How do resistors achieve signal filtering and delay?

Resistors achieve signal filtering and delay functions in circuits, mainly relying on their combination with capacitors (or other energy storage components). The following is a detailed explanation of how resistors achieve signal filtering and delay:
Signal filtering
The combination of resistors and capacitors can form an RC filtering circuit, which is used to filter out high-frequency noise and interference signals in the circuit. There are two basic types of RC filtering circuits: low-pass filters and high pass filters.

Low pass filter: In this type of filter, resistors and capacitors are connected in series. When the signal passes through, high-frequency signals are attenuated or blocked due to the "short circuit" effect of capacitors, while low-frequency signals can pass smoothly. In this way, a low-pass filter can filter out high-frequency noise and retain low-frequency useful signals.
High pass filter: Unlike low-pass filters, high pass filters allow high-frequency signals to pass through while attenuating or blocking low-frequency signals. In a high pass filter, resistors and capacitors are connected in parallel to form a delay network. The energy of low-frequency signals is consumed by resistors, while high-frequency signals are transmitted through capacitors.

Signal delay
The combination of resistors and capacitors can also achieve signal delay function. This is usually achieved through RC delay circuits.

RC delay circuit: When the input signal arrives, the capacitor begins to charge through the resistor. During the charging process, there will be a certain delay in the output signal relative to the input signal. The delay time depends on the resistance of the resistor and the capacity of the capacitor. The larger the resistance value or capacitance value, the longer the delay time. This delay effect can be used in various circuit designs that require signal delay, such as pulse generators, flip flops, etc.

Implementation principle

Filtering principle: The implementation of filtering function mainly depends on the response characteristics of capacitors to signals of different frequencies. Capacitors have a lower impedance for high-frequency signals and a higher impedance for low-frequency signals. Therefore, in RC filtering circuits, high-frequency signals are more easily attenuated or blocked by capacitors, while low-frequency signals can pass smoothly.
Delay principle: The implementation of delay function depends on the process of charging and discharging capacitors. When the input signal arrives, the capacitor begins to charge and gradually accumulates charge. This charging process requires a certain amount of time, resulting in a delay in the output signal relative to the input signal. The length of the delay time depends on the resistance of the resistor and the capacity of the capacitor.

In summary, by combining resistors with energy storage components such as capacitors, signal filtering and delay functions can be achieved. These functions have wide application value in electronic circuit design, such as signal processing, communication, control systems, and other fields.