Saksit Summart

CCCIIs-Based First-Order All-Pass Filter and Quadrature Oscillators

This paper introduces a current-mode first-order all-pass filter (APF) and its application in quadrature oscillator (QO) based on CCCII. The proposed filter can provide inverting and noninverting all-pass functions with a same circuit topology, it uses two CCCIIs and one grounded capacitor. Moreover, the first-order all-pass filter was applied in current-mode sinusoidal quadrature oscillators with the design based on block diagrams. The introduced oscillators can provide four phase-quadrature signals which independently control the condition of oscillation (CO) and frequency of oscillation (FO). The proposed oscillators consist of three CCCIIs and two grounded capacitors. The proposed APF and QOs have high output impedance which can directly drive load without additional current buffer. In addition, they use only grounded capacitors which are very appropriate to future development into an integrated circuit. The results of PSPICE simulation program correspond to the theoretical analysis.

Second Order Current-mode Quadrature Oscillators Using OTAs

This article presents new current-mode quadrature oscillator circuits using OTA which are designed from block diagram. The proposed circuits consist of three OTAs and two grounded capacitors. The circuits have high output impedance appropriate for cascade connection application in current mode technique which is capable to directly drive load. The oscillators use only grounded capacitor which is very appropriate for further development into an integrated circuit. In addition, the condition of oscillation can be adjusted orthogonally from the frequency of oscillation. The results of PSPICE simulation program are corresponding to the theoretical analysis.

DUAL-OUTPUT CURRENT DIFFERENCING TRANSCONDUCTANCE AMPLIFIERS-BASED CURRENT-MODE SINUSOIDAL QUADRATURE OSCILLATORS

This paper presents three current-mode quadrature oscillator (QO) circuits based on dual-output current differencing transconductance amplifier (DO-CDTA) which is designed from block diagram. The proposed circuits consist of two DO-CDTAs and two grounded capacitors. The circuits can provide two sinusoidal output currents with 90° phase difference. The condition of oscillation (CO) can be adjusted independently from the frequency of oscillation (FO) by adjusting the bias currents of the DO-CDTA. The proposed circuits have high output impedance appropriate for cascade connection application in current mode which is capable to directly drive load. The circuits use only grounded capacitors without any external resistor which is very appropriate for further development into an integrated circuit. Moreover, the oscillator circuits can also adjust amplitude of the output signal. The results of PSPICE simulation program are corresponding to the theoretical analysis.

Curved double-layer strip folded dipole antenna for WBAN applications

This paper presents an optimal design of strip folded dipole antenna with a stacking technique to stabilize the resonance frequency. The designed double-layer strip folded dipole antenna worked well with the cylindrically curved surface on the human body. While being bent, the antenna will change the extended length in each layer within the stacking flexible copper-clad laminate. In this case, the properties of the antenna will be automatically adjusted. However, the extended length can occur at the contact point in each layer. So, we can choose between two points and four points by selecting different types of the designs. This reason, the performance of the extended length can be added by two and four when being compared to the previous multilayer design and the total layer of the new antenna was only two. The extended length of the antenna resulted in making antenna resonance frequency improvement become more stable. The contribution of proposed antenna was used only two layers of flexible copper-clad laminate that reduces a number of antennas layers with a folded dipole antenna, which causes the designed less complicated, and the flexibility is advantageous for WBAN applications. The double-layer strip folded dipole antenna is designed for 2.45GHz WBAN application.

Four phase current-mode sinusoidal quadrature oscillator based on CCCIIs

This article presents a current-mode four phase quadrature oscillator with orthogonal control for condition of oscillation (CO) and frequency of oscillation (FO) based on CCCII. The proposed circuit consists of 3 CCCIIs and 2 grounded capacitors. The proposed circuit can generate four sinusoidal output current terminals with 90o phase difference. It also provides high output impedances that make the circuit can drive load without additional current buffers. The CO and FO can be controlled electronically by adjusting the bias current. The proposed circuit uses only grounded capacitors without any external resistor which is beneficial from the point of view of integrated circuit fabrication. The simulation results by PSpice program are shown corresponding with the theoretical analysis.

CDTAs Based Current-Mode Universal Biquad Filters with Orthogonal Control of Quality Factor and Pole Frequency

This article presents current-mode universal biquad filters based on CDTAs. The filter circuits using four CDTAs and two grounded capacitors which are able to provide low-pass, high-pass, band-pass, band-reject and all-pass functions. The pole frequency can be orthogonally controlled from quality factor and the circuits have high output impedance appropriate for cascade connection application in current mode which is capable to directly drive load. This qualification is very appropriate for further development into an integrated circuit. The results of PSPICE simulation program are corresponding to the theoretical analysis.