the course of work, the energy conversion methods mainly involve loss and storage, but the energy conservation law is followed throughout the process.

Keywords:

Energy Conversion conservation loss storage
We often hear people ask: "When amplifying a circuit, we always feel that after amplification, the energy will not be retained? Or does the current and voltage increase? How can the energy be conservation ?" First of all, here we propose a concept-electrical signal, which refers to the electronic signal. The amplifying circuit is an electrical signal, and we always use current and voltage to describe a circuit for simplicity and convenience, when it comes to the nature of the circuit, it cannot be resolved by the current and voltage.

In the amplifier circuit, the amplifier circuit consists of the amplifier, DC source and offset circuit, input circuit and output circuit. An amplifier is the core of a amplifier circuit. It generally refers to a transistor or its combination. They follow different principles to create components that are amplified by current, voltage, and power. According to our knowledge, if there is a circuit with a power magnification of 100 and the input power is set to 1 W, the output power is 100 W, we will get used to the idea that w = PT, at the same time, the output energy is 100 times the input energy, resulting in the idea of conservation of energy. But we know the DC power supply in the amplifier circuit, and it is the power that provides this 99 w * t, the energy is from the power supply, not out of nothing, specifically, the circuit has a bias voltage VCC, and the current gain energy is from the offset power supply. The energy of the DC source and the input source provides energy for the entire circuit. The energy of the input source provides the input resistance, and the rest is the input port energy of the entire amplification circuit, that is, the input source does not provide energy for the output end. Therefore, no matter how amplified your circuit is, the energy gain will not exceed the energy provided by the DC power supply. There is an energy loss between the transistor itself and the resistor (excluding the input resistor). Here the resistor converts the energy, and most of the energy is used for work, it is inevitable that a small part of the radiation and electromagnetic radiation are emitted to the outside world. Therefore, within the range permitted by the error, the entire circuit complies with the conservation of energy.

That's why we have the illusion that the root cause is "control". In other words, we can control large currents with small currents through amplifiers. Let's take a simple example: When we were a child, we threw it out, and the energy at that moment was much greater than the energy we consumed when we threw it, can we say this violates the conservation of energy? --- No, the instantaneous huge energy is also provided by the chemical composition of the firecrackers and the energy of vigorous movements of air molecules, but this energy can be controlled. This phenomenon is essentially in line with the conservation of energy. From professional knowledge, the process of transistor amplification actually refers to the process of small signals controlling large signals. Instead of generating large signals with small signals alone. So to some extent, we can say that the conservation of power in the amplifying circuit is the conservation of energy in the transistor.

There are many ways to realize the energy conversion in the amplifier circuit. The most common is the Resistance Loss Energy (Self loss, heat radiation and electromagnetic radiation), and the capacitor inductance stores energy. Both consumption and storage power are actually energy conversion. However, the energy consumed by the resistor is irreversible, and the energy stored by the capacitor inductor is reversible. Sometimes the energy stored by the capacitor inductor is provided to the resistor, but sometimes they are transformed from the circuit prototype, at this time, their role is not to store energy, but to consume energy, which is irreversible, so they can be seen as resistance with a certain resistance. It can be seen that there are a variety of energy conversion methods in the circuit, and the main body of the conversion energy is closely related.

In a amplifying circuit, if a steady output voltage is obtained, the circuit introduces a diode to stabilize the voltage. The diode is connected at both ends of the resistor. When the current flowing through the resistor changes, the voltage at both ends is kept at around 0.7v. This is the principle of the diode. There is a problem here: when the input signal provides a voltage of 10 V for the two ends of the resistance and the diode works, the voltage is only 0.7 V. Where is the remaining 9.3v? Does the circuit not follow conservation of energy after the Steady-amplitude diode is introduced? However, this is not the case. When the voltage at both ends of the diode does not reach the diode conduction pressure drop (about 0.7 V), the diode does not work. When the conduction pressure drop is exceeded, excessive voltage will consume the internal resistance of the signal source. From the energy point of view, this is only the energy conversion process, so the whole circuit still conforms to the energy conservation.

Therefore, we cannot think that the current, voltage, or electric power is amplified. The amplification circuit violates the Conservation Law of energy. It is indeed an amplification of energy, but its energy gain is not nothing, it is provided by the power supply, and the energy required for each component to work in the circuit is provided by the "Source", and the energy obtained can be converted by consumption or storage, however, the whole process satisfies the Conservation Law of energy.