I. Exploring why analog circuits need isolated power supplies
Secondly, isolated power supplies prevent signal propagation and interference. Analog circuits typically amplify and process input signals, such as amplifying audio signals or sensor outputs. Without isolated power supplies, noise and interference in the input signals could propagate through the power lines to other devices and circuits, causing instability or even malfunctions in those devices. Using isolated power supplies effectively isolates these interference signals, ensuring the independence and stability between the input and output of analog circuits.
In addition, isolated power supplies provide electrical compatibility and signal isolation. Many analog circuits may need to be connected to other devices, such as audio and imaging equipment. These devices may have different ground potentials, and without isolated power supplies, potential differences in the ground loops can occur, causing noise and distortion. Using isolated power supplies separates the ground loops between different devices, ensuring signal integrity and quality.
Finally, it's important to note that the selection and use of an isolated power supply need to be tailored to the specific application requirements. Different analog circuits may have different operating voltage and current requirements, so the rated voltage and current range of the power supply must be considered when selecting one. Furthermore, the power supply's transmission and power efficiency, among other performance indicators, should be carefully considered to ensure optimal performance.
II. 10 Essential Tips for Learning Analog Circuits
1. Field-effect transistors and BJTs differ significantly in their operation: In BJTs, the charge carriers are holes or a small number of ejected "minority carriers," while in FETs, the charge carriers are a relatively larger number of free electrons, "majority carriers," which are several orders of magnitude more in number.
2. Forward bias of the emitter and reverse bias of the collector are prerequisites for the BJT to operate in amplification mode. There are three connection methods: common base, common emitter, and common collector. The method to distinguish between the three configurations is: common emitter (base input, collector output); common collector (base input, emitter output); common base (emitter input, collector output).
3. Key parameters of a transistor: current amplification factor β, and reverse current between electrodes.
4. Because J-FETs have a very high Rgs, electrostatic discharge (ESD) must be avoided during use, otherwise gate breakdown can easily occur. Additionally, all limiting parameters should be carefully considered during circuit design to ensure they are not exceeded. When using a J-FET as a variable resistor, ensure the device is properly biased and prevent it from entering the constant current region.
5. Emitter bias circuit: used to eliminate the influence of temperature on the static operating point.
6. Comparison of three BJT amplifier circuits: Common-emitter amplifier circuit: amplifies both current and voltage. Common-collector amplifier circuit: amplifies only current, follows voltage, large input resistor R, small output resistor R, used as both input and output stages. Common-base amplifier circuit: amplifies only voltage, follows current, good high-frequency characteristics.
7. Decoupling capacitor: The output signal capacitor is grounded to filter out high-frequency noise. Bypass capacitor: The input signal capacitor is grounded to filter out high-frequency noise. AC signals are treated as short-circuited for both types of capacitors.
8. In addition to selecting the correct parameters and making the correct calculations, the most important thing to emphasize when using MOS-FET is still the issue of anti-static operation. During circuit debugging, soldering, and installation, it is essential to strictly follow the anti-static procedures.
9. The mainstream current in ICs flows from the emitter to the collector, while the bias current flows from the emitter to the base (Ib). The circuit that provides current to the base, relative to the main circuit, is called the bias circuit.
10. A field-effect transistor (FET) has three aluminum electrodes: gate (g), source (s), and drain (d). These correspond to the base (b), emitter (e), and collector (c) of the transistor, respectively. <The source emits something, so it corresponds to the emitter (e). The gate acts like a gate, similar in function to the base.> The P-type substrate is typically connected to the gate (g).
