A NOVEL BROAD-BAND MMIC VCO USING AN ACTIVE INDUCTOR

This paper proposes a novel brood-band MMIC VCO using an active induct or. This VCO is composed of a serial resonant circuit. in which the ca pacitor is in series with an active inductor that has a constant negat ive resistance. Since the inductance value of this active inductor is inversely proportional to the square of the transconductance and can v ary widely with the FETs' gate bins control, a broad-band oscillation tuning range can be obtained. Furthermore. since this active inductor can generate a constant negative resistance of more than 50 Omega, the proposed VCO can oscillate against a 50-Omega output load immediately without using additional impedance transformers. We have fabricated t he VCO using a GaAs MESFET process. A frequency tuning range of more t han 50%, from 1.56 to 2.85 GHz, with an output power of 4.4+/-1.0 dBm. was obtained. With a carrier of 2.07 GHz, the phase noise at 1-MHz of fset was less than -110 dBc/Hz. The chip size was less than 0.61 mm(2) , and the pna er consumption was 80 mW. This broad-band analog design can he used at microwave frequencies in PLL applications as a compact alternative to other types of oscillator circuits.