Analysis, Design, and Order Estimation of Least-Squares FIR Equalizers for Bandwidth Extension of ADCs
- 25 Downloads
In modern mixed-signal systems, it is important to build the conversion components with a flat frequency response over their full Nyquist frequency band. However, with increasing circuit speed, it is becoming more difficult to achieve this, due to limitations of the analog front-end circuits. This paper considers finite-length impulse-response (FIR) filters, designed in the least-squares sense, for the bandwidth extension of analog-to-digital converters, which is one of the most important applications in frequency response equalization. The main contributions of this paper are as follows: Firstly, based on extensive simulations, filter order-estimation expressions of the least-squares designed equalizers are derived. It appears to be the first time that order-estimation expressions are presented for any least-squares designed FIR filter. These expressions accurately estimate the order required for given specifications on the targeted extended bandwidth systems. Secondly, based on the derived order-estimation expressions, systematic design procedures are presented, which contribute to reducing the design time. Finally, a relation between the dynamic-range degradation and the system parameters is also derived and verified in the paper.
KeywordsADC Bandwidth extension FIR filter Frequency response equalization Filter order estimation Least-squares design
This work was supported by the National Natural Science Foundation of China (Nos. 61701509 and 61704191).
- 1.J. Hancock, Advantages and disadvantages of using DSP filtering on oscilloscope waveforms. Application Note 1494, Agilent Technologies (2004), https://www.eetimes.com/document.asp?doc_id=1275751
- 2.S.C. Chapra, R.P. Canale, Numerical Methods for Engineers (McGraw-Hill, Maidenherd, 2012)Google Scholar
- 4.Z. Hao, Y. Peng, Research on analog bandwidth enhancement technology for digital storage oscilloscope. in Proceedings of IEEE International Conference on Electronic Measurement and Instruments (2011), pp. 217–220Google Scholar
- 9.W.J. Kenneth, Digital Signal Processing (DSP) in Oscilloscopes. Application Note (LeCroy Corporation, New York, 2010)Google Scholar
- 13.B. Murmann, C. Vogel, H. Koeppl, Digitally enhanced analog circuits: system aspects. in Proceedings of IEEE International Symposium on Circuits and Systems (2008), pp. 560–563Google Scholar
- 15.J.J. Pickerd, DSP in high performance oscilloscopes. TektronixTM White Paper (2005)Google Scholar
- 18.Z.U. Sheikh, A. Eghbali, H. Johansson, Linear-phase FIR digital differentiator order estimation. in Proceedings of European Conference on Circuit Theory and Design (Linköping, Sweden, 2011), pp. 29–31Google Scholar
- 22.Y. Wang, H. Johansson, H. Xu, J. Diao, Minimax design and order estimation of FIR filters for bandwidth extension of ADCs. in Proceedings of IEEE International Symposium on Circuits and Systems (2016), pp. 2186–2189Google Scholar
- 23.L. Wanhammar, H. Johansson, Digital Filters Using Matlab (Linköping University, Linköping, 2011)Google Scholar