Throughout my electronics career I have found the Sallen-Key filter to be an excellent tool in my circuit design toolset. It is an active filter… which means it shapes the signal using devices such as op amps. What makes it so attractive is actually its simplicity and adaptability. How Does It Work? A Sallen-Key filter […]
Filter
Band Stop Filter Circuit: Explained with Formulas
Another name for a band Stop Filter is the Notch Filter, which is designed to block and reject all frequencies that fall between its two cut-off frequency points, however all frequencies that are on the outer sides of this range, are allowed to pass through. A straightforward band-pass filter is created when we combine a simple […]
Understanding State Variable Filter Circuit with Formulas
In my electronic engineer profession, often times I have to use one of these state variable filters. These are actually specific types of active filters that are used in electronic circuits. These are built using one or more integrators positioned in a certain feedback arrangement. Whenever We have the requirement for an exact quality factor (Q factor) output, […]
Understanding Butterworth Filter Circuits with Formulas
We know that the Butterworth filter is a useful tool for electronics professionals but there is a trade-off with its performance. It is superior to other filter types in that it produces a completely flat response in the passband and stopband, but this ideal characteristic comes at the price of a wider transition band. This transition […]
Understanding Second Order Filter Circuits with Formulas
Second-order filters, often known as VCVS filters since their operational amplifier works like a Voltage Controlled Voltage Source amplifier, are a critical category in active filter design. These serve as fundamental elements for the construction of higher-order filter circuits, extending on previously researched active first-order RC filters. Our analysis of analog filters has included both passive […]
Understanding Active Band Pass Filter Circuits with Formulas
Before we begin our tutorial on active band pass filter circuits, let’s first look at the passband characteristics of several filter types. Low-Pass Filters (LPFs): An LPF’s passband begins at 0 Hz (DC) and extends to the set cut-off frequency (fC). This cut-off frequency corresponds to -3 dB with respect to the maximum passband gain. […]