Current-mode Instrumentation Amplifier Research Articles

A Tunable Gain and Bandwidth Low-Noise Amplifier with 1.44 NEF for EMG and EOG Biopotential Signal

This paper presents a low-noise inverter-based current-mode instrumentation amplifier with tunable gain and bandwidth for electromyogram (EMG) and electrooculogram (EOG) biopotential signals, targeting low input noise while maintaining low power consumption. The gain tuning method is based on pseudo-resistors, whereas the bandwidth is tunable due to a varactor system that is controlled by the same control voltage that tunes the gain. The circuit was designed and manufactured using the 110 nm UMC CMOS technology node, occupying an area of 0.624 mm2. The circuit presents a functioning mode for each biopotential signal with different characteristics, for the EMG a gain of 34.7 dB and a bandwidth of 1412 Hz was measured, with an input referred noise of 1.407 μV which matches a noise efficiency factor of 1.44. The EOG mode achieves a 39.5 dB gain and a 22.4 Hz bandwidth while presenting an input-referred noise of 0.829 μV corresponding to a noise efficiency factor of 6.37. For both modes, the supply voltage is 1.2 V and the circuit consumes 1 μA.

A current mode instrumentation amplifier with high common-mode rejection ratio designed using a novel fully differential second-generation current conveyor

This study presents a high common-mode rejection ratio (CMRR), and high power-supply rejection ratio (PSRR) current-mode instrumentation amplifier (CMIA) to overcome the limitations of existing differential voltage second-generation current conveyors (DVCCII)-based CMIAs in achieving high CMRR. The design is based on a fully differential second-generation current conveyor block with a novel circuit design following by a current subtracting stage. The CMIA is designed and laid out in 130 nm CMOS technology operating under ± 1.2 V supply voltage in Cadence software. The post-layout simulation results show that the CMIA achieves low-frequency voltage and current CMRR- BW of 228.8 dB–10 kHz and 246 dB–10.6 kHz, respectively, with PSRR + /PSRR- of 108.2 dB/99.7 dB, power consumption of 507 µW, and a core area of 0.0015 mm2. The unique quality of the circuit is that, it does not need well-matched active blocks, but inherently improves CMRR, bandwidth, and PSRR; hence it gains an excellent choice for integration.

Electronically Tunable Current Mode Instrumentation Amplifier Employing Single DV-EXCCCII

In this paper, a new design of a current mode instrumentation amplifier (CMIA) is presented using a single differential voltage extra-X current controlled current conveyor (DV-EXCCCII) and a grounded resistor. Therefore, this circuit design is very simple and suitable for IC integration. The proposed circuit of instrumentation amplifier has high output impedance so it is easily cascadable with other current mode circuits without buffer requirement. Furthermore, the proposed circuit is electronically tunable with the bias current of the active element used. This circuit offers good frequency performance with wide differential gain and CMRR bandwidth. The non-idealities and parasitic effects of the proposed circuit are also investigated. To validate the proposed instrumentation amplifier, various simulations are performed using the CADENCE VIRTUOSO SPECTRE simulator using 0.18 µm CMOS technology parameters.

A Band-Pass Instrumentation Amplifier Based on a Differential Voltage Current Conveyor for Biomedical Signal Recording Applications

Recently, due to their abundant benefits, current-mode instrumentation amplifiers have received considerable attention in medical instrumentation and read-out circuit for biosensors. This paper is focused on the design of current-mode instrumentation amplifiers for portable, implantable, and wearable electrocardiography and electroencephalography applications. To this end, a CMOS differential voltage second-generation current conveyor (DVCCII) based on a linear transconductor is presented. A new band-pass instrumentation amplifier, based on the designed DVCCII, is also implemented in this paper. The concept of the proposed differential voltage current conveyor and instrumentation amplifier is validated numerically and their predicted performance is presented. The simulation results of the presented circuits were tested for 0.18 μm TSMC CMOS technology in a post layout simulation level using the Cadence Virtuoso tool with a ±0.9 V power supply, and demonstrated that the designed DVCCII has a wide dynamic range of ±400 mV and ±0.85 mA and a power consumption of 148 μW. The layout of the DVCCII circuit occupies a total area of 0.378 μm2. It is shown that the designed DVCCII benefits from good linearity over a wide range of input signals and provides a low input impedance at terminal X. Two versions of the proposed band-pass instrumentation amplifier using pseudo resistances were designed with different specifications for two different applications, namely for EEG and ECG signals. Numerical analyses of both designs show proper outputs and frequency responses by eliminating the undesired artifact and DC component of the EEG and ECG input signals.

