Novel Second-Order Transfer Section for Frequency-Selective Response Generation in Comb Filters

Abstract

This article introduces a novel unified second-order filtering topology for standard band-reject (sBR) and inverting band-reject filter, enabling selective response generation. It is applied in the design of special comb filters that allow attenuation as well as amplification of specific bands. The presented solution offers several advantageous features in topology, enhanced cascadability, better parameter-setting performance, and the use of readily available off-the-shelf components, all while reducing overall costs. This is a significant improvement compared to the previous solutions in this field, which relied on a very expensive CMOS process. The topology employs a combination of an operational transconductance amplifier (OTA) and a current feedback amplifier. The intended center frequencies and transfer values of the comb filter are set to 50 Hz (-20 dB), 1 kHz (+26 dB), 10 kHz (+17 dB), and 100 kHz (-30 dB). The comb filter was experimentally verified via simulations as well as laboratory measurements utilizing LT1228 devices in a fabricated prototype.This article introduces a novel unified second-order filtering topology for standard band-reject (sBR) and inverting band-reject filter, enabling selective response generation. It is applied in the design of special comb filters that allow attenuation as well as amplification of specific bands. The presented solution offers several advantageous features in topology, enhanced cascadability, better parameter-setting performance, and the use of readily available off-the-shelf components, all while reducing overall costs. This is a significant improvement compared to the previous solutions in this field, which relied on a very expensive CMOS process. The topology employs a combination of an operational transconductance amplifier (OTA) and a current feedback amplifier. The intended center frequencies and transfer values of the comb filter are set to 50 Hz (-20 dB), 1 kHz (+26 dB), 10 kHz (+17 dB), and 100 kHz (-30 dB). The comb filter was experimentally verified via simulations as well as laboratory measurements utilizing LT1228 devices in a fabricated prototype.