When selecting passive and active components, the following factors usually need to be considered:

Passive component selection factors:

Frequency characteristics: Different passive components exhibit varying performance at different frequencies and need to be selected based on the operating frequency range.

Loss: For example, the insertion loss of filters, couplers, etc. should be low to reduce signal attenuation.

Power capacity: Ensure the ability to withstand the expected input power and avoid damage.

Size and packaging: Choose the appropriate size and packaging form based on the layout and space constraints of the circuit board.

Price: Cost is also an important consideration when choosing cost-effective devices while meeting performance requirements.

Selection factors for active devices:

Gain: Select devices with appropriate gain based on the system's requirements for signal amplification.

Noise factor: Especially in applications that require high signal quality, active devices with low noise factor should be selected.

Linearity: For systems that handle large signals or complex modulated signals, devices with good linearity are required to avoid signal distortion.

Working voltage and current: should match the power supply of the system.

Stability: Active devices should be able to maintain stable performance under different working conditions.

Temperature characteristics: Consider the performance changes of the device under different temperature environments.

For example, if designing a high-frequency communication system, it is necessary to focus on the loss and filtering characteristics of passive filters at high frequencies; For active amplifiers, it is important to consider parameters such as gain, noise figure, and linearity.

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