Wideband passive circuits for sideband separating receivers

Paper i proceeding, 2018

In this work, we present the design and characterization a new generation of compact wideband quadrature hybrids operating both at room and cryogenic temperatures for prospective use in the IF chain of 2SB THz receivers. The compact wideband design employs a multi-section topology (coupled line coupler - Lange coupler- coupled line coupler) and thin-film technology with gold plated transmission lines and air bridges to connect the fingers of the Lange coupler (middle section). The hybrids were designed to have the amplitude and phase imbalance better than 0.6 dB and ±3° respectively over a 3.5-12.5 GHz and 4-16 GHz frequency bands. The experimental verification of the assembly at 293 K and 4 K shows very good agreement between the measurements and simulations with amplitude imbalance better 0.5 dB and maximum phase imbalance of ±1.5°.