The behavior under multi-tone input waveforms is shown in Figure 15. When driven by 30 dBm input power per carrier to produce more than 100 W of total output power, split between two carrier frequencies, third-order intermodulation distortion is around 16 dB.

Figure 15

Figure 15 Two-tone intermodulation distortion at band center.

There have been impressive mmWave and THz TWT results reported by Stellant13,14 and Northrop,15 demonstrating a technological path to mmWave vacuum power devices. The volume has been low, but Elve has spent the past 18 months developing a high volume TWT fabrication process. Elve’s process is evolving with early prototype amplifiers providing feedback to improve subsequent units. Prototype gain performance is shown in Figure 16 with temperature performance shown in Figure 17.

Figure 16

Figure 16 Simulated and measured data for an early Elve prototype TWT.

Figure 17

Figure 17 TWT temperature performance.

CONCLUSION

TWTs have been a workhorse in communications, radar and imaging applications. They have an opportunity to return to the spotlight and showcase unprecedented performance at mmWave frequencies. Decades of demonstrated reliability, high power and efficiency are some of the advantages TWTs offer. Elve’s focus on large-quantity manufacturability ensures access to TWT advantages to enable the next generation of connectivity.

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