A novel instrumentation amplifier with high tunable gain and CMRR forbiomedical applications

A new design of current mode instrumentation amplifier (CMIA) with tunable gain and low voltage operation capability is proposed in this paper, which is suitable for biomedical signals processing, especially in electrocardiogram (ECG). It consists of a new design of current differencing transconductance amplifier (CDTA) and dual z copy CDTA (DZC-CDTA). The gain of the proposed CMIA is controlled by a MOS-based tunable resistor. The main advantage of the proposed CMIA is its high gain that can be tuned over a significant range with the help of two resistances. The performance of the proposed instrumentation amplifier is evaluated through simulation results on Cadence Virtuoso using SCL 180 nm CMOS technology. From simulation results gain, common mode rejection ratio (CMRR), power supply rejection ratio (PSRR), %THD and -3 dB bandwidth of proposed instrumentation amplifier are obtained as 55.09?81.12 dB, 90.42-116.5 dB, 97.3 dB (+PSRR), 114.2 dB (- PSRR), 1.5% and 9.5-165 kHz, respectively. The performance of the proposed design is also examined against PVT variations. The performance of proposed CMIA is compared with other existing designs available in the literature, which clearly shows the competency of the design. The post layout simulation results confirm the on-chip implementation feasibility.

Single EX-CCCII based electronically tunable current mode instrumentation amplifier

The purpose of this study is to present a new design for an electronically tunable instrumentation amplifier. The current-mode design approach is used for the proposed circuit. The proposed current-mode instrumentation amplifier employs a single Extra-X Current Controlled Current Conveyor (EX-CCCII) and a grounded resistor. This circuit design is very simple and suitable for IC integration. Because of the circuit's high output impedance, it can be cascaded with other current-mode circuits without the need for a buffer. In addition, this circuit is electronically tunable with the bias current from EX-CCCII. The proposed instrumentation amplifier provides good frequency performance with a wide bandwidth for differential gain and CMRR. The effects of non-idealities of EX-CCCII and its parasitic elements are also analysed. To validate the proposed instrumentation amplifier, various simulations are performed with the CADENCE VIRTUOSO SPECTRE simulator using 0.18 µm CMOS technology parameters.

Optimal design of CMOS current mode instrumentation amplifier using bio-inspired method for biomedical applications

Analog integrated circuits for biomedical applications require good performance. This paper presents an instrumentation amplifier (IA) design based on three complementary metal oxide semiconductor (CMOS) conveyors with an active resistor. This circuit offers the possibility to control the gain by voltage and current. We have designed the IA to minimize the parasitic resistance (Rx) with large bandwidth and high common mode rejection ratio (CMRR) using the artificial bee colony algorithm (ABC). The topology is simulated using 0.35µm CMOS technology parameters. The optimization problem is represented by an objective function that will be implemented using MATLAB script. The results were approved by the simulation using the advanced design system (ADS) tool. The simulation results were compared to the characteristics of some other instrumentation amplifiers exsisting in the literature. The circuit has a higher CMRR than other topologies.

