Search

This paper examines the closed-loop characteristics of the basic Current-Feedback Operational Amplifier (CFOA), and in particular, the dynamic response. Additionally, it also examines the design and advantages of the CFOA regarding its ability to provide a significantly constant closed-loop bandwidth for closed-loop voltage gain. Secondly, the almost limitless slew–rate provided by the class AB input stage that makes it superior to the voltage-mode operational amplifier (VOA) counterpart. Additionally, this paper also concerns the definitions and measurements of the terminal parameters of the CFOA, regarded as a ‘black box’. It does not deal with the way that these parameters are related to the properties of the active passive and active components of a particular circuit configuration. Simulation is used in terminal parameter determination: this brings with it the facility of using test conditions that would not normally prevail in a laboratory test on silicon implementations of the CFOAs. Thus, we can apply 1mA and 1mV test signals from, respectively, infinite and zero source impedances that range in frequency from d.c to some tens of GHz. Also, we assume the existence of resistors with identical Ohmic value and very high value ideal capacitors. Where appropriate, practical test methods are referred to physical laboratory prototypes. [ABSTRACT FROM AUTHOR]

This paper proposes a circuit configuration for realizing current-mode lowpass and bandpass filters using the operational amplifier (op.-amp.) pole. The circuit simultaneously realizes lowpass and bandpass transfer functions using an op.amp., three resistors and a capacitor. The effects of the parastic poles (i.e. second and third poles) of the op.-amp. on the gain of a lowpass filter are also presented. Since the circuit uses the op.-amp. pole, it is suitable for high frequency operation. This paper proposes a circuit configuration for realizing current-mode lowpass and bandpass filters using the operational amplifier (op.-amp.) pole. The circuit simultaneously realizes lowpass and bandpass transfer functions using an op.amp., three resistors and a capacitor. The effects of the parastic poles (i.e. second and third poles) of the op.-amp. on the gain of a lowpass filter are also presented. Since the circuit uses the op.-amp. pole, it is suitable for high frequency operation. [ABSTRACT FROM AUTHOR]

In this paper, an active-only grounded lossless inductance simulator operating in current-mode is presented. The circuit uses only a current operational amplifier (COA) and an operational transconductance amplifier (OTA). The novelty of the proposed circuit is that it uses a COA instead of a voltage operational amplifier (VOA) to take the wider frequency operation advantage of the current-mode approach. The simulation results obtained through SPICE with 0.5 μm standard CMOS technology verify that the designed circuit can be operated up to 30 MHz, which is much higher than the operation frequency of previously reported inductance simulators utilising VOAs. The inductance value of the presented circuit can be adjusted electronically between 3.9 μH and 37 μH via the biasing current of the OTA. A parallel resonance circuit application is also given validating the operation of the proposed inductance simulator. [ABSTRACT FROM AUTHOR]

In this paper, a new trans-impedance mode single-input–three-output (SITO) filter using opamp compensation poles is presented. The proposed circuit is composed of two internally compensated operational amplifiers (OAs) and four single-output operational transconductance amplifiers (OTAs), without using any external passive elements. The proposed multifunction filter can realize lowpass, bandpass and highpass responses simultaneously all at low output impedances. No matching condition is required. The circuit is suitable for monolithic implementation either with complementary metal oxide semiconductor (CMOS) or bipolar technologies. All of active sensitivities are low. The performance of the circuit is tested using SPICE simulation program. [ABSTRACT FROM AUTHOR]

This paper presents a realization of a current-mode active-only biquad with a two-integrator loop structure. The proposed circuit is constructed solely with operational amplifiers (OAs) and operational transconductance amplifiers (OTAs). The circuit can realize low-pass, band-pass, high-pass, band-stop and all-pass transfer functions, and the circuit characteristics can be electronically tuned by adjusting the transconductance gains of the OTAs. An example is given together with simulated results by PSPICE. The circuit configuration is very suitable for implementation in both bipolar and CMOS technologies. [ABSTRACT FROM AUTHOR]

In this paper we propose an active circuit consisting of two capacitive double-layer uniformly distributed RC lines and an operational amplifier, and present conditions under which the circuit works as the low-pass filter. Furthermore, we present a method for designing the low-pass filter and give a design example where simulation results are included. [ABSTRACT FROM AUTHOR]

This paper presents a realization of a voltage-mode active-only biquad using operational amplifiers (OAs) and operational transconductance amplifiers (OTAs). The circuit configuration is obtained from a second-order integrator loop structure with lossless and lossy integrators. The proposed circuit can realize low-pass, band-pass, high-pass, band-stop and all-pass transfer functions by a suitable choice of input and output terminals. The circuit characteristics can be electronically tuned through adjustment of the transconductance gains of the OTAs. An example is given, together with simulated results by PSPICE. The circuit configuration is very suitable for implementation in both bipolar and CMOS technologies. [ABSTRACT FROM AUTHOR]

This paper presents a realization of a voltage-mode active-only biquadratic circuit. The proposed circuit is constructed employing solely operational amplifiers and operational transconductance amplifiers (OTAs). The circuit configuration is obtained from a second-order structure with two integrator loops. The circuit can realize low-pass, band-pass, high-pass, band-stop, low-pass notch, high-pass notch and all-pass transfer functions by suitably choosing the input and output terminals, and the circuit characteristics can be electronically tuned through adjusting the transconductance gains of OTAs. Some examples are given together with simulated results by PSPICE. The circuit configuration is very suitable for implementation in both bipolar or CMOS technologies. [ABSTRACT FROM AUTHOR]