Cell dielectric impedance spectroscopy is a novel technique for diagnosis of biological tissues, by characterizing properties of the matter such as permittivity and conductivity. These properties can be measured by the phase difference between the voltage and the current signals applied to the biological material under test. The impedance of the biological tissue can be measured by means of a quadrature signal generator, which should be capable to perform a wide tuning frequency in order to obtain an insightful description of the biological material. This work proposes the design of a wide tuning range quadrature VCO, by using voltage controlled ring-oscillators as injection-frequency dividers by 2, 3 and 4 of an injected signal. In this work is also discussed the feasibility of designing the corresponding injection signal source by an LC tank based differential VCO. The complete circuit is designed in IHP SG 130- nm technology, obtaining a continuous quadrature signal tuning range from 1.66 to 5 GHz. As one of the main qualities of the frequency-injected oscillator scheme, an important phase-noise reduction is observed along the complete frequency range.
