Wide Dynamic Range CMOS Pseudo-differential Current Conveyors: CMOS Realizations and Applications
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Wide Dynamic Range CMOS Pseudo-differential Current Conveyors: CMOS Realizations and Applications Soliman A. Mahmoud
Received: 12 April 2012 / Revised: 7 August 2012 © Springer Science+Business Media, LLC 2012
Abstract This paper presents two new CMOS realization circuits of the pseudodifferential current conveyor (PDCC) in which the second realization is a modified version of the first one. The modified PDCC has a wide dynamic input and output ranges with low distortion. The PDCC CMOS circuits are formed from two stages, input stage and output stage, and operating under a supply voltage of ±1.5 V. The input stage of the PDCC is realized using two wide linear range transconductors, and the output stage consists of a class AB push-pull network, which guarantees high current driving capability and low standby current. The first realization of PDCC exhibits dynamic input range of ±1.4 V with a total standby power dissipation of 4.08 mW, while the second realization of the PDCC exhibits a wide dynamic input range of ±2.1 V with a total standby power dissipation of 3.68 mW. The PDCC is used to realize mixed-mode fully differential VGA and a differential-mode bandpass filter. PSPICE simulations of the proposed PDCC and its based applications are given using 0.25-μm CMOS technology from TMSC MOSIS. Keywords Current conveyors · Transconductors · Filters · Variable gain amplifiers 1 Introduction Since its first introduction, by Sedra and Smith [17] in 1970, the second-generation current conveyor (CCII) has proved to be a versatile analog building block that S.A. Mahmoud () Electrical and Computer Engineering Dept., Sharjah University, Sharjah University City, Sharjah, 27272, United Arab Emirates e-mail: [email protected] S.A. Mahmoud Electrical Engineering Dept., Fayoum University, Fayoum, Egypt e-mail: [email protected]
Circuits Syst Signal Process Fig. 1 Symbol of the DCC
can be used to implement numerous high-frequency analog signal applications, like filters [1, 2, 5, 11, 18, 19, 23] and current-mode oscillators [20]. However, when it comes to applications demanding differential or floating inputs like impedance converters and current mode instrumentation amplifiers, which also require two high input impedance terminals, a single CCII block is no more sufficient. In addition, most of these applications employ floating elements in order to minimize the number of used CCII blocks. For this reason and in order to provide two high input impedance terminals, the differential current conveyor (DCC) is needed [12]. In addition, most modern high-performance analog integrated circuits incorporate fully differential signal paths. This is because fully differential circuit configurations, when compared to their single-ended counterparts, exhibit higher rejection capabilities to clock-feed-through, charge injection errors, and power supply noises, as well as larger output dynamic range, higher design flexibility, and reduced harmonic distortion [6–8, 10, 13, 14]. Besides, most modern systems employ both analog and digi
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