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ABSTRACT: This paper describes the design of a high-transconductance, wide-band, temperature-insensitive bipolar differential voltage-to-current
converter, the transconductance of which is determined by a chosen degeneration resistor. Detailed illustrations of current
and voltage traces are included to clarify circuit operation. Comparison with previously published designs shows that this
converter provides better linearity, with very low temperature sensitivity and excellent transconductance predictability.
Simulation results show that the proposed circuit, with a nominal transconductance of 5mS, has a Total Harmonic Distortion
(THD) better than −70dB at 10MHz, with a degeneration resistor of 400 Ω over an input voltage range of 350mV for supply
voltages of ±2.5V. The analysis and simulation comparisons are in good agreement.
KeywordsTransconductance-Voltage-to-current converter-Total harmonic distortion-Global feedback-Emitter degeneration
Circuits Systems and Signal Processing 04/2012; 29(6):1123-1140. · 0.82 Impact Factor
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ABSTRACT: The ion sensitive field effect transistor (ISFET) is a popular sensor in biomedical electronics and has been used to date mainly for relatively low speed applications, such as measurement of pH of common biomedical fluids. However, there is a growing interest in sensing rapidly changing ion activity for applications including chemical synapse and rapid DNA sequencing. In this reported work, it is demonstrated that the response time of the ISFET is sufficient for these applications. The results obtained are used to determine the factors that affect high speed chemical sensing with the ISFET.
Electronics Letters 06/2011; · 0.96 Impact Factor
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ABSTRACT: A novel circuit design technique is presented which improves gain-accuracy and linearity in differential amplifiers. The technique employs negative impedance compensation and results demonstrate a significant performance improvement in precision, lowering sensitivity, and wide dynamic range. A theoretical underpinning is given together with the results of a demonstrator differential input/output amplifier with gain of 12 dB. The simulation results show that, with the novel method, both the gain-accuracy and linearity can be improved greatly. Especially, the linearity improvement in IMD can get to more than 23 dB with a required gain. Copyright © 2009 John Wiley & Sons, Ltd.
International Journal of Circuit Theory and Applications 05/2009; 38(8):829 - 844. · 1.63 Impact Factor
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ABSTRACT: Design of differential amplifier with high gain accuracy and high linearity is presented in the paper. The amplifier design is based on the negative impedance compensation technique reported by the authors in [1]. A negative impedance with high precision, low sensitivity, wide input signal range and simple structure is used for the compensation of differential amplifier. Analysis and simulation results show that gain accuracy and linearity can be improved significantly with the negative impedance compensation.
Circuits and Systems for Communications, 2008. ICCSC 2008. 4th IEEE International Conference on; 06/2008
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ABSTRACT: This paper describes a highly linear and low- distortion, bipolar differential voltage-to-current converter (V-I) circuit that can be used for a number of applications, such as the transconductance stage for mixer circuits and gm-c filter circuits. This circuit is capable of providing a wider linear range of operation and lower total harmonic distortion compared with the conventional emitter-degenerated emitter-coupled differential pair due to the global feed-back technique used. Simulation results show that this circuit can provide 30dB improvement in total harmonic distortion over an operating range from -0.5V to +0.5V. This circuit uses a supply voltage of plusmn2.5V and an emitter degeneration resistor of 600 Omega.
Design and Technology of Integrated Systems in Nanoscale Era, 2008. DTIS 2008. 3rd International Conference on; 04/2008
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ABSTRACT: This paper describes the design of a DC voltage-to-current converter (V-I) which is unique in that, operating from a single positive supply rail, it produces an output current linearly related to an input voltage down to an input voltage of zero. Simulation results, presented for operation over a DC input range from zero to 100mV, are in very close agreement with those predicted by the theory presented.
Design and Technology of Integrated Systems in Nanoscale Era, 2008. DTIS 2008. 3rd International Conference on; 04/2008
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ABSTRACT: The operation of the conventional current feedback operational amplifier (CFOA) is reviewed and its performance parameters used as benchmarks in the development of a new input stage architecture that provides a common-mode rejection ratio (CMRR) improvement of some 45 dB and offset voltage less than 10 mV.
International Journal of Electronics. 12/2007; 94(12):1157-1170.
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ABSTRACT: A novel amplifier design technique based on the negative impedance compensation is presented for amplifiers with feedback. The theoretical and simulation results have shown that the proposed technique is very effective and can provide high gain accuracy and high linearity with relatively low open-loop gain amplifiers, hence the technique has a very good potential for high frequency applications.
Circuits and Systems, 2007. MWSCAS 2007. 50th Midwest Symposium on; 09/2007
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ABSTRACT: This paper considers two schemes in which negative feedback is applied to a conventional emitter-coupled differential voltage-to-current converter circuit in order to achieve lower distortion. Representative circuits for each of these schemes together with simulated results for a given value of emitter-degeneration resistor are presented. It is possible to achieve a reduction in total harmonic distortion (THD) exceeding 20dB, for a peak-to-peak differential input voltage of 500mV, over that possible without this feedback.
