Cycle 8 NRAO ALMA Development Study Proposal – Extending IF Bandwidth of Band #6 SIS Mixer-Preamps to 12 GHz and 16 GHz with Optimal Noise Performance: An Experimental Demonstration

PI: Marian Pospieszalski, NRAO

ABSTRACT

This proposal has two main developmental goals: 1) Development of new designs of broadband IF amplifiers using commercially available devices from Diramics, Inc. that are integrable with the existing and future designs of Band# 6 SIS mixers. That should include 4-16 GHz and 4-20 GHz versions. The state-of-the-art cryogenic low noise performance of Diramic’s devices has already been demonstrated in existing 5-10 GHz IF amplifiers as well as in in 35-52 GHz Band #1 amplifiers. The noise performance of Diramics devices equals on the average the best ever demonstrated in any technology. 2) Demonstration of direct integration with optimal noise performance of these IF amplifiers with the existing Band #6 SIS mixers. This should allow for extending instantaneous bandwidth of an individual mixer to 24 GHz or 32 GHz per polarization. Extending the instantaneous IF bandwidth of the existing Band #6 receiver from 5-10 GHz to 4-12 GHz has already been experimentally demonstrated. Extending the highest frequency within the IF bandwidth always has to result in some penalty in IF bandwidth averaged noise temperature of an SIS receiver. An experimental comparison of Band #6 mixer optimally integrated with IF amplifiers having 8, 12 and 16 GHz instantaneous bandwidth should settle the question whether extending the IF bandwidth at the cost of receiver noise is scientifically justifiable. It therefore should help guide any future SIS mixer development for ALMA.