Fig. 1. Illustration of InP-based RTD structure

Fig. 2. Peak voltage（V_p）and peak current（I_p）vs（a）doping density，（b）t_B，（c）t_W，（d）t_S

Fig. 3. （a）Photo of the fabricated RTD，（b）measured I-V characteristic of the RTD device

Fig. 4. Small-signal equivalent circuit of RTD

Fig. 5. （a）schematic of the proposed bow-tie antenna，（b）antenna with Si-lens mounting

Fig. 6. （a）VSWR and（b）gain of the proposed antenna with Si-lens

Fig. 7. Schematic of oscillator package

Fig. 8. The photograph of the packaged oscillator

Fig. 9. （a）Block diagram of measurement scheme，（b）photo of the test environment