Multiple-Input Universal Filter and Quadrature Oscillator Using Multiple-Input Operational Transconductance Amplifiers

This paper presents a new multiple-input single output voltage-mode universal biquad filter based on multiple input operational transconductance amplifiers (MI-OTA). This work demonstrates that the multiple-input OTA based universal filter can provide more filtering responses and other benefits, compared to conventional OTA based one. The filter provides electronic and orthogonal control of the natural frequency and the quality factor. Furthermore, a two-phase quadrature oscillator can be obtained by slightly modifying the proposed universal filter while the condition and frequency of oscillation can be controlled orthogonally and electronically. The performance of the proposed circuit is evaluated in Cadence environment using the TSMC 0.18 fim CMOS technology. The voltage supply is 1.2 V and the power dissipation of the MI OTA is 24 fiW. For 1% third intermodulation distortion (IMD3) the dynamic range of the band pass filter is 78.6 dB. In addition, the proposed filter and oscillator are investigated through experiment tests using LM13700 commercially available OTA.