A novel complex filter topology realized using current feedback operational amplifiers as active elements is introduced in this paper. Offered benefits are the low-voltage operation capability and the requirement for employing only grounded passive elements. Two application examples are provided, where the frequency behavior of the derived filters fulfills the ZigBee and Bluetooth standards, respectively. Their performance evaluation has been done through simulation results at postlayout level, using MOS transistor models provided by AMS C35B4 CMOS process. 1. Introduction Low-IF transceiver architectures suffer from the presence of image signals, caused by the downconversion operation realized by the complex mixing. Unfortunately, due to their symmetrical response around the dc, the conventional real filters do not have the capability for removing the image signals. In order to overcome this problem, a new class of filters denoted by complex filters has been introduced in the literature. Complex filters are constructed from two-path networks, where a pair of signals with equal amplitudes and quadrature phases ( and channels) is applied at their inputs. The concept of complex signal processing is formally described in [1–3]. A significant research effort has been already performed in the literature for designing complex filters suitable for low-IF receivers. The discrete-time topologies in [4, 5] have been derived using the switched capacitor and switched current techniques, respectively. Continuous-time filters have been introduced in [6–21]. The topologies in [6, 7] are companding filters realized by utilizing bipolar transistors. The concept of conventional linear continuous-time filtering and MOS transistors has been used in [8–21]. The topologies in [8–14] offer the capability for resistorless realization and this originated from the employment of the operational transconductance Amplifiers (OTAs) [8–12] or current mirrors (CMs) [13, 14] as active elements. Second generation current conveyors (CCIIs) in single form [15, 16] or fully differential form [17] have been utilized for realizing current-mode complex filters. CCIIs configured as current followers (CFs) and voltage followers (VFs) have been employed in [18], while CCIIs as VFs have been used in [19]. In the topology in [20] operational amplifiers (op-amps) have been used as active elements, while in [21] a number of voltage-mode and current-mode realizations based on transconductance, transresistance, and current amplifiers have been presented and evaluated. Current feedback operational
References
[1]
W. M. Snelgrove and A. S. Sedra, “State-space synthesis of complex analog filters,” in Proceedings of the European Conference on Circuit Theory and Design (ECCTD '81), pp. 420–424, 1981.
[2]
G. R. Lang and P. O. Brackett, “Complex analogue filters,” in Proceedings of the European Conference on Circuit Theory and Design (ECCTD '81), pp. 412–419, 1981.
[3]
K. W. Martin, “Complex signal processing is not complex,” IEEE Transactions on Circuits and Systems I, vol. 51, no. 9, pp. 1823–1836, 2004.
[4]
K. Suzuki, M. Ugajin, and M. Harada, “A 5th-order switched-capacitor complex filter for low-IF narrowband wireless receivers,” in Proceedings of the IEEE Radio and Wireless Symposium (RWW '10), pp. 420–423, New Orleans, Lo, USA, January 2010.
[5]
A. Worapishet, R. Sitdhikorn, A. Spencer, and J. B. Hughes, “A multirate switched-current filter using class-AB cascoded memory,” IEEE Transactions on Circuits and Systems II, vol. 53, no. 11, pp. 1323–1327, 2006.
[6]
N. Y. Voo, M. Teplechuk, and J. I. Sewell, “General synthesis of complex analogue filters,” IEE Proceedings G, vol. 152, pp. 7–15, 2005.
[7]
C. Psychalinos, “Low-voltage log-domain complex filters,” IEEE Transactions on Circuits and Systems I, vol. 55, no. 11, pp. 3404–3412, 2008.
[8]
P. Andreani and S. Mattisson, “On the use of Nauta's transconductor in low-frequency CMOS gm-C bandpass filters,” IEEE Journal of Solid-State Circuits, vol. 37, no. 2, pp. 114–124, 2002.
[9]
J. B. Hughes, A. Spencer, A. Worapishet, and R. Sitdhikorn, “1？mW CMOS polyphase channel filter for Bluetooth,” IEE Proceedings: Circuits, Devices and Systems, vol. 149, no. 5-6, pp. 348–354, 2002.
