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In this paper, a new universal current-mode filtering circuit with single input and multi-outputs based on OTAs (operational transconductance amplifiers) is proposed. The circuit just consists of two operational transconductance amplifiers, one current controlled current amplifier with multi-outputs (MO-CCCA), and two grounded capacitors. It can realize low-pass, band-pass, high-pass, band-stop, and all-pass filters simultaneously. Its quality factor and natural frequency can be tuned independently and the sensitivities are very low. Moreover, the non-ideal characteristic of the proposed filter is analysed and simulated by PSPICE. [ABSTRACT FROM AUTHOR]

In this paper, a new current differencing cascaded transconductance amplifier (CDCTA) is presented. The CDCTA circuit consists of a current differencing unit and n cascaded highly linear voltage-controlled transconductance amplifiers, and it possesses wide bandwidth and lineartunable feature. Based on this CDCTA, a systematic design method generating current-mode (CM) multiple-loop feedback filter is proposed. By altering the parameters of the design matrix, multiple nth-order CM all-pole low pass filters structures can be synthesized without changing internal circuit. The nth-order filters have low complexity and meet the requirement of no active and passive element matching conditions as adopting only a single CDCTA and n grounded capacitors. Furthermore, the frequency of the nth-order filters can be linearly tuned by the bias voltage. A fourth-order Butterworth filter is designed as an example, and its Cadence simulation results have good agreement with the theoretical analysis. [ABSTRACT FROM AUTHOR]

In this paper, a new fourth-order complex (polyphase) filter is realized with the leapfrog structure. The proposed filter is based on the first-order stage using multi-output current differencing transconductance amplifiers (MOCDTAs). The design procedures for the realization of the first-order stage and fourth-order leapfrog polyphase filter are presented. In the procedures, the signal flow diagrams are also presented. The proposed design using MOCDTA simplifies the circuit of the current-mode leapfrog complex filter, where there are no resistors and with minimum number of active components. Besides, its centre frequency and bandwidth could be electrically tunable independently. The centre frequency of the proposed filter could be adjusted from 20 to 80 MHz, and its bandwidth could be more than 20 MHz. With ± 1.25 V supply, two examples of the proposed filter are introduced. Their bandwidths are from 46.1 to 68.5 MHz and from 22.3 to 48.4 MHz, respectively. Their image rejection ratios could be more than 59 and 39 dB, respectively. Meanwhile, both the IIP3s are over 18 dBm. The theoretical results are demonstrated by using SPECTRE simulation in CHRT 0.18 μm standard complementary metal oxide semiconductor (CMOS) process. [ABSTRACT FROM PUBLISHER]

In this article, we propose a novel high-performance complementary metal oxide semiconductor (CMOS) current differencing transconductance amplifier (CDTA) with a transconductance gain (GM) that can be linearly tuned by a voltage. By using a high-speed, low-voltage, cascaded current mirror active resistance compensation technique, the proposed CDTA circuit exhibits wide frequency bandwidths, high current tracking precisions as well as large output impedances. The linear-tunableGMof the CDTA is designed with the use of linear composite metal oxide semiconductor field-effect transistor as basic cells in the circuit. Combining these two approaches, several design concerns are studied, including: impedance characteristic, tracking errors, offset and linearity and noise. The prototype chip with a 0.25 mm2area is fabricated in aGlobalFoundries’0.18 μmCMOS process. The simulated results and measured results with ±0.8 V DC supply voltages are presented, and show extremely wide bandwidths and wide linear tuning range. In addition, a fully differential band-pass filter for a high-speed system is also given as an example to confirm the high performance of the proposed circuit. [ABSTRACT FROM AUTHOR]

This letter describes a low-voltage low-power (LV-LP) 2.4-GHz mixer for Industrial, Scientific and Medical (ISM) band wireless applications. The approach is based on a two-stage amplifier, and the Gilbert switch stage is inserted between the two amplifier stages. The proposed amplifier-based mixer delivers a remarkable conversion gain of 13 dB with a local oscillator (LO) power of 7 dBm, while consuming only 1.05-mW DC power from a 0.8-V supply voltage. The input-referred third-order intercept point (IIP3) of the mixer is 3.82 dBm, and the chip area is only 0.429 mm2. The results indicate that this mixer is suitable for the low-voltage low-power applications. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, a novel $$\pm $$ 0.8V current differencing transconductance amplifier (CDTA) with programmable and tunable ability is proposed and analyzed. The digitally programmable CDTA is built around a lot of programmable current mirror arrays and three linear tunable transconductors, which contains separate analog and digital tuning feature. Moreover, a CDTA-based general sinusoidal signal generator circuit with two fixed-value capacitors and two grounded resistors is presented here. The generator circuit can be configured to perform the following signal modulation techniques: amplitude modulation, frequency modulation, amplitude shift keying, frequency shift keying, phase shift keying, and quadrature amplitude modulation. Cadence Virtuoso Analog Design Environment using GlobalFoundries' 0.18 um CMOS process is used to develop the generator circuit and verify the theory by the post-layout simulations. [ABSTRACT FROM AUTHOR]

This paper presents two new current differencing transconductance amplifiers (CDTAs)-based electronically tunable current-mode four-phase quadrature oscillators (QO). The proposed QOs consist of two CDTAs, one resistor and two grounded capacitors, respectively, which are suitable for monolithic integration. The condition of oscillation (CO) and frequency of oscillation (FO) can be independently controlled, and the FO can be electronically tunable by adjusting the bias current of the CDTA. Moreover, the QOs can provide four quadrature output currents at high-output-impedance nodes, which enable the QOs can be connected directly to the next stage without any impedance matching requirements. Cadence IC Design Tools 5.1.41 (Cadence Design Systems Inc., San Jose, CA) post-layout simulation results and experimental evidence are included to confirm the theory. [ABSTRACT FROM PUBLISHER]

In this paper, a new active device, current differencing cascaded transconductance amplifier (CDCTA), has been presented. The proposed CDCTA simplifies the design of the current-mode filter circuit considerably, especially the design of high-order filter. Moreover, a current-mode nth-order filter based on the CDCTA is proposed in the paper. The proposed circuit, which adopts only an active component and n grounded capacitors, contains minimal active component and passive one. It enjoys the simple configuration and is suitable for integrated circuit (IC) fabrication. PSpice simulations for current-mode third-order filter based on this structure have also been conducted, and the results are in good agreement with the theoretical analysis. The influences of the CDCTA non-idealities are also discussed. [ABSTRACT FROM AUTHOR]

Abstract: This letter presents a single CDTA (Current Differencing Transconductance Amplifier)-based current-mode quadrature oscillator (QO). The proposed circuit structure is very simple, which only consists of one CDTA, one resistor and two capacitors, and it is easy for monolithic integration. The oscillation frequency of the QO can be electronically controlled by the bias current of the CDTA. Moreover, the oscillator can provide two quadrature current outputs. PSPICE simulation results are provided to verify all the theoretical analysis. [Copyright &y& Elsevier]