Fig. 4
Performance test of the MEMS resonator under only off-chip oven control. a Temperatures of the aluminum case (blue solid line, measured by the outer temperature sensor) and the metal package (red solid line, measured by the inner temperature sensor) under the first stage oven control. The inset shows that the temperature of the metal package was maintained within 35 ± 0.001 °C after a warm-up time of 3750 s. b The frequency of the MEMS resonator was measured for a duration of 1800 s after the temperature of the resonator was maintained within 35 ± 0.001 °C. A residual frequency drift of 2104 ppb was observed. c Temperature oscillation during the warm-up of the first stage oven control. d The rapid compensation capacity of the A-f control module
