No abstract

This paper describes a simple current-controlled current-mode multiphase sinusoidal oscillator based on current differencing transconductance amplifiers (CDTAs) as active components. The proposed oscillator circuit, which employs only one CDTA and one grounded capacitor for each phase, can generate arbitrary n current-output signals (n being even or odd) equally spaced in phase, all at high output impedance terminals. The oscillation condition and the oscillation frequency can be controlled electronically and independently through the bias current of the CDTA. The oscillator has low-component count, low-sensitivity performance, and is highly suitable for monolithic implementation. PSPICE simulation results are given to confirm the operation of the proposed oscillator.

The realization of a resistorless current-mode firstorder allpass filter using current differencing transconductance amplifiers (CDTAs) as active components is presented. The proposed filter employs only two CDTAs and one virtually grounded capacitor, which its phase shift can be electronically adjusted by varying the bias current of the CDTA. The circuit also exhibits high-output impedance, which is easy cascading in the current-mode operation. As application example, the currentmode biquad filter based on the proposed CDTA-based allpass sections is also presented. PSPICE simulation results of the proposed circuit and its application are given to confirm the theoretical analysis.

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 (c),) and the bandwidth (JoIQ) 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.

A circuit technique for realizing a current-mode second-order notch filter using CDTA-based first order allpass sections is presented in this paper. The proposed circuit employs only four CDTAs and two virtually grounded capacitors, and exhibit low-input and high-output impedances, which is suitable for cascading in current-mode operation. The circuit also has low passive and active sensitivities. Moreover, if the active and passive component values are properly chosen, the circuit permits the realization of second-order allpass current response. PSPICE simulation results are used to verify the theoretical analysis.

No abstract