Ultralow-Power Consumption High FoM Digitally Controlled Tunable Oscillator Utilizing SH-SAW Resonator Based on 4H-SiC Substrate

This article introduces a near-gigahertz, low-power-consumption, and low-phase-noise digitally controlled oscillator using a shear horizontal surface acoustic wave (SH-SAW) resonator on a LiTaO3/SiO2/ 4H-SiC multilayered substrate. The fabricated surface acoustic wave (SAW) resonator achieves a high Bode- ${Q}_{\max }$ of 3916. The high Q of the SAW resonator enables low phase noise and low power consumption for the oscillator. The Pierce oscillator is used to accommodate the asymmetric structures of the one-port SH-SAW resonator. In the nominal configuration, the fabricated oscillator achieves phase noise of −97.83, −125.90, and −151.98 dBc/Hz at 10 kHz, 100 kHz, and 1 MHz offsets from the output frequency of 984 MHz with a power consumption of $126.3~\mu $ W. The oscillator attains a figure of merit (FOM) of 221 dBc/Hz at 1 MHz offsets. The programmable load capacitance ( ${C}_{\text {L}}$ ) and bias resistor ( ${R}_{\text {B}}$ ) arrays are designed to adjust the output frequency and power consumption, enabling flexible power-performance trade-offs and frequency compensation for process voltage temperature (PVT) variations. The fabricated oscillator achieves an output frequency range from 977.9 to 986.6 MHz. The lowest power consumption of $66.4~\mu $ W can be realized by adjusting ${R}_{\text {B}}$ . The oscillator was measured at ambient temperatures from $40~^{\circ }$ C to $125~^{\circ }$ C. The output frequency increased from 983.1 to 985.9 MHz, with a frequency temperature coefficient of 17.2 ppm/°C. The oscillator tuning range covers frequency drifts over temperature. This work offers significant potential for ultralow-power consumption and low-cost Internet of Things (IoT) applications.