Microstrip and Coplanar Band-Pass Filters Using MMIC Negative Resistance Circuits For Insertion Losses Compensation And Size Reduction

A new band-pass filter design technique is presented which uses classical passive interdigitated filters assisted by a MMIC active component circuit. The MMIC component performs a negative resistance with an associated imaginary part. By using this component, the negative resistance leads to compensate for the losses of the passive filter while the imaginary part leads to reduce significantly the length of the resonator. Two filters, implemented in microstrip and coplanar technologies have been designed and tested to demonstrate our approach.