A 135–150-GHz Frequency Tripler With Waveguide Filter Matching

Abstract

The design and performance of a WR-5 band 135-150-GHz Schottky diode-based frequency tripler which uses waveguide resonator filters for low loss impedance matching is presented in this paper. The filters used in this paper provide filtering, impedance matching, and microstrip (MS) to waveguide transitions in one structure. The matching optimization is achieved by scaling the external quality factors and adjusting the resonance frequency of the filter cavities. This approach transfers most of the tripler's matching networks from MS circuitry to lower loss rectangular waveguide resonators. This is desirable and useful in particular for submillimeter wave and terahertz frequencies. The device presented is a 47.5 to 142.5 GHz biasless frequency tripler with a 15-GHz output bandwidth. The tripler was measured to have a conversion loss of 13.1-14 dB across the band, at an input power of 17 dBm. The measured S 11 at the input port is better than 15 dB and all the reflection zeros from the filter resonances are distinct. The good agreement between measurements and simulations verifies the accuracy of the filter-based design approach.

A 135–150-GHz Frequency Tripler Using SU-8 Micromachined WR-5 Waveguides

“…In this work, the impedance matching of the diode chip is realized by waveguide filters using a coupled resonator design methodology [26], [27]. The circuit configuration is shown diagrammatically in Fig.…”

“…The two resonators belong to the input and output filters, respectively. Coupled resonator filters were successfully used as impedance matching networks for a wide range of devices such as mixers [26], frequency multipliers [27], and amplifiers [28]- [33], from a few gigahertzes to 300 GHz. One advantage is the compact circuit size with filtering, matching, and the waveguide to microstrip (MS) transition to be realized in one structure.…”

“…One advantage is the compact circuit size with filtering, matching, and the waveguide to microstrip (MS) transition to be realized in one structure. The other benefit is that lower loss can be achieved, as most of the matching elements were moved from the MS circuit into the waveguide resonators [26], [27]. The detailed design procedure of the triplers is given in Section II-A.…”

“…To design the input and output matching filters, the procedure discussed in [27] has been used: The tripler was designed to have an input power of 50 mW and output frequency…”

“…It should be noted that the impedances are frequency (and power) dependent and only the value at the center frequency is listed here. The non-50-impedances obtained can be directly matched within the filters, as discussed in [27]. The 3-D modeling, full-wave simulation and optimization of the impedance matching filters were done in CST, and the obtained physical dimensions are shown in Fig.…”