Figure 1.

Sketch of the frequency shift due to an operation temperature of 300 °C with respect to the ISM-band for delay lines and resonators: (a) While only a part of the transfer function stays within the band at RT and 300 °C (red, blue), the devices can still be interrogated. The optimal operation point is set to 150 °C (green). (b) Using resonators, only one (red) stays in the band. The other devices marked as green, violet, and yellow get shifted out of the band when the temperature shift of ~280 °C is applied.