Discussion reply: low pass filter

ÿA low pass filter can be defined as low frequencies that exist above a ÿcutoff frequency that will be permitted through a filter. A high-pass ÿfilter operates below the cutoff frequency permitting higher frequencies ÿto pass through the filter. Low-pass filters are used to smooth out an ÿimage, and they can help remove the aliasing effect. A high pass filter ÿcan be used to sharpen an image and work to remove noise. The BJT ÿamplifier can act as a filter based on the quantity being amplified by ÿthe circuit, so it could be power, voltage, or current being amplified.ÿÿ
An ÿinternal capacitor works to form a low-pass filter that has external ÿresistors. The external capacitance with a low frequency has a high ÿimpedance making the gain low, and when high, there is a low impedance ÿand high gain. When it is a high frequency, the coupling with the bypass ÿcapacitor is a short circuit and cannot affect the response of the ÿamplifier.ÿ
Having two cutoff frequencies will cause the higher to decrease and the lower frequencies to increase.ÿÿ
When ÿmulti-stage amplifiers are determined, the bandwidth can be determined ÿby the more stages there are, the steeper the high and low pass filters ÿwill be. If and when the stages are capacitively coupled, then each ÿcapacitor will roll off the chosen frequency.ÿÿ