To design a 3rd order Low Pass Filter (LPF) with a total gain of 20 dB and a cutoff frequency of 3 kHz using a minimum number of op-amps, a Sallen-Key topology can be employed. This topology allows for a high-order filter with fewer op-amps compared to other configurations.
The LPF can be implemented using resistors (R) and capacitors (C) in a specific arrangement. In this case, the Sallen-Key topology is used, where two resistors and two capacitors are connected in a specific configuration. The component values are determined based on the desired cutoff frequency and the order of the filter.
By following the design steps and calculations for a 3rd order Butterworth LPF, the values of the resistors and capacitors can be determined. These values can be selected based on design requirements and component availability.
The circuit consists of two resistors (R) and two capacitors (C) connected to an op-amp. The specific connections depend on the Sallen-Key topology. The op-amp is used to amplify the filtered signal, and the additional gain stage can be added to achieve the desired total gain of 20 dB.
It's important to note that this description provides a general overview of the design process and the components involved in constructing a 3rd order LPF. The actual implementation may require further analysis, calculations, and considerations specific to the chosen component values and design requirements. It's always recommended to simulate the circuit or consult relevant resources for a detailed understanding of the design and its specific characteristics.