Memristor BJT pair based low complex circuits for portable electronics P Michael Preetam Raj 1 • Arvind Subramaniam 1 • Souvik Kundu 1 Received: 19 January 2020 / Revised: 7 August 2020 / Accepted: 8 September 2020 / Published online: 16 September 2020 Ó Springer Science+Business Media, LLC, part of Springer Nature 2020 Abstract Circuits consisting of both memristor and bipolar junction transistor (BJT) were found to be extremely beneficial as the current driven by the transistor enhanced the memristive performances. In this work, memristor-BJT pair was considered and its electronic characteristics were investigated. The pair demonstrated the features of tunable current regulator with reduced circuit complexity. Importantly, the duo exhibited stable characteristics for a large range of frequency variations. Interestingly, the ameliorated linearity was obtained in the memristance-time characteristics. Most importantly, variable negative resistance (VNR) was achieved by modulating the current through the couple. This property was employed in solving linear equations that possess negative slope. In addition, VNR was utilized to implement a low circuit complexity based pulse signal generator with tunable amplitude and on duration. The abovementioned results were obtained through simulation and fabrication routes. The ideas proposed in this work pave the way for futuristic highly reliable oscillators and logic control circuits with reduced on-chip area for portable electronic systems. Keywords Memristor Á BJT Á Current regulator Á Variable negative resistance Á Pulse signal generator Á Portable electronics 1 Introduction Memristor the fourth basic electronic circuital element was first theoretically proposed by Leon Chua in 1971 [1]. Eventually realized at Hewlett-Packard labs in 2008 [2], it has been an intrigued alternative to conventional electronic devices [3–5]. Importantly, memristive systems have demonstrated improvements in terms of on-chip area (* 42%), power consumption (100 times) and latency (within 1 ns) when compared to the widely used transistor based systems [5–8]. In this regard, recently there have been numerous research interests to develop novel mem- ristive circuits and systems [8–14]. Owing to its compati- bility with the popular complementary metal oxide semiconductor (CMOS) fabrication process, prior studies have documented integration of memristors with CMOS devices [15–17]. However, the existing memristive circuits suffer with the drawback associated with nonlinear device characteristics, which ultimately results in erroneous memristive programming. In order to mitigate this issue, there is a need to explore novel memristor based nonlin- earity compensation circuits. An important electronic circuit which maintains con- stant current (despite the fluctuations in voltage) is the current regulator [18]. Such a functionality is extremely essential in several electrical, electronic, medical and chemical processing applications [19–22]. It is important to mention that the existing current regulators are disadvan- tageous in terms of device and circuit complexity [18, 23]. Hence, there exists a necessity to develop current regula- tors with reduced number of electronic components. A significant feature of an electronic system is the ability to unvaryingly execute its functionalities throughout a large range of external frequency variations [24, 25]. In this regard, efforts were devoted to develop electronic circuits in which the performance of the devices was barely affected with the variations in signal frequencies up to 50% of its mean value [26, 27]. However, such a low range of frequencies is inexpedient for numerous practical applica- tions [24, 25]. Thus, there is a requirement to develop circuits that are tolerable towards larger alterations in frequencies. & Souvik Kundu souvikelt@gmail.com; souvik.kundu@hyderabad.bits- pilani.ac.in 1 Department of Electrical & Electronics Engineering, Birla Institute of Technology and Science (BITS) Pilani, Hyderabad Campus, Hyderabad 500078, India 123 Analog Integrated Circuits and Signal Processing (2021) 107:239–247 https://doi.org/10.1007/s10470-020-01716-8