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Tunable active grounded lossless and lossy inductance simulators with single grounded capacitor using VDBAs
(2022-04-01)
Tangsrirat, W.
;
Surakampontorn, W.
This study presents three active-C synthetic grounded inductance simulator circuits that realize tunable lossless and lossy series and parallel R-L type inductances. Each of these circuits employs two Voltage Differencing Buffered Amplifiers (VDBAs) as active components and a single grounded capacitor as a passive component. In all the proposed circuits, the simulated equivalent resistance and inductance values can be adjusted electronically through the transconductance gains of the VDBAs. They also do not require any critical component matching conditions and cancellation constraints. Details of non-ideal analysis including transfer errors of the VDBA has been analyzed. For circuit performance verification and comparison, some application examples are given together with computer simulation results by PSPICE program.
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Miniaturized microwave bandpass filter based on modified hairpin topology
(2010-12-01)
Srisathit, K.
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Tangjit, J.
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Surakampontorn, W.
This paper presents a microstrip hairpin bandpass filter (BPF) with simultaneously compact size and harmonic suppression. With the use of a square groove technique, the phase velocities between even- and odd-mode in parallel-coupled line segment are compensated. Two prototype filters based on the conventional hairpin and the proposed hairpin BPF are designed at the center frequency of 2.45 GHz with a fractional bandwidth of 20 percentages and fabricated on the microstrip structure. The proposed BPF exhibits the measured insertion loss of 1.2 dB at the centered frequency of 2.49 GHz, whereas the in-band return loss is kept below 12 dB from 2.21 to 2.7 GHz. Good agreements between the simulation and measurement can be obtained. © 2010 IEEE.
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Ladder-simulation elliptic bandpass active-RC filter structure employing identical resistors
(2009-08-21)
Mahattanakul, J.
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Khumsat, P.
;
Surakampontorn, W.
A novel structure of the ladder-based elliptic bandpass active-RC filter is presented. Unlike the previously reported elliptic bandpass active-RC filter, the proposed filter contains resistors with identical value and is therefore more suitable for integrated-circuit realisation. Also, according to the simulation results, the proposed elliptic bandpass filter performs better than the reciprocator-based active-RC filter, which employs identical resistors, in terms of noise, power and area. Additionally, the proposed filter structure was also found to be less sensitive than both of the aforementioned structures. © The Institution of Engineering and Technology 2009.
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Selection of the common-mode feedback network connection of fully differential Gm-C filters
(2009-02-10)
Mahattanakul, J.
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Khumsat, P.
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Surakampontorn, W.
It is well known that fully differential (FD) structures have many advantages over their single-ended counterparts. However, the main disadvantage of FD circuit is the potential instability caused by the inherent common-mode (CM) positive feedback loop. To solve such an instability problem, extra common-mode feedback (CMFB) and/or common-mode feedforward (CMFF) circuitries are often incorporated to stabilise the circuits. We present a systematic method for checking the stability condition and identifying the most suitable CMFB network connection for a particular FD Gm-C filter. It has been demonstrated that the CMFB network connection that provides highest CM rejection is not necessarily the conventional arrangement commonly used in FD Gm-C design. © The Institution of Engineering and Technology 2009.
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Single-resistance-controlled quadrature oscillator using current differencing buffered amplifiers
(2008-01-01)
Tangsrirat, W.
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Prasertsom, D.
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Piyatat, T.
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Surakampontorn, W.
A single-resistance-controlled quadrature oscillator circuit using current differencing buffered amplifiers (CDBAs) as active components is proposed. The proposed circuit is realised through the employment of two CDBAs, three resistors and two grounded capacitors. Outputs of two sinusoidal with 90 phase difference are available. The oscillation condition and the oscillation frequency of the proposed quadrature oscillator can be controlled independently by a single resistor. In comparison with the previously reported circuits, the proposed configuration considerably reduces the number of passive elements.
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Slew rate induced distortion in switched-resistor integrators
(2006-12-01)
Jiraseree-amornkun, A.
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Worapishet, A.
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Klumperink, E. A.M.
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Nauta, B.
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Surakampontorn, W.
OPAMP-RC integrators built with linear resistors and capacitors can achieve very high linearity. By means of a switched resistor, tuning of the RC time-constant is possible via the duty-cycle of the clock controlling the switched resistor. This paper analyzes the effect of OPAMP slew rate limitations on the distortion of a switched-resistor lossy OPAMP-RC integrator. We show via analysis and simulations that the use of two sets of switched resistors instead of one relaxes the OPAMP slew rate requirements, and reduces the resulting distortion significantly. ©2006 IEEE.
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Low-voltage NMOS-based current differencing buffered amplifier and its application to current-mode ladder filter design
(2006-11-01)
Tangsrirat, W.
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Klahan, K.
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Dumawipata, T.
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Surakampontorn, W.
An integratable circuit technique to realize a low-voltage current differencing buffered amplifier (CDBA) is introduced. The realization scheme is through the modification of a low-input resistance CCII+ and the proposed CDBA can operate with the minimum supply voltage of ±1.25∈V. In order that the signal path consists of only NMOS transistors, a negative current mirror using NMOS transistors is employed. With standard 0.5∈μm CMOS process parameters, PSPICE simulation results show that the proposed CDBA provides the terminal resistance of , , and the -3∈dB bandwidth of about 500∈MHz. Application examples employing the proposed CDBA as active elements in the leapfrog simulation of current-mode ladder filters are also included.
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Current-conveyor-based single-element-controlled and current-controlled sinusoidal oscillators
(2006-07-01)
Fongsamut, C.
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Anuntahirunrat, K.
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Kumwachara, K.
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Surakampontorn, W.
A new single-element-controlled sinusoidal oscillator circuit that incorporates two second generation current conveyors (CCIIs), two grounded capacitors and two resistors is presented and analysed. The circuit is beneficial to monolithic integrated circuit implementation by the use of grounded capacitors. In addition, a new current-controlled sinusoidal oscillator using only two second generation current controlled conveyors (CCCIIs) and two grounded capacitors can be achieved by replacing CCIIs and resistors series at X terminals with CCCIIs. The oscillators provide extremely low passive 0 -sensitivities and good frequency stability. Moreover, the oscillation frequencies of the CCII-based and the CCCII-based oscillators can be controlled, respectively, by a grounded resistor and by an external bias current. Experimental and SPICE simulation results that confirm the theoretical predictions are given.
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On the use of norator transformation in oscillator circuits
(2006-01-01)
Anuntahirunrat, K.
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Fongsamu, C.
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Surakampontorn, W.
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Fujii, N.
This paper presents a transformation of two norators for generating a class of current-conveyor-based oscillator circuits using two second generation current conveyor (CCIIs), two capacitors and two resistors. The generating method is through the representation of the nullator-norator equivalents of oscillator circuits. In addition, half of all circuits can be realized by employing RC:CR transformation. There are 5 additional circuits of this kind possible that have not been found in the published literature. © 2006 IEEE.
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On the use of nullator transformation in oscillator circuits
(2006-01-01)
Fongsamut, C.
;
Anuntahirunrat, K.
;
Surakampontorn, W.
;
Fujii, N.
A transformation of two nullators for generating a class of current-conveyor-based oscillator circuit that uses two second generation current conveyor (CCIIs), two capacitors and two resistors is proposed. The generating method is through the representation of the nullator-norator equivalents of oscillator circuits. In addition, half of all circuits can be realized by using RC:CR transformation. There are 6 additional circuits of this kind possible that have not been found in the published literature. © 2006 IEEE.

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