Principles of choosingchip resistors
1. Choose according to the characteristics of the circuit
High-frequency circuit: The smaller the distribution parameter, the better. High-frequency resistors such as metal film resistors and metal oxide film resistors should be used.
Low-frequency circuit: both wire-wound resistors and carbon film resistors are applicable.
Decoupling circuit, filter circuit: There is no strict requirement on resistance change, any type of resistor is applicable.
Power amplifier circuit, bias circuit, sampling circuit: The circuit has relatively high requirements for stability, and a resistor with a small temperature coefficient should be selected.
2. Choose according to the resistance and error of the resistor
Resistance selection: The principle is that the difference between the nominal resistance of the resistor used and the required resistance is as small as possible.
Error selection: The error of the resistor required by the time constant RC circuit is as small as possible. Generally, within 5% can be selected. For the decoupling circuit, the feedback circuit, the filter circuit, and the load circuit have not too high requirements for errors. Optional 10%-20% resistors.
3. Select according to the limit parameters of the resistor
Rated voltage: When the actual voltage exceeds the rated voltage, even if the power requirements are met, the resistor will be damaged by breakdown.
Rated power: The rated power of the selected resistor should be more than twice the actual withstand power to ensure the long-term reliability of the resistor in the circuit.
The following principles must be paid attention to:
1. Resistance stability
2. Working frequency
3. Load characteristics
4. Non-linear resistance