On transconductance-C quadrature oscillators

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 ƒ o -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.