Current-Mode Multiphase Sinusoidal Oscillator Using Current Differencing Transconductance Amplifiers

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.

Electronically Controllable Current-Mode Multiphase Sinusoidal Oscillator for Biomedical Tissue Measurement Systems

“…Several realizations of current-mode MSOs using different active building blocks are available in the literature. These include realizations using current follower (CF) [8], CCCII [9]- [11], CDTA [12]- [14], CDBA [15], CFOA [16], and CCCCTA [17] and CCCDTA [18], [19]. The CF-based MSO in [8] requires two current followers, one floating resistor, and one floating capacitor for each phase and thus the circuit is not suitable for monolithic integration.…”

“…The second reported circuit requires additional current amplifiers, which makes the circuit more complicated and increases its power consumption. CDTA-based current-mode MSOs in [12] is based on lossy integrators, where as the circuits in [13] and [14] contain CDTA-based allpass sections. They exhibit good performance in terms of electronic tunability, high-output impedances, and independent control of the oscillation frequency and the oscillation condition.…”

“…They exhibit good performance in terms of electronic tunability, high-output impedances, and independent control of the oscillation frequency and the oscillation condition. However, MSOs in [12], [13] require an additional current amplifier, which is implemented by two CDTAs. Moreover, the output currents of the MSO, utilizing the CDTA-based lossy integrators, are of different amplitudes.…”

All Pass Network Based MSO Using OTRA

“…For phase shifting either first-order low pass networks (LPNs) [5-7, 9-21, 24, 25] or first-order all pass networks (APNs) [2,8,22,23] are used. These reported structures provide either voltage [5][6][7][8][9][10][11][12][13][14][15][16] or current [2,[17][18][19][20][21][22][23][24] outputs.…”

“…Three topologies of OTRA based MSOs are proposed in [16] and are designed using LPNs. The structures proposed in [2,[17][18][19][20][21][22][23][24][25] provide current outputs which need to be converted back to voltage for circuits requiring voltage inputs, which would considerably increase the component count. A detailed comparison of these structures is given in Table 1 which suggests that OTRA based MSO is the most suitable choice for voltage output.…”