School of Electronics and Communication Engineering, REVA UNIVERSITY, Bengaluru, India

Biography: Dr. Rohini Deshpande has 32 years of teaching and research experience. She has many research publications in reputed national/international journals and conferences. Some of the journals where her research articles published are Elsevier, IET, Springer, Wiley Intersciences having good impact factors. She has published 36 papers in peer reviewed international journals book series and conferences of good reputation.
As per Google Scholar, She has Citation Index of 45 and h-index of 3 as on 1st April 2019. Her research fields are design techniques of digital filters, Energy harvesting, Mechatronics etc. She is guiding 5 PhD students. She is a reviewer of various reputed journals and conferences and chaired many conferences. She is a life member ISTE, IETE, CSI and senior member of IEEE. She is listed in 30th anniversary Pearl’s Edition of Marquis' Who's Who in the World. FACE of Delhi has bestowed “VIDYA VIBHUSHAN” award upon her based on self-profile in 2015. She has filed for two Indian patents. She attended International conferences CECNet 2018 & 2019 as invited speaker held at Taiwan and Thailand respectively. Presently she is working as professor in the school of electronics and communication engineering of REVA University.

Qualification:
• Ph. D. in Digital Signal Processing from Guru Gobind Singh Indraprasta (GGSIP) University New Delhi.
• M. E., Electronics and Communications from Delhi University. New Delhi
• B. E., Electronics and Communication Engineering from Gulbarga University, Gulbarga

Speech Title: Design Techniques for Innovative Notch Filters

Abstract: In this talk I am proposing few innovative application specific FIR notch filters that are free from most of the undesired features such as non-optimal design, ripple in pass bands, highly involved mathematical computations etc.

1. Maximally flat, linear phase FIR notch filter with controlled null width.
First part of the talk deals with design of a maximally flat, linear phase FIR notch filter with controlled null width. Design analyses carried out with first, third and fifth order zero derivative constraints of the amplitude response of the FIR filter at notch frequency is discussed. Detailed analysis in the research work discussed shows that the null width of a maximally flat, linear phase FIR notch filter can be controlled by suitable selection of individual zero odd order derivatives and also by the successive addition of zero odd order derivatives at the notch frequency ωd

2. FIR notch filter with highly narrow rejection bandwidth.
Design of FIR notch filters (NF) with highly narrow rejection bandwidth (RBW) is discussed. Reduction in the RBW can be achieved progressively in three stages. In the first stage an FIR notch filter is designed from a second order IIR prototype filter. For a given length L of the NF, the maximum permissible value of ‘r’ (the pole length of IIR prototype filter) is chosen to achieve very narrow RBW of the FIR filter. In the next stage by using an Amplitude Change Function (ACF):H(z)(2 – H(z)), the designed filter is sharpened. Consequently, the RBW of the resulting NF is reduced to almost half of the earlier value. In the third stage, RBW is further reduced by repeated sharpening of the filter by the same ACF.

3. IIR Bi-noch filter with reduced number of computations for the desired response.
A special case when two notch frequencies ω1 and ω2 of IIR bi-notch filters are such that [(cos ω1)(cos ω2) = -1/2] has also been discussed. The IIR bi notch filter design for this special case results reduction in the number of multipliers without affecting the response of the desired notch filter. For the above mentioned condition, the required design weights of FIR bi notch filter reduce to almost half in number resulting in reduced computations.

Keywords: Notch filter, Rejection bandwidth, Controlled nullwidth, Bi-notch filter