Low-frequency compensation of FDNR low-pass filters

A solution to the problem of realizing an inductorless low-pass elliptic transfer function has been proposed in which grounded FDNR elements are realized. The practical bias requirements for a resistive branch to ground have resulted in nonideal low-frequency rolloff in the passband. A simple technique is proposed to prevent low-frequency rolloff, to ensure direct-coupled operation, and at the same time to satisfy the practical constraints imposed by the bias requirements of the operational amplifiers.