Convert digital signal of 100KHz to sine wave. This can be used to generate sine wave from a generators of square wave such as microprocesors or 555. The circuit that converts the signal is passive band pass filter with maximum at the input frequency (100KHz). The band pass filter is formed by serial conection of low pass and high pass filter. The frequency response can be seen from the f plot, if you set the generator as sine. The Q factor measured from the f response is about Q=10 000
