1. K-Band Focal Plane Array: Integrated Downconverter Module #1 Matt Morgan and Tod Boyd National Radio Astronomy Observatory 8/7/2008

2. IDM1 is Complete

3. IDM2 is Not Complete – One Key Part Missing I mistakenly ordered the wrong size feedthru header for this module. They have been re-ordered, and are expected to arrive in mid-September.

4. IDM1: Measured Gain The bandpass is a little narrow. I will show later that it is not the filter. I probably just need to raise the lid slightly.

5. IDM1: Measured Gain IF Response shows a lot of ripple. I believe this is related to cavity effects on the PCB-side – which will not be present on IDM2.

6. IDM1: Measured Image Rejection Image rejection at ±1.2-3 GHz offsets is better than 35 dB.

7. IDM1: Measured Image Rejection Image rejection at ±5.9-7.7 GHz offsets is better than 32 dB.

8. IDM1: Measured Gain Compression Output 1 dB compression point is about +7 dBm.

9. IDM1: Measured LO Power Requirements

10. IDM1: Measured Channel Isolation There seems to be excessive crosstalk between channels (-20 dB), having a strong IF dependance, but virtually no RF/LO dependance – this strongly suggests that the crossover is occuring in the IF circuit inside the PCB cavity.

11. IDM1: Measured Return Loss Poor return loss needs investigation.

12. IDM1: Measured Return Loss Poor return loss needs investigation.

13. IDM1: Measured Return Loss Poor return loss needs investigation.

14. Probe Measurements on Filters Dynamic range of the measurement was limited at the high frequency end, but the passband looks perfect.

15. Probe Measurements on Filters Perfect.

16. Compliance Matrix for Single Pixel Prototype parametersymbolspec/predictedmeasurementcomments noise temperatureTeTe 600 – 800 Knot measured gainG30 dB gain rippleG max – G min 3 dB8 dBpresumed PCB cavity effect output powerP out -25.5  0.5 dBm assuming predicted front-end gain headroomHR+40 dB+33 dBprobably ok LO1 power required P LO1 -3  5 dBm+1  8 dBm LO2 power required P LO2 +3  5 dBm image rejectionIR25 dB32 dB channel isolationIso30 dB20 dBpresumed PCB cavity effect return lossRF input IF output LO1 input LO2 input -17 dB -19 dB -12 dB -10 dB -11 dB -6 dB -12 dB need to verify transition designs massM250 g316 gIDM2 will be much less, average should still meet spec

17. Future IDM1 Revisions 1.Modify ALH444 bias circuit for better gain repeatability. 2.Modify PCB cavity to include a metal barrier between IF circuits in both channels – this should improve channel isolation and IF gain flatness 3.Investigate cause of return loss problems – may require re-design of the transitions 4.Raise the lid above the filters to prevent de-tuning. 5.Clean up other minor PCB issues