Teerasilapa Dumawipata

Low-voltage NMOS-based current differencing buffered amplifier and its application to current-mode ladder filter design

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.

Cascadable current-mode multifunction filter with two inputs and three outputs using CDTAs

The current-controlled current-mode universal filter with two inputs and three outputs using current differencing transconductance amplifiers (CDTAs) as active components is presented. The proposed circuit configuration consisting of only three CDTAs and two grounded capacitors exhibits low-input and high-output impedances, which is advantageous from an integration point of view and is important for easy cascading in the current-mode operations. By properly connecting the input and output terminals, the filter can simultaneously realize all the standard filter functions, namely lowpass (LP), bandpass (BP), highpass (HP), bandstop (BS) and allpass (AP), without any component matching conditions. The natural angular frequency (omegao) and the bandwidth (omegao/Q) of the proposed filters can be electronically controlled, thanks to the tunability properties of the CDTAs. All the passive and active sensitivities are low. SPICE simulation results are included to confirm the theory.

Simulation of electronically tunable lossless floating inductor using current-controlled differential current voltage conveyors

The circuit configuration for the bipolar realization of a current-controlled differential current voltage conveyor (CCDCVC) is introduced. A new current-controlled lossless floating inductance simulator using only three of the proposed CCDCVCs and a grounded capacitor is also proposed; its equivalent inductance can be tuned by means of the bias current of the CCDCVC. Without the employment of any external passive resistors, the proposed inductance simulation circuit is particularly attractive for integrated circuit (IC) implementation. PSPICE simulations of the proposed circuits give results that agree well with the theoretical analysis.

Current-mode Universal Filter with Four Inputs and One Output using CDTAs

A current-controlled multiple-input single-output current-mode universal filter employing current differencing transconductance amplifiers (CDTAs) as active elements is described. The proposed circuit offers the following attractive features: employment the minimum number of active and passive components; simultaneous realization of all the standard filtering functions; independent current-control of the parameters omega0 and omega0/Q; no requirement of component matching conditions; employment of only two grounded passive capacitors which is suitable for integrated circuit (IC) implementation; and low passive and active sensitivities

TISO Cascadable Current-Mode Multifunction Filter Employing Current Differencing Transconductance Amplifiers

A circuit realization of a current-mode multifunction filter with three inputs and one output employing current differencing transconductance amplifiers (CDTAs) as active components is presented in this paper. The proposed circuit employs only three CDTAs and two grounded capacitors and exhibit low-input and high-output impedances, which is very suitable for an integrated circuit implementation and easy cascading in the current-mode operations. By properly selecting the input current terminals, the proposed filter can realize all standard biquadratic functions, i.e., the lowpass (LP), highpass (HP), bandpass (BP), bandstop (BS) and allpass (AP) filtering functions without changing the circuit configuration. The natural frequency (omega0 ) and the bandwidth (omega0/Q) of the proposed filter can electronically be tuned by controlling the bias current of the CDTA. The filter also provides the low active and passive sensitivities. Simulation results with PSPICE are used to confirm the presented theory

Design of active-only highpass and bandpass leapfrog filters using multi-current-output differentiators

This paper presents an alternative approach for realizing active-only current-mode leapfrog ladder filters using a multi-current-output differentiator. A novel multi-output differentiator, which is only composed of internally compensated type operational amplifiers (OA) and operational transconductance amplifiers (OTAs), is first proposed. The proposed design procedures of the active-only current-mode highpass and bandpass leapfrog ladder filters, employing only OTAs and multi-output differentiators without external passive elements, are then presented. A property of this approach is the possibility of tuning the current transfer function by the external controlled transconductances. PSPICE simulation results verifying theoretical predictions are included.

CFOA-based single resistance controlled quadrature oscillator

This paper presents a new single-resistance-controlled (SRC) sinusoidal quadrature oscillator with reduce number of passive elements using only two current-feedback operational amplifiers (CFOAs). The proposed oscillator configuration comprising two CFOAs, three resistors and two capacitors provides two sinusoidal voltage outputs in phase quadrature. The circuit has the advantage of independent control of the condition of oscillation and the oscillation frequency through a single resistor. In addition, both proposed circuit configurations have good active and passive sensitivity performance. PSPICE simulation results based on commercially available AD844-type CFOAs are also included, showing the excellent performance of the proposed oscillator configuration.

Low-Voltage Current Differencing Buffered Amplifier Using Only NMOS Transistors

A circuit realization of a current differencing buffered amplifier (CDBA) in low-voltage operation is presented. The scheme is through the modification of a low-input resistance CCII+ and the proposed CDBA can operate with the minimum supply voltage of plusmn1.25 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-mum CMOS process parameters, PSPICE simulation results show that the proposed CDBA provides the terminal resistances of rn = rp = rw= 13 Omega, rz = 290 kOmega, and f-3db cong 3 500 MHz.

A realization of current-mode biquadratic filters using multiple-output FTFNs

A configuration for realizing a current-mode second-order multifunctional filter using four-terminal floating nullors (FTFNs) is presented in this paper. The proposed filter consists of three multiple-output FTFNs and passive grounded elements. The circuit can simultaneously realize the highpass, bandpass and lowpass current transfer functions from the same configuration, orthogonal control of the natural angular frequency /spl omega//sub 0/ and the quality factor Q and low active and passive sensitivities. PSPICE simulation results are employed to verify the circuit performance.

Cascadable Current-Controlled Current-Mode Multifunction Filter Using CDTAs

The cascadable current-controlled current-mode multifunction filter with three inputs and one output using current differencing transconductance amplifiers (CDTAs) as active components is presented. The proposed configuration comprising only three CDTAs and two grounded capacitors provides low-input and high-output impedances, which is advantageous from an integration point of view and is important for easy cascading in the current-mode operations. By properly joining the input and output terminals, the circuit can simultaneously realize all the standard filter functions, namely lowpass (LP), bandpass (BP), highpass (HP), bandstop (BS) and allpass (AP), without any component matching conditions. The natural angular frequency (omegao) and the bandwidth (omegao/IQ) of the proposed filters can be electronically controlled, thanks to the tunability properties of the CDTAs. All the passive and active sensitivities are low. SPICE simulation results are included to confirm the theory.