Increasing the Density of Field-Effect Heterotransistors in an Amplifier Flipped Voltage Follower Mirrors with Account of Miss-Match Induced Stress

In this paper, we introduce an approach to increase density of field-effect transistors framework current mode instrumentation amplifier flipped voltage follower mirrors. The approach we consider for manufacturing of the inverter in heterostructure with specific configuration. Several required areas of the heterostructure should be doped by diffusion or ion implantation. After that dopant and radiation defects should by annealed framework optimized scheme. We also consider an approach to decrease the value of mismatch-induced stress in the considered heterostructure. We also introduce an analytical approach to analyze mass and heat transport in heterostructures during manufacturing of integrated circuits with account mismatch-induced stress.

An Auto-Calibrated Resistive Measurement System With Low Noise Instrumentation ASIC

Most of the resistive sensors have a large baseline resistor and a relatively small incremental change in the resistor value due to the measurand. A half-bridge-based versatile $\Delta R/R_{s}$ measurement system for a wide range of resistive sensors is reported in this article. A four-phase auto-calibration-based differential and ratiometric operation is used to compensate for the baseline resistance of the sensor and the mismatches due to the non-ideal circuit parameters. A low-noise application-specific current generator and low noise, high CMRR current-mode instrumentation amplifier is designed and fabricated in UMC 180-nm technology. A prototype board of the $\Delta R/R_{s}$ measurement system is developed and tested. The experimental results show that the proposed system is able to detect even smaller ppm level of about 72 ppm of $\Delta R/R_{s}$ for the base resistor $R_{s}$ value as high as 0.5 $\text{M}\Omega $ with a relative error of less than ±1%. The effect of the parasitic capacitors on the sensor response is also tested experimentally. Finally, the proposed system is tested with an in-house fabricated displacement sensor.

Ultra low-power electronically tunable current-mode instrumentation amplifier for biomedical applications

In this paper, a new current-mode instrumentation amplifier with electronic tuning and low-voltage operation capabilities is presented. Simplicity is other important feature so that the whole circuit is composed of only 20 transistors. All the above have been achieved using MOS transistors biased in the sub-threshold region. The required current-controlled gain stage has been implemented using an appropriate translinear loop which is fed by the output of a current subtraction stage, realized through the employment of flipped voltage follower based current-mirrors. The performance of the presented amplifier is evaluated through simulation results, using the Cadence suite and MOS transistors models provided by the Austria Mikro Systeme 0.35μm CMOS process. The differential gain was 20–40dB, the Common-Mode Rejection Ratio (CMRR) was 44.4–48.9dB, achieved at power dissipation 72.75–386.1nW. The bandwidth was 7 kHz and the Total Harmonic Distortion (THD) was 2% for an input signal with amplitude equal to 550 pA. As an application example, the proposed current-mode instrumentation amplifier has been employed for removing the noise component in electrocardiogram signals.

High CMRR Current-Mode Instrumentation Amplifier for Low Voltage and Low Power Applications

This paper introduces a current-mode instrumentation amplifier circuit which employs one modified dual-X current conveyor transconductance amplifier only. The proposed instrumentation amplifier circuit is operated at ±0.75 V and consumes maximum power of 0.64 mW only, thus suitable to low voltage, low power applications. The proposed circuit also has the feature of cascadability as outputs are explicitly taken from high output impedance terminals. The differential mode gain of the proposed circuit is electronically tunable and less affected by the temperature variation. Additionally, differential mode gain is bandwidth independent as well. Moreover, the common mode rejection ratio of the circuit is 175 dB at lower frequencies and remains as high as 38 dB at 100 MHz. The non-ideal and parasitic analyses of proposed instrumentation amplifier are also discussed. The effects of threshold voltage variation of MOS transistors on differential mode gain are further examined. PSPICE simulations with 0.13 µm CMOS process parameters are performed to confirm the theoretical proposals. Furthermore, the proposed circuit is also tested experimentally via commercially available ICs (AD844 and LM13700).

