Arcetri Technical Reports 2/2003

2nd Generation MMIC sampler for ALMA - Design report

G. Collodi, G. Comoretto

INAF - Arcetri Astrophysical Observatory

Abstract

A sampler circuit for the Atacama Large Millimeter Array, based on a GaAs 0.12 um process, has been designed and tested by simulation. The use of a separate sampler before the BiCMOS digitizer allows a larger time for quantization decision, and reduces the timing requirements on the digitizer. The predicted performances fulfills the requirements for the ALMA sampler/digitizer. In particular the aperture time is < 50 ps, and the bandwidth in excess of 4 GHz. A first version of the chip has been fabricated, but a layout error prevents it to operate correctly. Recovery actions are being attempted, but it is difficult that a working unit will be available in due time. 

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