Current-mode multifunction filter using opamp compensation poles

Meminductor is a nonlinear two-terminal element with storage energy and memory ability. To date, meminductor element is not available commercially as memristor and memcapacitor are. Therefore, it is of great significance to implement a meminductor emulator for breadboard experiment. In this paper, a flux-controlled floating/grounded meminductor emulator without a memristor is presented. It is built with commercially available off-the-shelf electronic devices. It consists of single operational transconductance amplifier (OTA), single multiplier, two second-generation current conveyors (CCIIs), single current-feedback operational amplifier (CFOA) and single operational amplifier. Using OTA device introduces an additional control parameter besides frequency and amplitude values of applied voltage to control the area of pinched hysteresis loop of meminductor. Mathematical model of proposed emulator circuit is given to describe the behavior of meminductor circuit. The breadboard experiment is performed using CA3080, AD844, AD633J and LM741 for OTA, CCII–CFOA, multiplier and operational amplifier, respectively. Simulation and experimental test results are given to verify the theoretical analyses. Frequency-dependent pinched hysteresis loop is maintained up to 5 kHz. The presented meminductor emulator tends to work as ordinary inductor for higher frequencies.

This paper presents a new programmable universal filter and quadrature oscillator based on single output operational transconductance amplifiers (OTAs). The proposed universal filter and quadrature oscillator can be achieved into single topology by programming using analog switches. When the circuit programs as a universal filter, it can realize low-pass, high-pass, band-pass, band-stop and all-pass filters with orthogonal and electronic controls of the natural frequency and the quality factor. When the circuit programs as a quadrature oscillator, it provides three-phase quadrature output signals which the condition of oscillation and the frequency of oscillation can be controlled orthogonally and electronically. The proposed structure can be realized based on single output OTAs which is easily implemented both commercially available integrated circuits as OTAs and complementary metal-oxide semiconductor and bipolar junction transistor OTA as IC forms. The performance of the proposed circuit is investigated by SPICE simulation using standard 0.18 μm CMOS process and experiment test using LM13600 discrete component integrated circuit as OTAs is used to confirm the workability of the new circuit.

Five new electronically tunable voltage-mode analog inverse active filters using single output operational transconductance amplifiers (OTAs) have been presented. The new proposed configurations can realize four different inverse filter structures using four/five OTAs along with two grounded capacitors. An exemplary OTA with 0.18 μm TSMC CMOS technology parameters has been used to corroborate the workability of these inverse filter topologies. PSPICE simulations with MATLAB evaluation results have been presented to validate the theoretical propositions. Temperature analysis and Monte-Carlo simulations have also been carried out to justify the robustness of the proposed inverse filters.

Current-mode electronically tunable biquadratic filters consisting of only CCCIIs and grounded capacitors

This paper proposes novel grounded and floating high order series and parallel immittance simulators using operational transconductance amplifiers (OTAs) and operational amplifiers (OAs) with a finite gain–bandwidth (GB) product. They are composed of active devices (OTAs and OAs) and resistances, and are suitable for monolithic implementation in either CMOS or bipolar technologies. They also realize both positive and negative high order immittances. The circuit characteristics can be electronically tuned by adjusting the transconductances of OTAs and the GB products of OAs. Any transfer functions are realizable using the proposed simulators. Two examples are shown, together with simulation results.

This article presents a current-mode multifunction filter performing completely standard function: low-pass, highpass, band-pass, band-reject and all-pass functions. The features of the circuit are that: the quality factor and pole frequency can be tuned by DC controlled bias current: the circuit description is very simple, it comprises only active elements, which are 2 current controlled current follower transconductance amplifiers (CCCFTAs) and 2 operational amplifiers (OAs). The proposed circuit is very suitable to further develop into an integrated circuit architecture. The PSpice simulation results are shown. The total power consumption is approximately 23.1mW at ±5V supply voltages. The given results agree well with the theoretical anticipation.

This paper presents a realization of voltage-mode and current-mode active-only biquad circuits with a two-integrator loop-structure. The circuits are constructed solely with operational amplifiers (OAs) and operational transconductance amplifiers (OTAs). The biquad circuits can realize the multiple circuit transfer functions, and the circuit parameters can be tuned orthogonally through adjusting the transconductance gains of the OTAs. Also, these biquad circuits enjoy very low sensitivities with respect to the circuit active elements. Some examples are given together with simulated results by PSPICE. The circuit configurations are very suitable for implementation on both bipolar and CMOS technologies.

