A 16.8dB Input Power Range Microwave Rectifier with a Small Capacitor in Parallel with the Diode
To extend the input power range, a microwave rectifier based on the elimination of input matching circuit is presented. In the proposed topology, a small capacitor is in parallel with diode and a λg/10 short-ended transmission line is placed between the cathode of diode and ground. The small capacitor modifies the real part of the impedance of rectifier and the λg/10 cancels the imaginary part of diode capacitive impedance. Meanwhile, the λg/10 short-ended transmission line presents an almost open circuit at 2nd and 3rd harmonic. By carefully choosing the value of capacitor and the width of λg/10, there is no need for input matching or input low-pass filter. The fabricated rectifier has maximum RF-DC conversion efficiency of 87.7% at 24.8 dBm input power. The measured efficiency remains above 70% with the input power form 8.2 dBm to 25 dBm and the operating frequency form 1.5 GHz to 2.2 GHz.