SUPERCAM SINGLE PIXEL BLOCK MEASUREMENTS

HAMDI MANI09/12/2008

LNA with an open input

Open LNA input SIS Device not mounted yet

Flange connector (2.92mm )(can’t find SMA which fits for theCenter pin of the 047 SR coax.)

047SR coax Grounded using H20E epoxy

Output cover Of the LNA

Top Cover Of the LNA

Detailed view of the IF part of the single pixel Mixer Block

“Home made” LNA output cover ! Sealed with epoxy . Temporary fix to make Sure we are fixing the problem and to make next version drawings of the LNA chassis .

Notch on the LNA cover left open .DC Lines are well bypassed and very well isolated from LNA RF output Board by a wall on the LNA cover

300K Data : output return Loss of the LNA (open input)

20 K Data : output return Loss of the LNA (open input)

The output spectrum (up to26GHz) doesn’t show any sign of oscillations@20K at Very high bias (up to 60mA ) with an open input (device not yet installed)

LNA with an SIS device at the input

H_22_+ SIS device mounted on the single pixel WAFER # T3-215-KWL2 Rn @300K was measured :

(Keithley2400 SourceMeter)

LNA #SC00 Chip#R6C1M9 (CIT-077 wafer)

Pinch off test at 300K : Vd=0.1VVg Id0 1.75mA-0.5 0.7-1 230uA-2 22-2.5 9uA

This test must be performedWhen in doubt about the LNA .300K Bias : Vd=1.8V Id=50mA Vg=1.6V20K Bias: Vd=1V Id=10mA Vg=1.6

H_22_+ SIS device

Indium foil under the LNA base to improve the grounding

Input and DC notches on the LNA cover are Left.Do not affect the feedback problem .The input notch allows bonding the SIS with the cover ON .

Some Notes about the package

•The Coax confines the fields better than the microstrip ,S12 is measured -50 withthe supercam LNA on a test fixture .

•The cover at the output of the LNA improves the isolation , this is a temporary fix And a new cover can be implemented in the base of the LNA .

•ALL the modifications done on the single pixel block can be removed (cable ,epoxy ,IF board …. ) and the block can be re-used .

300K Data : output Return Loss of the block (SIS at the input)

No oscillations seen at room temperature at high bias , SIS connected to the input of the LNA . No positive return Loss .

17K Data: output return Loss (SIS input ) , Horn mounted

The LNA was biased at high current up to 55mA with no oscillations up to 40GHz.No positive return Loss .The ripple on the curve is due to calibration (cal performed at 300K inside the cryostat)

Supercam Single Pixel block inside our “busy” “All purpose”20K cryostat

Supercam 1pixelBlock bolted to the 20K stage ,output Connected to SpectrumAnalyzer / VNA

Possible implementations of the “semi rigid coax” at the LNA output

LNA base is the only part that needs modification LNA tested by mounting it on a 50 ohm test fixture and bonding the input to a 50 ohmMicrostrip to coax transition .