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

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.