China
Africa
Explore chapters and articles related to this topic
High-Performance Analog Circuits
Published in Wai-Kai Chen, Analog and VLSI Circuits, 2018
Chris Toumazou, Alison Payne, John Lidgey, Alicja Konczakowska, Bogdan M. Wilamowski
The current conveyor is a versatile broadband analog amplifier that is intended to be used with other circuit components to implement many analog signal-processing functions. It is an analog circuit building block in much the same way as a voltage op-amp, but it presents an alternative method of implementing analog systems that traditionally have been based on voltage op-amps. This alternative approach leads to new methods of implementing analog transfer functions, and in many cases the conveyor-based implementation offers improved performance when compared to the voltage op-amp-based implementation in terms of accuracy, bandwidth, and convenience. Circuits based on voltage op-amp are generally easy to design since the behavior of a voltage op-amp can be approximated by a few simple design rules. This is also true for current conveyors, and once the appropriate design rules are understood, the application engineer is able to design conveyor-based circuits just as easily.
Oscillator using recent CAB with grounded capacitors, independent controls and low resistance output
Published in Australian Journal of Electrical and Electronics Engineering, 2023
The real behaviour of an analog circuit can be studied only after the considerations of many issues, that affect the circuit. These are the non-ideal aspects of active and passive devices, parasitic elements associated with the circuit topology and the design issues arising out of these aspects. The current conveyor-based circuits are good from non-ideality concerns, as the voltage and current transfer gains remain close to ideal unity values till high frequency of operation. This property is attributed to the CMOS designs, which have become a de-facto standard owing to this feature. The only concern to be dealt with is very high frequency operation, which suffers either due to the finite bandwidth of voltage and current transfer gain or due to circuit topology. The role of parasitic elements is important for the topology-dependent non-idealities. The proposed topology is not ideally suited for very high frequency operation, due to a resistive capacitive series combination at one of the two X terminals. The resistive-capacitive shunt at the Z terminal is, however, ideal for parasitic absorption at that node. The various parasitic elements’ involvement can be shown along with the desired circuit elements in Figure 3, where, the X terminal parasitic is neglected for ease of analysis. The resistive and capacitive parasitic with suffix p1 and p2 refer to the Z1 and Z2 ports, respectively. The circuit analysis is performed to obtain the following oscillator parameters.
On the Effect of Operational Amplifier Gain-bandwidth Product on the Performance of Basic Building Blocks
Published in IETE Journal of Education, 2022
In this paper, we have reviewed several circuits using the finite gain-bandwidth product of the opamp. The students shall be taught about these to realize the importance of taking into account the non-idealities of the opamp in the design process. These ideas are applicable for circuits using other active devices, such as operational transconductance amplifiers and current mode devices such as a current conveyor (CC) and a current feedback operational amplifier (CFOA). Note that these devices have non-idealities such as finite input resistance, output resistance, output capacitance, current and voltage transfer gains, and internal poles. In this paper, we have not considered other non-idealities of the opamp viz., offset voltage and noise that affect the realizable dynamic range. Furthermore, a similar analysis needs to be carried out for high-order filters using several opamps by considering non-idealities of all opamps for realizing the desired performance.
A new low-voltage universal filter realisation using bulk-driven second generation current conveyors
Published in Australian Journal of Electrical and Electronics Engineering, 2019
Owing to the widespread usage of active filters in different fields of electronics and instrumentation systems like consumer electronics, military ordnance, telecommunications & radar, etc., a number of voltage-mode biquads have been proposed to date. Some of the most interesting topologies amongst those known in literature are Chang and Lee (1994), Özoguz and Gunes (1996), Horng, Tsai, and Lee (1996), Chang (1997), Horng et al. (1997), Liu and Lee (1997), Chang (1999), Horng (2004a), Horng (2004b). Second Generation Current Conveyor (CCII) is the key element reported for the integrated circuit implementation of these filters. Subsequently, CCII proposed by Sedra and Smith (1970) has emerged as the most recognised class of current-mode building blocks for analog filters. This stems from current conveyor inherent advantages of wide bandwidth, high slew rate, lower power consumption and simple circuitry (Soliman 1998) which enable it to rival its voltage-mode counterparts such as DDA, CFOA, FTFN, OTRA, CBDA, CDTA, etc. Various implementations for CCII have been proposed in the open literature (Wilson 1984; Cheng and Toumazou 1993; Elwan and Soliman 1996, 1997; Mahmoud, Elwan, and Soliman 2000). However more recently, the demand for small-sized and portable electronic devices has considerably grown which has diverted the interest of analog designers towards low-voltage low-power circuits. Hence, current conveyor-based filters are also under review.