Very Linear and Low-Noise Ka/Ku-Band Voltage Controlled Oscillators

摘要

A simple and practical methodology to make microwave voltage-controlled oscillators (VCOs) very linear is presented. Incorporating a very short microstrip line ( λ_g/4) for varactor's bias feed, the C-V curve was shifted by a constant -ΔC and performed a capacitance tailored nearly proportional to V_(CONT)~(-2). This modification featured very linear VCO implementation at no expense of housing and phase noise performance. Ka- and Ku-band VCOs fabricated with this new technique exhibited a constant tuning sensitivity in a wide control voltage range (2-10 V). The phase noise level at 100 kHz offset was as low as -107 dBc/Hz for a 13 GHz-band VCO and better than -85dBc/Hz for a 38GHz-band VCO, due to combination of capacitor-coupled high-Q resonator and multiplier. This technology is very effective for quasi-millimeter-wave and millimeter-wave FM/FSK modulation and FMCW radar applications.