Voltage tunable current MODE KHN filter based on current differencing transconductance amplifier (CDTA)

The era of SoC design has great dependency on CMOS circuits owing to its low power and high reliability which could contribute in the effective circuit designing. Here, a unique approach for the designing of voltage tunable current differencing transconductance amplifier (CDTA) is reported for the realization of Kerwin–Huelsman–Newcomb (KHN) filter. The proposed design has been simulated by using Cadence Virtuoso simulation tool with 0.18 [Formula: see text]m technology parameters. This design is based on input voltage-based gain and frequency of operation tuning approach. In this reported design of filter, cutoff frequency can be tailored by input voltage instead of input current. This relaxes the need for the iterative circuit modifications to work in a particular frequency range. Thus, the reported CDTA design is expected to be robust and offers higher design flexibility as there is now no need of iterative designing and calibration in this approach. This also exhibits retained area requirement as per the current state of the art for the KHN filters. Further, the performance of designed CDTA-based KHN filter has also been verified with the existing KHN filters.

Schmitt Trigger Circuits using Various Active Devices

A vast number of diverse analog circuit blocks have been arosed in the past few decades. A various active devices are Operational Amplifier (Op-Amp), Current Conveyor (CC), Operational Transconductance Amplifier (OTA), Differential Difference Current Conveyor (DDCC), Differential Difference Current Conveyor Transconductnace Amplifier (DDCCTA), Z-Copy Current Differencing Transconductance Amplifier (ZC-CDTA), Voltage Difference Transconductance Amplifier (VDTA) and so on. A review on Schmitt trigger circuits by using different active devices are presented in this paper since Schmitt trigger circuits are widely used in numerous applications such as in waveform generators, wave-shaping circuits, comparators, Bio-medical applications, analog processing systems, communication and instrumentation systems.

Design of Current Differencing Transconductance Amplifier using a Novel Approach of Transconductance Boosting for High Frequency Applications

This paper introduces a novel approach of transconductance boosting for current differencing transconductance amplifier (CDTA). Generally, the variation in the transconductance is achieved by changing the bias current and/or by increasing the aspect ratios of differential pair MOSFETs. These techniques of transconductance variations suffer from several serious drawbacks which include higher power dissipation, limited range of transconductance gain and lower input/output swing. The proposed approach of transconductance boosting overcomes these drawbacks at certain extent and also provides a high value of transconductance gain with acceptable range of bandwidth and power dissipation. It includes two different techniques to make it more effective for transconductance boosting. In the first technique, common source amplifiers have been used between gate and source terminals of the differential pair MOSFETs whereas in the second technique the concept of partial positive feedback is utilized. Using this approach, a new structure of CDTA namely cross-coupled common source current differencing transconductance amplifier I (CCCS-CDTA I) is proposed. To further improve the transconductance gain of CCCS-CDTA I, another structure CCCS-CDTA II is also proposed, in which the differential pair MOSFETs are replaced by two networks of “n” parallel MOSFETs having same aspect ratios. The proposed CCCS-CDTAs are simulated in Mentor Graphics Eldo simulator using TSMC 0.18[Formula: see text][Formula: see text]m process parameters. To confirm the performance of CCCS-CDTA II, physical layout and post-layout simulation results have been presented using Mentor Graphics Calibre tool. The advantages of proposed CCCS-CDTAs have also been discussed by realizing KHN filters and oscillators.

MOCCCDTA-based Current Mode Tunable Universal Biquad Filter for Bluetooth Applications

<p>In the last decade, there has been much effort to reduce the supply voltage of electronic circuits due to the demand for portable and battery-powered equipment. Since a low-voltage operating circuit becomes necessary, the current-mode technique is ideally suited for this purpose more than the voltage-mode one. In this paper, performance of multi output current controlled current differencing transconductance amplifier (MOCCCDTA) is evaluated using 180nm, 90nm and 45nm CMOS technology. It is found that the 45nm CMOS-based<br />MOCCCDTA provides highest frequency i.e. 33GHz. Further a Universal biquad filter has been designed using a single MOCCCDTA as an active element and two capacitors. Filter offers high frequency in GHz. Tunability of all the filter outputs with respect to a bias current has been analyzed. The tunability of the filter circuit for Bluetooth applications is also shown in this work. The performances of MOCCCDTA circuit and Universal biquad filter are illustrated by HSPICE. The simulation results are found to be in agreement with the theoretical predictions.</p>