[10]
A. A. Emira and E. Sánchez-Sinencio, “A pseudo differential complex filter for bluetooth with frequency tuning,” IEEE Transactions on Circuits and Systems II, vol. 50, no. 10, pp. 742–754, 2003.
[11]
B. Guthrie, J. Hughes, T. Sayers, and A. Spencer, “A CMOS gyrator low-IF filter for a dual-mode Bluetooth/ZigBee transceiver,” IEEE Journal of Solid-State Circuits, vol. 40, no. 9, pp. 1872–1878, 2005.
[12]
J. Mahattanakul and P. Khumsat, “Structure of complex elliptic Gm-C filters suitable for fully differential implementation,” IET Circuits, Devices and Systems, vol. 1, no. 4, pp. 275–282, 2007.
[13]
C. Laoudias and C. Psychalinos, “Low-voltage bluetooth/ZigBee complex filter using current mirrors,” in Proceedings of the IEEE International Symposium on Circuits and Systems: Nano-Bio Circuit Fabrics and Systems (ISCAS '10), pp. 1268–1271, Paris, France, June 2010.
[14]
C. Laoudias and C. Psychalinos, “1.5？V complex filters using current mirrors,” IEEE Transactions on Circuits and Systems II, vol. 59, pp. 575–579, 2011.
[15]
X. Zhang, X. Ni, M. Iwahashi, and N. Kambayashi, “Realization of universal active complex filter using CCIIs and CFCCIIs,” Analog Integrated Circuits and Signal Processing, vol. 20, no. 2, pp. 129–137, 1999.
[16]
M. T. Abuelma'atti and S. M. Al-Shahrani, “A new polyphase current-mode filter using programmable-gain current-controlled current-conveyor,” WSEAS Transactions on Electronics, vol. 2, no. 4, pp. 138–141, 2005.
[17]
E. A. Soliman and S. A. Mahmoud, “New CMOS fully differential current conveyor and its application in realizing sixth order complex filter,” in Proceedings of the IEEE International Symposium on Circuits and Systems (ISCAS '09), pp. 57–60, May 2009.
[18]
H. A. Alzaher and M. K. Alghamdi, “A CMOS bandpass filter for low-IF Bluetooth receivers,” IEEE Transactions on Circuits and Systems I, vol. 53, no. 8, pp. 1636–1647, 2006.
[19]
H. Alzaher, M. Al-Ghamdi, and M. Ismail, “CMOS low-power bandpass if filter for Bluetooth,” IET Circuits, Devices and Systems, vol. 1, no. 1, pp. 7–12, 2007.
[20]
H. Alzaher, “A CMOS highly linear digitally programmable active-RC design approach,” IEEE Transactions on Circuits and Systems I, vol. 58, pp. 2636–2646, 2011.
[21]
H. Alzaher, N. Tasadduq, and F. Al-Ammari, “Optimal low power complex filters,” IEEE Transactions on Circuits and Systems I, vol. 60, pp. 885–895, 2013.
[22]
M. T. Abuelma'atti and S. M. Al-Shahrani, “A new polyphase mixed-mode bandpass filter section using current-feedback operational amplifiers,” WSEAS Transactions on Electronics, vol. 2, no. 4, pp. 128–131, 2005.
[23]
M. ün, “Implementation of polyphase filter section with CFAs,” Frequenz, vol. 58, no. 9-10, pp. 221–224, 2004.
[24]
C. Sánchez-López, “Pathological equivalents of fully-differential active devices for symbolic nodal analysis,” IEEE Transactions on Circuits and Systems I, vol. 60, pp. 603–615, 2013.
[25]
C. Sánchez-López, F. V. Fernández, E. Tlelo-Cuautle, and S. X.-D. Tan, “Pathological element-based active device models and their application to symbolic analysis,” IEEE Transactions on Circuits and Systems I, vol. 58, pp. 1382–1395, 2011.
[26]
G. Raikos and C. Psychalinos, “Low-Voltage current feedback operational amplifiers,” Circuits, Systems, and Signal Processing, vol. 28, no. 3, pp. 377–388, 2009.