Circuits and Systems, 2007. MWSCAS 2007. 50th Midwest Symposium on; 09/2007
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ABSTRACT: The use of two complementary emitter-followers, in which the collector currents are held effectively constant by feedback action, facilitates the design of a differential voltage- current converter capable of producing lower output signal distortion. The proposed circuit provides an extended linear operating range, and total harmonic distortion (THD) 20 dB better than that compared with an emitter-degenerated long- tailed pair circuit. Simulation results show that the THD is better than -70 dB for differential input signals up to 0.5 V at a test frequency of 1 MHz and supply voltage of plusmn5 V.
Research in Microelectronics and Electronics Conference, 2007. PRIME 2007. Ph.D.; 08/2007
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ABSTRACT: This paper considers the trade-offs involved in the design of six new input stages intended to improve the performance of
a current feedback operational amplifier (CFOA), over that possible using an established input circuit configuration, with
respect to three major characteristics, viz, common mode rejection ratio (CMRR), offset voltage and slew-rate.
Analog Integrated Circuits and Signal Processing 02/2007; 50(3):163-183. · 0.59 Impact Factor
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ABSTRACT: A symmetrical BJT voltage-follower is presented which combines low harmonic distortion and high slew rate. Unlike conventional class-AB voltage-followers the proposed design provides large signal swing, some plusmn4.5 V on a plusmn5 V power supply, as well as large positive and negative output currents for driving capacitive loads, resulting in high slew-rate capability. The circuit exhibits gain flatness of 0.1 dB at 728 MHz with an inductive behaviour coming in at higher frequencies. The operational range is -20degC to +100degC with a power consumption of 55 mW at room temperature.
Electronics, Circuits and Systems, 2006. ICECS '06. 13th IEEE International Conference on; 01/2007
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ABSTRACT: The vertical stacking of two identical sub-circuits---improved versions of a bipolar transistor configuration proposed by Baxandall and Swallow---driven by dual output current mirrors, facilitates the design of a current generator producing a direct current of 1 mA with an incremental output resistance exceeding 200 GOmega.
Measurement Science & Technology - MEAS SCI TECHNOL. 01/2007; 18(1).
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ABSTRACT: This paper presents a novel voltage-follower, implemented in bipolar technology, designed for operation up to 250 MHz. It features high input and low output impedances, low total harmonic distortion (THD) and low offset-voltage
Communications, Circuits and Systems Proceedings, 2006 International Conference on; 07/2006
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ABSTRACT: A novel proportional to absolute temperature (PTAT) current converter is presented. Output current gain ratios in excess of 50 are possible without the use of an operational amplifier. Simulation measurements show an output temperature coefficient within 15 ppm/°C of the reference current over the temperature range of -40 to +85°C.
Electronics Letters 05/2006; · 0.96 Impact Factor
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ABSTRACT: A novel temperature-independent direct current converter, the subject of a patent application number GB051623.8, is presented. Conversion ratios from less than unity to in excess of 50 are possible. Simulation measurements show an output temperature coefficient as low as 16 ppm/°C over the temperature range -40 to +85°C.
Electronics Letters 12/2005; · 0.96 Impact Factor
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ABSTRACT: A novel drive circuit, useful for medical electronics, is capable of supplying a sample of human tissue, across which there should be zero direct voltage (dc), with a well-defined test current from a source having an output impedance exceeding 16 MOmega at 100 kHz.
Physiological Measurement 11/2005; 26(5):N21-7. · 1.68 Impact Factor
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ABSTRACT: This paper considers the trade-offs involved in the design of six new input stages intended to improve the performance of a current feedback operational amplifier (CFOA), over that possible using an established input circuit configuration, with respect to three major characteristics, viz, common mode rejection ratio (CMRR), offset voltage and skew rate.
Circuits and Systems, 2004. ISCAS '04. Proceedings of the 2004 International Symposium on; 06/2004
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ABSTRACT: This paper presents the designs of the two new CFOAs (current feedback op-amps), one employing a bootstrapping technique, the other a cascoding technique, that provide both high CMRR (common-mode rejection ratio) and slew rate. Moreover, the new CFOA designs exhibit a low DC offset voltage, high bandwidth, and improved gain accuracy, enabling them to be used in applications requiring variable closed-loop gains with constant bandwidth, such as in automatic-gain-control, video, graphics and multimedia applications.
Circuits and Systems, 2004. ISCAS '04. Proceedings of the 2004 International Symposium on; 06/2004
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ABSTRACT: A novel current-feedback operational amplifier, the input stage of which is based on the design and use in a repeated pattern of a current-transfer cell, exhibits performance characteristics superior to those obtained with an established input architecture: in particular, the common-mode rejection ratio (CMRR) is 105 dB, and the DC offset voltage less than 200 μV.
Electronics Letters 11/2003; · 0.96 Impact Factor
