Electronically tunable higher-order quadrature oscillator employing CDBA

0.5-V Nano-Power Shadow Sinusoidal Oscillator Using Bulk-Driven Multiple-Input Operational Transconductance Amplifier

“…It can be expressed that the phase difference of signals V o 1 and V o 2 are 90 (π/2) degree and the magnitude is | g m 1 / C 1 |. It should be noted that the magnitude of V o 1 and V o 2 will be constant if the values of g m 1 and C 1 are not used for varying the frequency of oscillation, like in conventional quadrature oscillators [ 14 , 18 , 19 , 20 ].…”

“…As is well-known, sinusoidal oscillators require an amplitude stabilization mechanism, which can exploit circuit nonlinearities, limiting large-signal loop gain for larger amplitudes, or a special automatic gain control (AGC) circuit [ 14 , 18 , 21 ]. In the proposed solution, the amplitude stabilization mechanism is based on circuit nonlinearities, which provides sufficient quality for the generated waveforms, while it does not require an additional, relatively complex, circuitry to realize the AGC loop.…”

“…Sinusoidal oscillators are widely used in telecommunications, electronics, instrumentation, and control systems—for instance, providing a carrier signal for modulation in telecommunications and control systems [ 12 ], or acting as a waveform generator in electronic and instrument systems [ 13 ]. Therefore, a number of sinusoidal oscillators have been reported in literature that are based on various active devices such as the commercially-available ICs in [ 14 ], second-generation current conveyor (CCII) in [ 15 ], CFOA in [ 16 ], current differencing buffered amplifier (CDBA) in [ 17 , 18 ], current gain amplifier in [ 19 , 20 ], and voltage differencing inverting buffered amplifier (VDIBA) in [ 21 ]. The sinusoidal oscillators that enjoy electronic tuning capability are required because variant generated frequencies can be obtained without changing circuit components, also or the frequency error caused by temperature or process variations can be easily compensated.…”

Third‐order quadrature sinusoidal oscillators with fully uncoupled tuning laws using only two CFOAs and grounded capacitors

“…From Table 1, it is seen that none of the ABBs in the oscillators of the quoted references are available as commercial ICs yet. Moreover, the circuits compared in Table 1 suffer from one or more of the following drawbacks: (i) employment of all ungrounded capacitors, [37][38][39][40] (ii) nonavailability of independent control of CO and FO both, [37][38][39][40] and (iii) nonavailability of both outputs from low output impedance nodes. [24][25][26][27][28][29][30][31][32][33][34] A careful inspection of all the previously known CFOA-based TOQSO circuits of [20][21][22][23] reveals that they require three CFOAs and 4/5 resistors but do not provide fully uncoupled control of CO and FO.…”

A linear voltage controlled quadrature oscillator implementation using VCII

“…volt) [3]. Literature indicates that previous such oscillator designs with electronically tunable feature had been proposed in the recent literature [4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19], as depicted in Table I; wherein only a few exhibit linear tunability feature. The design in the previous such topologies use either some device bias-current (I b ) or device transconductance-parameter (g m ) or passive tune [20]; therefore the designs need additional current processing circuitry that attracts issues of thermal (V T ) and quiescent dissipation.…”