A multiphase sinusoidal oscillator circuit is presented. The oscillator can produce N output-currents (N being even or odd) equally spaced in phase. The circuit uses translinear bipolar second-generation current-controlled conveyors, grounded capacitors and enjoys low active and passive sensitivities and independent current-control of the frequency of oscillation.

A new current-controlled multiphase sinusoidal oscillator using translinear current conveyors

A novel first order all-pass section using a single second generation current conveyor is given. In addition the circuit uses two resistors and only one capacitor. The circuit is also realized with a translinear conveyor. The latter circuit uses only one external resistor and a capacitor. The proposed circuits are verified using PSPICE with attractive results.

Simple first order all-pass section using a single CCII

Current conveyors based allpass filters and quadrature oscillators employing grounded capacitors and resistors

Three third-order quadrature oscillators are proposed. Outputs of two sinusoids with 90° phase difference are available in each quadrature oscillator circuit. The oscillation condition and oscillation frequency of each proposed quadrature oscillator are orthogonal controllable. All proposed circuits employ only grounded capacitors. The use of only grounded capacitors is ideal for integration. Experimental results are included to confirm the theoretical analysis.

Quadrature oscillators using CCIIs

The application of all-pass filters in the design of multiphase sinusoidal systems

Two circuits of Electronically Tunable Quadrature Oscillators (ETQOs) are given, which only use operational transconductance amplifiers (OTAs) and capacitors. In these circuits, a wide range of linear ƒo-tunability is present with bias voltage/current control of the OTAs. Outputs of equal amplitude, but in quadrature, are available in both the ETQOs. The circuits have a low component count, attractive sensitivities and suitability to implementation in monolithic MOS technology. Experimental results are included in support of the theory.

On transconductance-C quadrature oscillators

A simple circuit is given for realising an electronically tunable grounded capacitance multiplier. It employs two operational transconductance amplifiers (OTAs), an operational amplifier (OA) and a grounded capacitor (C). The circuit provides wide-range linear tuning of C-values through the bias control of OTAs. This multiplier is easily modified to realise a low-component floating C-multiplier. The circuits are MOS/Bi-MOS compatible and present definite advantages over the available multipliers. Experimental results are included.

Novel electronically tunable C-multipliers

Using a simple scheme, realisation of some novel multiphase sinusoidal oscillators (MPSOs) employing operational transconductance amplifiers (OTAs) as the active device are considered. These oscillators can provide n signals (n being odd) equal in amplitude as well as equally spaced in phase. Two practical OTA: RC three-phase oscillators have been realised and studied in detail. Their corresponding OTA-C realisations have also been obtained. Both the circuits enjoy low component count, low sensitivity performance and wide range electronic tunability. The OTA-C oscillators are highly suitable for monolithic implementation in MOS-form.

Tunable OTA-based multiphase sinusoidal oscillators

A simple scheme for realising four standard second-order voltage transfer functions, viz., low-pass, highpass, bandpass, and band-elimination is presented. It is implemented by using only operational transconductance amplifiers and capacitors to realise two universal biquadratic filters (UBFs), i.e. UBF-I and UBF-II. The UBF-I can also be converted into a sinusoidal oscillator by simply grounding a suitable node. The circuits have the attractive features of wide-range electronic tunability of its pole frequency, bandwidth and pole Q; these can also be programmed digitally. In addition, the filters enjoy excellent sensitivity performance and are suitable for monolithic MOS or Bi-MOS implementation. The effects of non-ideal buffer on the performance of the circuits are studied.

A simple realisation scheme for OTA-C universal biquadratic filter

A voltage mode two-phase quadrature oscillator using plus-type second generation current conveyors [CCIIs(+)] is realized by using a simple technique. The basic building block for this technique is a voltage mode non-inverting band-pass filter. The two-phase quadrature oscillator is then transformed into a four-phase quadrature oscillator by replacing the two CCIIs(+) by two dual output, current conveyors [DO-CCIIs]. The proposed circuits enjoy attractive features such as use of grounded passive components, independent frequency control, outputs of almost equal magnitude and low sensitivity figures. Both the oscillator circuits are designed and verified using PSPICE simulation.

Nigar Minhaj

Papers

On transconductance-C quadrature oscillators

Novel electronically tunable C-multipliers

Tunable OTA-based multiphase sinusoidal oscillators

A simple realisation scheme for OTA-C universal biquadratic filter

Current conveyor-based voltage-mode two-phase and four-phase quadrature oscillators