High-order BP Filter using Biquad Log-domain Method

High-order band-pass ladder filter based on Log-domain biquad functions is presented in this paper. High-order ladder filter is designed from RLC ladder filter prototype based on two types of biquad log-domain filters. Log-domain lossy and lossless integrator concepts are used to realize biquad log-domain filter in each type. Log-domain lossy integrator is easily realized by using 7 transistors and 1 grounded capacitor and log-domain lossless integrator is also easily realized by using log-domain lossy integrator by adding feedback to the input which consists of 8 transistors and 1 grounded capacitor. By adjusting bias current the frequency responses the filter can be obtain between 100 kHz and 100 MHz. This filter operates in transistor level which is suitable for operating in high frequency operation. A commercial array BJT technology is used in PSpice simulation.