ALMA MEMO #498

The ALMA Band 6 (211-275 GHz) Sideband-Separating SIS Mixer-Preamplifier

A. R. Kerr (1), S.-K. Pan (1), E. F. Lauria (1), A. W. Lichtenberger (2),
J. Zhang (2), M. W. Pospieszalski (1), N. Horner (1), G. A. Ediss (1),
J. E. Effland, (1), R. L. Groves (1)

The ALMA Band 6 (211-275 GHz) receivers use sideband-separating SIS mixer-preamplifiers with dual 4-12 GHz IF outputs. The sideband-separating mixers are of the phasing type, with the LO driving two component mixers in-phase and the RF signal connected to the mixers through a quadrature hybrid. The IF outputs of the mixers are amplified, then combined in a quadrature hybrid which separates the upper and lower sideband signals. The RF circuit components are all in a single split waveguide block -- quadrature hybrid, LO power divider, LO couplers, cold image termination, and the two mixer chips. To achieve the wide IF bandwidth, a low-parasitic mixer is used and the preamps are bolted directly to the mixer block.

View a pdf version of ALMA Memo #498.