Usa Torteanchai

Current-mode third-order quadrature oscillator using VDTAs and grounded capacitors

This paper presents a novel electronically tunable current-mode third-order quadrature oscillator based on voltage differencing transconductance amplifier (VDTA). The proposed oscillator is constructed using two VDTAs and three grounded capacitors, which is advantageous for integrated circuit implementation. The circuit provides two current outputs with 90° phase difference from high output impedance terminals. The condition of oscillation and the frequency of oscillation can be electronically tuned by adjusting the bias current of the VDTAs. The sensitivity studies of the circuit have been carried out. PSPICE simulations with 0.35 μm TSMC CMOS process parameters are given to confirm the theoretical analysis.

A current-mode four-phase third-order quadrature oscillator using a MCCCFTA

This paper presents a new current-controlled current-mode third-order quadrature oscillator. The proposed circuit employs only one modified current-controlled current follower transconductance amplifier (MCCCFTA) and three grounded capacitors which is highly suitable for integrated circuit implementation. Also four quadrature current output terminals possess high impedance level which can be directly connected to the next stage without additional follower circuits. The condition of oscillation and the frequency of oscillation can be controlled orthogonally and electronically by adjusting the biasing currents of the MCCCCFTA. Simulation results verifying the theoretical analysis are included.

Tunable Current-Mode Quadrature Sinusoidal Oscillator Using CCCFTAs and Grounded Capacitors

This paper presents a new electronically tunable current-mode quadrature sinusoidal oscillator which employs only two current-controlled current follower transconductance amplifiers (CCCFTAs) and two grounded capacitors. The proposed oscillator offers the advantages of independent electronic control for setting the frequency of oscillation and the condition of oscillation, availability of two explicit quadrature current outputs, and low active and passive sensitivities. The outputs of the circuit possess high impedance level which is directly connected to the loads without buffer circuits. The use of grounded capacitors makes the proposed structure highly suitable for integrated circuit implementation. The workability of the proposed structure is verified by PSPICE simulations based on CMOS technology.

Current-tunable current-mode all-pass section using DDCC

This paper presents a new dual input current-mode first-order all-pass filter employing one differential difference current conveyor, one grounded capacitor and three grounded resistors. The use of grounded passive component makes the circuit suitable for integrated circuit implementation. The output terminals also have high impedance level which enables easy cascading in current-mode operation. The performances of the proposed circuit are simulated with PSPICE to confirm the present theory.

Electronically tunable multiple-input single-output voltage-mode multifunction filter employing simple CMOS OTAs

This paper describes a new electronically tunable four inputs and single output voltage-mode universal biquadratic filter based on simple CMOS operational transconductance amplifiers (OTAs) and grounded capacitors. The proposed filter provides low-pass, high-pass, band-pass, band-stop and all-pass voltage responses at a high impedance input terminal, which enable easy cascadability. The circuit parameters ωo and Q can be orthogonally set the circuit component. The parameter ωo also offers an electronic control by adjusting the transconductance gain of the OTA. For realizing all the filter responses, no critical component matching condition is required and all the parameter sensitivities are low. PSPICE simulation results are performed to confirm the theoretical analysis.

First-order allpass network using CFTA

This paper presents a new current-mode first-order allpass network. The network employs only one current follower transconductance amplifier, one capacitor and two resistors. Unlike previously works, the proposed network offers both non-inverting and inverting allpass transfer functions into one circuit. Moreover, the current gain of the network can be adjusted. The output terminal of the filter possesses high impedance level which is directly connected to the next stage without any buffer circuit. For realizing allpass transfer functions, no component-matching conditions are required. The simulation results are also used to verify the workability of the proposed network.

Single-Input Four-Output Voltage-Mode Universal Biquadratic Filter Employing Four OTAs and Two Grounded Capacitors

This paper presents a new single-input four-output electronically tunable voltage-mode biquadratic filter employing five operational transconductance amplifiers and two grounded capacitors. The proposed filter provides lowpass, band-pass, high-pass and band-stop voltage responses without changing the input and output terminal connections. The natural frequency and the quality factor can be set orthogonally by adjusting the circuit components. Also, the proposed filter provides high input impedance which can be directly connected in cascade to apply higher-order filters. No inverting-type input signals are required for the realizing of all the filter responses and all the active and passive sensitivities are low. Simulation results verifying the performances of the proposed circuit are also included.

Current-controlled quadrature oscillator using a new single ZC-CG-CCCCTA

This paper presents a new current-controlled current-mode quadrature oscillator using a single z-copy current gain current-controlled current conveyor transconductance amplifier (ZC-CG-CCCCTA) and two grounded capacitors, which is very suitable for integrated circuit implementation. The condition of oscillation and the frequency of oscillation can be controlled independently and electronically by adjusting the biasing currents of the ZC-CG-CCCCTA. The circuit also provides four quadrature current outputs with high impedance terminals. Simulation results are included to support the workability of the proposed circuit.

A CMOS log-antilog current multiplier/divider circuit using DDCC

This paper presents a new one-quadrant analog log-antilog multiplier/divider using only one differential different current conveyor and four diodes. The proposed circuit features low circuit complexity, very suitable for integrated circuit implementation and excellent temperature stability. Simulation results show performance of the circuit and confirm the validity of the proposed design technique.

Quadrature Oscillator Using Operational Transresistance Amplifiers

This paper presents a new quadrature oscillator using operational transresistance amplifiers (OTRAs). The use of OTRA as active elements which offers low parasitic parameters, high slew rate and high bandwidth independent of the gain, precision of oscillating frequency can be achieved. The oscillating frequency and oscillating condition of proposed oscillator can be independently controlled. Also output terminals are possessed low impedance level which can be directly connected to the load without any buffer circuits. Simulation results verifying the theoretical analysis are included to confirm proposed structure. From simulation results, it can be expressed that the simulation result is very agree well with theory.