This paper presents current-mode first-order allpass filter using three operational transconductance amplifiers (OTAs) and grounded capacitor. The use of grounded capacitor makes the circuit more suitable for integrated circuit implementation. The current gain and phase shift can be independently controlled with electronic method. The circuit has high output impedance which enables easy cascading in the current mode circuits. The PSpice simulation results are depicted. The given results agree well with the theoretical anticipation.

MOS-C realizations of the Kerwin–Huelsman–Newcomb (KHN) circuit using the commercially available Voltage Operational Amplifier (VOA) and the Current Feedback Operational Amplifier (CFOA) are reviewed in this paper. Additional MOS-C KHN realizations using the Operational Transresistance Amplifier (OTRA) and the Differential Current Voltage Conveyor (DCVC) are also included. MOS-C realizations of the KHN circuit using CMOS operational amplifier, CMOS current feedback operational amplifier and CMOS operational transresistance amplifier are also given.Spice simulation results using 0.18 CMOS technology model from MOSIS are included together with detailed comparison tables to demonstrate the differences between MOS-C KHN circuits using both of the commercially available active building blocks and CMOS integrated building blocks. A comparison with the Gm-C KHN circuit is also included.

Using unified representations for single current-feedback operational amplifier based immittance function simulators, new circuits can be systematically discovered. In this article a catalogue of t...

On combining the functions of negative-immittance conversion and positive-immittance inversion in a combined invertor/convertor stage of bridge configuration, a realisation of pure inductance has been achieved using a single operational amplifier of the differential-input type. On modifying the parameters, a grounded series LC branch may be obtained and used as a notch filter.

This paper presents the design and simulation results of a reconfigurable stimulator dedicated to multichannel neurobiology experiments. The proposed circuit employs a bipolar current stimulation and is based on only one operational amplifier that is dynamically switched among anodic and cathodic phases. The both multibiasing and current reusing techniques are used to save power consumption and area occupation of the stimulator. Additionally, the special attention was paid to increase the voltage compliance of the circuit what resulted in 91% of the voltage supply voltage compliance while keeping high output impedance in tens of mega-ohm range. The main current stimulator parameters, i.e. the current polarity and its value, duration and frequency of the current pulses, are controlled digitally. Each of the three current ranges, i.e. 2 μA, 10 μA, 200 μA, are controlled with 5-bit resolution. To keep the current pulses uniformity from channel to channel at a high level the MOS body biasing is used. The current stimulator is supplied from 3.3 V and is designed in CMOS 180 nm.

Current mode multifunction filter using two CDBAs

Differential amplifier is an analog component. which is used as an amplifier whenever a circuit contains more than one input. A differential amplifier is a basic primitive component in an operational amplifier. Differential amplifier contains three legs. In which two legs for the input signal to be amplified, the third leg used as output. The differential amplifier can be configured by bipolar technology or with Metal oxide semiconductor technology also. When the input non-inverted leg which acts as a comparator is applied as input, if any signal applied to invert leg of the differential amplifier it will be used as an amplifier. In this proposed article, the operational amplifier with high gain of 72dB is implemented, the Slew rate of 122 V/µs, Gain bandwidth product of 4.60 MHz Dual-stage operational amplifier will enhance the amplification in a better way when the single-stage amplifier is compared In this article, a dual-stage operational amplifier using CMOS 45nm Technology is implemented.

This paper presents a single loop fourth-order Discrete-Time Sigma-Delta Modulator (ΣΔM) using single Operational Amplifier (Op-Amp). Proposed ΣΔM utilises delay-based discrete-time integrators and an Op-Amp to implement all the integrators. Op-Amp reuse helps in saving power. A switched-capacitor based proposed design is simulated in standard 180 nm CMOS technology with an effective resolution of 12.04 bits. The proposed ΣΔM achieves a Signal to Noise Distortion Ratio (SNDR) of 74.24 dB with 78 dB of Dynamic Range (DR). An input signal of −4 dBFS magnitudes and 1.125 kHz of frequency is sampled at a sampling frequency of 320 kHz. The proposed circuit is designed for 10 kHz Bandwidth (BW) with Oversampling Ratio (OSR) of 16. The proposed modulator achieves Figure-of-Merit (FOM) of 158.68 dB/0.427 (pJ/conversion-step) with a total power consumption of 36 µW at 1.8 V supply voltage. The layout area of the proposed circuit is 134 µm ×134 µm.