Novel log-domain frequency-adaptive filter

Abstract

A topology for realising log-domain frequency-adaptive filters is proposed in this article. According to this the side effects of the on-chip capacitor deviations, generated by the technology tolerances, are efficiently compensated giving a constant cutoff frequency. Also, the cutoff frequency is automatically controlled and readjusted by the frequency of an external reference signal. The correct operation of the proposed scheme has been verified through simulations by employing transistor models provided by a typical 0.35 µm BiCMOS technology.

Keywords:

• adaptive filters
• automatic tuning
• filter compensation
• log-domain filters
• companding filters