A NOVEL HETEROJUNCTION BIPOLAR-TRANSISTOR VCO USING AN ACTIVE TUNABLEINDUCTANCE

This paper reports on the results of a novel HBT Voltage Controlled Os cillator (VCO) that incorporates a bias-tunable active inductor. This development benchmarks the first demonstration of a tunable active ind uctance controlled HBT VCO of this type. The active inductor topology can obtain inductances of up to 10 nH at frequencies up to 10 GHz and can be bias-tuned over a similar range. VCO's were designed at 4 and 1 0 GHz by implementing different active inductance values. A 29% freque ncy tuning range from 3.54 to 4.73 GHz was obtained for the 4-GHz desi gn. The output power varied from -1.2 to -0.2 dBm, respectively-less t han 1 dB variation over the tuning range. The phase noise is -70 dBc/H z at 100 kHz offset from the carrier. The new VCO topology can be impl emented without the use of backside vias or microstrip-matching compon ents and can be realized in a compact 1.0 x 0.7 mm2 area. The variable active inductance VCO topology provides a compact, high performance a lternative to the analog multi-vibrator oscillator circuit that genera lly has a smaller tuning capability and worse phase noise performance at microwave frequencies.