Design and fabrication of a millimeter-wave MMIC HBT VCO with consideration for modulation linearity and low phase noise

A 38 GHz-band MMIC (Monolithic Microwave Integrated Circuit) VCO (Voltage Controlled Oscillator) has been developed for the millimeter wave radio communications systems, using the AlGaAs/InGaAs HBT (Hetero Bipolar Transistor). There are the p+/p re-grown base contact and several other technologies in fabrication process of HBT used for realizing low 1/f noise of the oscillation transistor. Furthermore, unique circuit technology to maximize the quality-factor of a resonator and a base-collector junction diode p-n varactor are designed for the low phase noise characteristics and the linear frequency modulation characteristics. The MMIC HBT VCO exhibit a phase noise of 85 dBc/Hz at 100 KHz off the carrier and a frequency modulation linearity of less than 3.6%p-p with the maximum frequency deviation of 37.5 MHz at 38 GHz band.