Dual-mode OTA based biquadratic filter suitable for current-mode applications

In this paper, a dual mode single-input multiple-output (SIMO) biquadratic filter structure is presented using multi-output Operational Transconductance Amplifiers (OTAs). Using a simple switch, the filter operates alternatively in trans-admittance mode or current mode. Selection of working mode using a switch provides flexibility for current-mode design. The filter natural angular frequency (ω0) and quality factor (Q) can be orthogonally adjusted both in current mode and trans-admittance mode operation. The proposed structure has simple structure, requiring only four OTAs and two grounded capacitors. The proposed structure is the only SIMO structure where the working mode is selected using a switch. The proposed biquadratic structure is realized using 0.35 µm CMOS technology, and, circuit functionality is verified by SPICE simulations.