Current-mode operational transconductance amplifier-capacitor biquad filter structures based on Tarmy–Ghausi Active-RC filter and second-order digital all-pass filters
This paper describes the conception of the current follower transconductance amplifier (CFTA) with electronically and linearly current tunable. The newly modified element is realized based on the use of transconductance cells (Gms) as core circuits. The advantage of this element is that the current transfer ratios (iz/ipandix/iz) can be tuned electronically and linearly by adjusting external DC bias currents. The circuit is designed and analyzed in 0.35 μm TSMC CMOS technology. Simulation results for the circuit with ±1.25 V supply voltages show that it consumes only 0.43 mw quiescent power with 70 MHz bandwidth. As an application example, a current-mode KHN biquad filter is designed and simulated.
New circuit configurations for realizing bandpass and iowpass current-mode second-order filters are proposed. Each configuration uses a single first-generation current conveyor, a transconductance amplifier, three grounded capacitors, and two resistors at most. The parametersω0andω0/Q0of the bandpass and lowpass realizations are not interdependent and, therefore, single element control of the bandpass and lowpass characteristics is possible. Also, the feasibility of realizing a single element current-controlled sinusoidal oscillator is considered.
Operational Transconductance Amplifier (OTA) is an excellent current mode device suited very well for VLSI implementation. In this contribution we report realization of OTA using Silicon-On-Insulator (SOI) structure based MOSFETs and compared them to OTA designed with bulk MOSFET. SOI based OTA outperformed bulk MOSFET OTA giving close to 10 GHz improvement in high frequency f T . A band-pass filter was implemented with SOI based OTA with a center frequency of 7 GHz and a bandwidth of 480 kHz.
<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>
<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>
This paper presents a dual mode, single input multioutput (SIMO) biquad filter configuration using single voltage differencing transconductance amplifier (VDTA), three capacitors, and a grounded resistor. The proposed topology can be used to synthesize low pass (LP), high pass (HP), and band pass (BP) filter functions. It can be configured as voltage mode (VM) or current mode (CM) structure with appropriate input excitation choice. The angular frequency (ω0) of the proposed structure can be controlled independently of quality factor (Q0). Workability of the proposed biquad configuration is demonstrated through PSPICE simulations using 0.18 μm TSMC CMOS process parameters.
Gm-Realization of Controlled-Gain Current Follower Transconductance Amplifier