In the design of electronic circuits, commonly used filters are divided into high-pass filters, low-pass filters, band-stop filters, and band-pass filters, and these four filters are collectively referred to as active filters. Let's talk about the working principle and application of this low-pass filter separately.
Low-pass filter characteristics: allow low-frequency signals to pass and attenuate high-frequency signals. Amplitude-frequency characteristics when the signal is at low frequency:
The above figure is a passive integrator circuit after the simplified circuit. serial rs232 to wifi converter Simply analyze this integrator circuit, assuming that its time constant T needs to be greater than its signal pulse width, and since T=RC, the working principle of this circuit is:
Assuming that the input signal is a rectangular pulse wave (or a sine wave), when the first pulse wave appears, a current is generated at the input terminal, and by charging R3 and C41 (the voltage across the capacitor will not change suddenly), this At this time, the voltage on the capacitor C41 increases slowly. When the pulse passes, the signal UIN at the rs232 to ethernet adapter input terminal will be 0 (the voltage across the capacitor will not change suddenly), so the time constant T will be relatively large, and its discharge will be relatively large. becomes very slow.
Slowly, the second pulse comes again. At this time, since the previous electricity is still not discharged, we can know that when the input pulse wave is denser, our UOUT will be larger.
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