ALMA Memo #360
Design of Sideband Separation SIS Mixer for 3 mm Band

Vessen Vassilev and Victor Belitsky

As a part of Onsala development of a single sideband mixer for ALMA band 7 (275-370 GHz), we present design of a prototype sideband separation mixer for 85-115 GHz.  The mixer employs a quadrature scheme with two identical DSB SIS mixers pumped by a local oscillator with 90° phase difference.  The mixer uses a new device, a double-probe coupler, which splits the input RF signal and provides transition from a waveguide to a microstrip line, allowing the integration of all mixer components on the same compact substrate and thus ensure a high degree of similarity in the SIS junction performance and the geometry of all the mixer elements including integrated tuning circuitry.

We present the design of all the mixer components, detailed simulation results using High Frequency Structure Simulator and measurements of the double probe coupler.

View a pdf version of ALMA Memo 360.