AC amplifiers with ultra-low corner frequency by using bootstrapping

A novel architecture for an AC (i.e. high-pass) amplifier is proposed allowing a drastic reduction of the cutoff frequency to the sub-Hertz range. It builds upon the classic AC configuration with a high gain amplifier and a parallel RC circuit in the feedback loop, by increasing the feedback resistance through bootstrapping. Resistance multiplying factors higher than four orders of magnitude are easily achievable. The basic principle can be applied to several practical implementations, though in this letter it is demonstrate with measurement results of an op-amp based discrete implementation.This work was financially supported by the following grants from the Spanish Research Agency: TEC2016-80396-C2-1-R and PID2019-107258RB-C32 (AEI/FEDER). M.Martincorena Arraiza was funded by the Ministry of Universities under grant BES-2017-080418

Minimal realisation for single resistor controlled sinusoidaloscillator using single CCII

For original paper by Celma et al., see ibid. vol.28, no.5, p.443-4 (1992). The commentator indicates that this oscillator had already been published in the literature. Moreover, another oscillator circuit which has similar properties is presented. The authors had presented a truly canonic second-order RC sinusoidal oscillator using a single second generation current conveyor. The proposed structure uses two capacitors and only three resistors. The condition and the frequency of oscillation can be adjusted independently using two control resistors. The authors reply that they regret the unintentional omission of two related References by Abuelma'atti in their Letter and appreciate his Comment. The oscillator had been independently obtained by the authors from an original synthesis procedure. They recognise that they were not aware that the oscillator in question had been reported in the literature. In any case, the aim of their work was to demonstrate the characteristics and the performance of a practical implementation of a CCII SRCO rather than claim the novelty of a circui

Symbolic analysis of analog circuits containing voltage mirrors

7 páginas, 7 figuras, 2 tablas, 4 imágenes.-- Open Access: This article is distributed under the terms of the Creative Commons Attribution Noncommercial License.The pathological elements voltage mirror (VM) and current mirror (CM) have shown advantages in analog behavioral modeling and circuit synthesis, where many nullor-mirror equivalences have been explored to design and to transform voltage-mode circuits to current-mode ones and viceversa. However, both the VM and CM have not equivalents to perform automatic symbolic circuit analysis. In this manner, we introduce nullor-equivalents for these pathological elements allowing to include parasitics and to perform only symbolic nodal analysis. The nullor-equivalent of the CM is extended to provide multiple-outpus (MO-CM). Finally, two active filters containing VMs, CMs and MO-CMs are analysed to show the usefulness of the models.This work is supported by: UC-MEXUS and CONACyT under grants CN-09-310 and 48396-Y; by Promep-Mexico under grant UATLX-PTC-088; by Consejeria de Innovacion, Ciencia y Empresa, Junta de Andalucia-Spain TIC-2532; and by the JAE-Doc program of CSIC co-funded by FSE, Spain.Peer reviewe