A LP, Very High-CMRR, Wide-Bandwidth FDCCII-Based CMIA Adapted to Both Current and Voltage Inputs

This paper presents a novel current-mode instrumentation amplifier (CMIA) which is based on a fully differential second-generation current conveyor (FDCCII). This circuit is innovatively adapted to both types of input signals, thus becoming uniquely versatile. As another unique quality, neither does it need well-matched active blocks nor does it require matched resistors; but it can inherently improves common-mode rejection ratio (CMRR), bandwidth (BW), power and area consumption and hence becomes an excellent matchless choice for integration. Most favorably, its CMRR is enormously (100–105 dB) improved using a current subtracting stage. The proposed CMIA is designed using TSMC 0.18 um RF CMOS 2P6M Technology and supply voltages of ± 1 V. Its pre-layout and post-layout performances both plus Monte Carlo analysis are simulated using CADENCE. In pre-layout, it achieves voltage and current CMRR magnitude-BW of 224.9 dB–7.2 KH and 104 dB–0.94 KHz, respectively, differential voltage/current gain BW of 8.42 MHz/9.02 MHz, very low consumed power of 521.7 uW, output offset of 2.23 uV and area of 63.4 um \(\times \) 87 um. Exceptionally, post-layout plus Monte Carlo results are tightly close to pre-layout ones; altogether, it proves its well PVT insensitivity.

Electronically tunable high gain current-mode instrumentation amplifier

A new design for electronically tunable current mode (CM) instrumentation amplifier (IA) is presented in this paper. It employs Modified Z copy Current Differencing Transconductance Amplifier (MZC-CDTA) along with a resistor. The gain of the proposed CM IA is controlled by a single resistor and can theoretically approach infinite value. Electronic tuning feature is augmented by using a MOS based resistor. The functionality is verified through simulations on Cadence Virtuoso using TowerJazz’s 180 nm Technology Node and performance against PVT variations is also examined. Feasibility of on-chip implementation is confirmed by the post-layout simulations carried out.

A novel high CMRR trans-impedance instrumentation amplifier for biomedical applications

A compact high gain current mode instrumentation amplifier (IA) has been proposed for biomedical imaging applications. Conventional IAs rely on several matching resistors which occupies a lot of silicon area, the input and output common mode voltages are exactly same and the maximum applied signal amplitude is limited by internal node voltage swings. The present proposal eliminates the need for matching resistors by processing signals in the current mode. Hence input amplitudes are no longer limited by the voltage headroom and input and output common-mode voltages can be independent. An amplifier with a differential gain greater than 52 dB and a common mode rejection ratio greater than 120 dB has been implemented in 65 nm CMOS Technology and Post layout simulations were presented. The total circuit occupies 4500 μm2 silicon area and circuit consumes ~ 260 μA from 1.8 V power supply.

Cascadable current mode instrumentation amplifier

In this paper, a Current Mode Instrumentation Amplifier (CMIA) is presented. The proposed circuit employs two Extra X Current Controlled Current Conveyors (EX-CCCII) and a single grounded resistor. The circuit offers a wide differential-gain bandwidth, wide CMRR bandwidth, and electronically tunable differential gain. The circuit offers cascadibility feature with input impedance of 2.167 kΩ which is very small in comparison to the output impedance of 2.17 MΩ. Simultaneously, a Transresistance (TR) instrumentation amplifier is also obtained with the features of electronically tunable high differential gain and wide bandwidth. The effect of non-idealities of EX-CCCII on the circuit performance is also analysed. The validity of the proposed circuit is verified through PSPICE simulations using 0.25 µm parameters with a supply voltage of ±1.25 V. Also, the circuit is verified by experimental results.

Electronically tunable current-mode instrumentation amplifier with high CMRR and wide bandwidth

A current-mode instrumentation amplifier consists of only two current follower differential input transconductance amplifiers is proposed in this paper. The proposed circuit of instrumentation amplifier is realized without using any passive components. Thus, the proposed circuit structure is very simple and suitable to the integrated circuit technology. The input impedance is low and output impedance is high, therefore the proposed circuit is easily cascadable. The gain of the proposed instrumentation amplifier is electronically controllable. The proposed circuit also enjoys the features of high common mode rejection ratio, wide bandwidth and low power consumption. Additionally, performance of the proposed circuit is tested under process, supply voltage and temperature variations. Furthermore, another circuit of instrumentation amplifier, which is capable of providing higher differential mode gain is also shown. The non-ideal and parasitic studies are included. HSPICE simulations are performed to validate the proposed circuits of instrumentation amplifier.

