A 1.2 V, 0.9 mW UHF VCO Based on Hairpin Resonator in Paper Substrate and Cu Adhesive Tape

A 1.2 V, 0.9 mW, 998 MHz voltage controlled oscillator (VCO) adopting a distributed hairpin resonator in paper substrate is described. The microstrip resonator exploits a copper adhesive tape that is shaped by a photo-lithographic process and transferred to the hosting substrate using a sacrificial layer. To minimize the number of components, a cross-coupled differential VCO circuit is adopted. As a consequence only 3 external devices are necessary: a single-package BJT pair, a resistor and a by-pass capacitor. The measurements show a phase noise of -99 dBc/Hz at 100 KHz offset from the carrier. At 1.2 V the output power is -22 dBm, whereas the tuning sensitivity is about - 100 MHz/V. The proposed design shows the feasibility of low-power oscillators for autonomous wireless sensors based on green materials.