In this study, a trapezoidal-rule integrator and inverting a differentiator are employed to form the transfer function of an approaching integrator in the Z domain. The integrator was implemented to verify the feasibility of the technique, and the integrator exhibited an operating frequency of 1.45 to 6 GHz. Adding microwave integrators to a receiver's radio frequency (RF) circuits in a communication link improves the signal-to-noise ratio (SNR). As a result, an experimental environment was constructed in a wireless local area network (WLAN) band (2400 to 2483.5 MHz). In addition, the RF transmitter emitted the main signal at 2.45 GHz, which included the high-frequency interfering signals at 3.5, 4.5, and 5.5 GHz. The integrators and low-pass filters were implemented to perform signal analysis of the RF signals. To compare the interference suppression of the integrators with the interference suppression of the original and low-pass filters, the receiving power of the main signal and the interfering signals from the different frequencies in the end of the receiver were analyzed. The experimental results indicated that inserting integrators into RF circuits improved the SNR of the communication link by up to 10 dB.
2. Sun, Y. and T. Pratt, "Narrowband PLC SIMO-based interference suppression with zero-forcing," IEEE Power Deliv., Vol. 28, No. 4, 2022-2029, Apr. 2013.
3. Gupta, A. S. and A. Singer, "Interference suppression for memoryless nonlinear multiuser systems using constellation structure," IEEE Trans. Signal Processing, Vol. 56, No. 11, 5589-5604, Nov. 2008.
4. Zhou, H. and B. Wen, "Radio frequency interference suppression in small-aperture high-frequency radars," IEEE Geo. Remote Sensing Lett., Vol. 9, No. 4, 788-792, Apr. 2012.
5. Perez-Solano, J. J., S. Felici-Castell, and M. A. Rodriguez-Hernandez, "Narrowband interference suppression in frequency-hopping spread spectrum using undecimated wavelet packet transform," IEEE Trans. Vehicular Tech., Vol. 57, No. 3, 1620-1629, Mar. 2008.
6. Talmon, R., I. Cohen, and S. Gannot, "Single-channel transient interference suppression with diffusion maps," IEEE Trans. Audio, Speech, and Language Processing, Vol. 21, No. 1, 132-144, Jan. 2013.
7. Bottomley, G. E., "CDMA downlink interference suppression using I/Q projection," IEEE Trans. Wireless Comm., Vol. 2, No. 5, 890-900, May 2003.
8. Clarke, P. and R. C. de Lamare, "Low-complexity reduced-rank linear interference suppression based on set-membership joint iterative optimization for DS-CDMA systems," IEEE Trans. Vehicular Tech., Vol. 60, No. 9, 4324-4337, Sept. 2011.
9. De Lamare, R. C. and P. S. R. Diniz, "Blind adaptive interference suppression based on setmembership constrained constant-modulus algorithms with dynamic bounds," IEEE Trans. Signal Processing, Vol. 61, No. 5, 1288-1301, May 2013.
10. Hombs, B. and J. S. Lehnert, "Multiple-access interference suppression for MC-CDMA by frequency-domain oversampling," IEEE Trans. Comm., Vol. 53, No. 4, 677-686, Apr. 2005.
11. Glisic, S. G., Z. B. Nikolic, B. Dimitrijevic, and G. K. Woodward, "Multilayer LMS interference suppression algorithms for CDMA wireless network," IEEE Trans. Comm., Vol. 48, No. 8, 1413-1422, Aug. 2000.
12. Al-Alaoui, M. A., "Novel IIR differentiator from the Simpson rule," IEEE Trans. Circuits Systems — I, Vol. 41, No. 2, 186-187, Feb. 1994.
13. Tseng, C.-C., "Design of fractional order digital FIR differentiators," IEEE Signal Processing Letters, Vol. 8, No. 3, 77-79, Mar. 2001.
14. Kumar, B. and S. C. Dutta-Roy, "Design of digital differentiators for low-frequencies," Proc. IEEE, Vol. 76, No. 3, 287-289, Mar. 1988.
15. Pei, S. C. and J. J. Shyu, "Analytic closed form matrix for designing high order digital differentiators using eigenapproach," IEEE Trans. Signal Processing, Vol. 44, No. 3, 698-701, Mar. 1996.
16. Al-Alaoui, M. A., "A class of second-order integrators and low-pass differentiators," IEEE Trans. Circuits Systems — I, Vol. 42, No. 4, 220-223, Apr. 1995.
17. Hsue, C.-W., L.-C. Tsai, and K.-L. Chen, "Implementation of first-order and second-order microwave differentiators," IEEE Trans. Microwave Theory Tech., Vol. 52, No. 5, 1443-1448, May 2004.
18. Oppenheim, A. V. and R. W. Schafer, Discrete-time Signal Processing, Prentice-Hall, Englewood Cliffs, NJ, 1998.
19. Tsai, L. C. and C. W. Hsue, "Dualband bandpass filter using equal length coupled serial shunted lines and Z-domain technique," IEEE Trans. Microwave Theory Tech., Vol. 52, No. 4, 1111-1117, Apr. 2004.
20. Chang, D.-C. and C.-W. Hsue, "Design and implementation of filters using transfer functions in the Z domain," IEEE Trans. Microwave Theory Tech., Vol. 49, No. 5, 979-985, May 2001.
21. Chang, D.-C. and C.-W. Hsue, "Wide-band equal-ripple filters in nonuniform transmission lines," IEEE Trans. Microwave Theory Tech., Vol. 50, No. 4, 1114-1119, Apr. 2002.
22. Loyka, S. and A. Kouki, "Using two ray multipath model for microwave link budget analysis," IEEE Antennas and Propagation Magazine, Vol. 43, No. 5, 31-36, Oct. 2001.
23. Parsons, J. D., The Mobile Radio Propagation Channel, 2nd Ed., Wiley, New York, 2000.