A Novel Fully Differential Second Generation Current Conveyor and Its Application as a Very High CMRR Instrumentation Amplifier

This paper aims to introduce a novel Fully Differential second generation Current Conveyor (FDCCII) and its application to design a novel Low Power (LP), very high CMRR, and wide bandwidth (BW) Current Mode Instrumentation Amplifier (CMIA). In the proposed application, CMRR, as the most important feature, has been greatly improved by using both common mode feed forward (CMFF) and common mode feedback (CMFB) techniques, which are verified by a perfect circuit analysis. As another unique quality, it neither needs well-matched active blocks nor matched resistors but inherently improves CMRR, BW, and power consumption hence gains an excellent matchless choice for integration. The FDCCII has been designed using 0.18 um TSMC CMOS Technology with ±1.2 V supply voltages. The simulation of the proposed FDCCII and CMIA have been done in HSPICE LEVEL 49. Simulation results for the proposed CMIA are as follow: Voltage CMRR of 216 dB, voltage CMRR BW of 300 Hz. Intrinsic resistance of X-terminals is only 45 Ω and the power dissipation is 383.4 μW. Most favourably, it shows a constant differential voltage gain BW of 18.1 MHz for variable gains (here ranging from 0 dB to 45.7 dB for example) removing the bottleneck of constant gain-BW product of Voltage mode circuits.

Current and transimpedance mode instrumentation amplifier using a single new active component named CDTRA

In this study, both current and transimpedance mode instrumentation amplification operations are met through a new active building block proposal, namely Current DifferencingTransresistance Amplifier block, CDTRA. In order to regard CDTRA as an instrumentation amplifier (IA), two grounded passive resistors are needed. Passive resistors together with electronically tunable transresistance parameter of active block, rm, set versatility over gain tunability for instrumentation amplifier. Proposed active block is current input, current/voltage output design. It has low impedance input, high impedance for current output, and low impedance for voltage output respectively. Since this particular IA is based on CDTRA, then it inherits these electrical characteristics fully. Numerous SPICE simulations are performed through the paper to verify validity of the study. TSMC 0.18 µm CMOS technology parameters are utilized through simulations. Experimental work is performed for the proposed IA circuit.

A rail-to-rail constant-gm CCII for Instrumentation Amplifier applications

We here present a current mode Instrumentation Amplifier (IA) based on second generation current conveyor (CCII) with complete input/output dynamic range (rail-to-rail) and constant-gm characteristics. The IA operates at 1.5 V supply with 177 μW power consumption, high-loop gain (115 dB) and high CMRR (105 dB). The proposed IA has been implemented by using a standard AMS 0.35-μm CMOS technology. SPICE simulations are also reported.

A high-sensitive current-mode pressure/force detector based on piezoelectric polymer PVDF

This paper introduces new electronic sensor circuits based on the usage of a piezoelectric Polyvinylidene fluoride-PVDF pressure detector coupled with a current-mode instrumentation amplifier, Schmitt comparator, and only grounded resistors. Pressure/force is measured in terms of the charge generated by the PVDF element as a result of the direct piezoelectric effect. The experimental test results demonstrated that the dynamic pressure response, the sensitivity and linearity of the designed sensor were higher than the sensitivity and linearity of a traditional piezoelectric sensor. The sensitivity of the PVDF sensor was 0.08 mV/Pa. The detector is calibrated over a frequency range of 1 Hz–1 kHz. The proposed signal conditioning electronics offer a potential for future miniaturization in order to be integrated with different commercial devices, for detecting certain tiny activities including finger movements, robotics and smart electronic devices.