Issues and Description

Action by

Output

MMIC- W- Band InP HEMT LNA

1.  Regarding the Sub Hamonic Mixer’s chip test at ATNF, they got some results about "conversion loss" and "return loss". Huei would like to know if it is possible to retest the chip to measure the "isolation property". Mal says he try to work out some information by the next week.

2.Regarding the JPL's stuff, Todd Gaier sent a formal request to the JPL's headquarter to request to loan us  two modules of InP LNA MMIC. Huei didn’t hear anything from Todd yet; he will contact Todd to find out the status by next week.                                                       

3.As for the 0.1um GaAs HEMT design work is still ongoing, all the chips will be sent to CIC for reviewing by next week., and to finish the design by Mid of Oct, so far everything is on schedule.                                                                         

4.Huei says there is no further progress report from TRW for the export license of InP HEMT, so he will contact Joyce to find out the status. 

5.Waveguide filter - Huei already gave the design goal to Prof. Wu, he will check with Prof. Wu to see if he can follow the design goals to build a module for us. Huei said since that is a back up approach, he is not pushing him to do so. Mal said that at this moment they are investigating a couple of things, once he got that data, he will talk about it more.  

6. As for purchasing the 4 units of 82~106 GHz amplifiers from NRAO, we sent a letter to NRAO for export license application. Once the internal purchasing procedure was completed we will release that order to NRAO.

7. Mal says they got the first chip back from TRW for w-band InP LNA, but they found 15 of 21 chips are damaged. So they will send them back to TRW. At this moment, they preparing to test these 6 w-band amplifiers.

8. As to the MMIC design for InP LNA, Huei says the design work is still ongoing.

9. Prof. Chu says he didn't receive Specek's components yet, but they should be arrived soon according to Specek's email.

M. Sinclair

H. Wang

H. Wang

H. Wang

H. Wang

M. Sinclair

P. Shaw

M. Sinclair

H. Wang

T.H. Chu

Next week

Next week

Ongoing

Ongoing

Ongoing

Ongoing

Ongoing

Ongoing

Ongoing

soon

Lag Correlator Hybrid

1.For the 17 lag correlator, Jeff said the Gramic is till working on that, he don't expect anything for several more weeks.

2.For the Gilbert Cell Multiplier spec, H. Wang reminds J. Peterson to generate a specification to help S.S. Shen and his student to design that amplifier. He also asks W. Wilson to give his comment on that spec. He hopes to read and to discuss their inputs in the next week.

3.Huei says that according the Fushimi's paper; the diode mixer has a worse loss than the conventional mixer at RF &LO powers input. He will email that paper to Jeff to review. Jeff agreed to compare it with what he has made in his lab. Jeff will also email everyone the responsive result in lab.

4.Jeff said that the email he did send around , what he realize that the signal level arriving both Gilbert Cell and mixers are quiet small, in few microwatts (-25dBm). The division of tree structure to be made with the resistor, which make that structure much smaller. Warwick says the resistor is much lower in the tree structure, and it certainly is the advantage to achieve that bandwidth as we talk about. The structure will be bigger than the structure of Gilbert Cell itself, probably twice as big. Jeff will keep on thinking about an idea of merit.  He may try it, perhaps to build one.

5. Jeff said the progress of the Gramic today about switching that they are thinking for us for the tree structure and the resistance divider.  This makes the two technology re-testing as different as possible, and we learn more as we do that way, so his suggestion is that we do that by the tree structure with mixer from that MMICs, and then we go continuously with the delay line lag correlator. Warwick

  says he have not decided definitely on that structure. But he will come out some simulation with other work they do. Jeff said he would like better for what he try, so he probably will go ahead that direction. Warwick agrees with Jeff to choose that mixer tree structure.

6. Warwick said he is still waiting for the HBT Gilbert Cell multipliers coming back, and expecting the wafer to arrive in by now , but he can't get informaton on TRW for when they can get the MMIC coming. TRW should test it on 19th, and then see how they are going.  Warwick is still working on the 1~4 GHz lag correlator by using the commercial multipliers , he is constructing and testing it, and this

  goes very well. So he hopes something comes out in a couple of weeks.

7. Warwick said he had communication with Prof. Chiueh concerning about the output processing prototype as well as the CMOS chip design. Fred said it would be good to keep Prof. Chiueh talking to Warwick.

8. Ray Wei says last week he received a letter from CIC advising the process model has been updated, so now he is doing the simulation accordingly. Prof. Chiueh suggests him to simplify the circuit further more, so he is working on this as well. Besides, there is a trade off between linearity and frequency range. He propose to limit the output frequency by 10 MHz with 2 MHz changing range. He will keep  us informed the progress of his work.

9. As for the Gilbert Cells Multiplier, Paul Roberts and Warwick think the GaAs HEMT is worse than the HBT due to high noise and conversion loss. Huei said they has completed 80% of the design work with the GaAs HEMT for Gilbert Cells Multiplier, he will continue to finish that work. To solve the high loss problem, Huei suggests put amplifiers in front of RX and LO circuits.  Without testing , Warwick is wondering how practicable that solution would be. Huei says he already sent some simulation results to Warwick , Paul Roberts and Jeff to look. Warwick and Jeff is not here today, so he hopes to discuss it with Warwick and Jeff by next week.

J. Peterson

J. Peterson

J. Peterson

J. Peterson

J.Peterson

W. Wilson

Ray Wei

H. Wang

W.Warwick

Ongoing

ASAP

ASAP

ASAP

ASAP

Ongoing

mid Nov

next week

Receiver

1. Yugene says he found the Atlantic Microwave Company - , their OMT can meet with our requirement on bandwidth of 85 ~105 GHz. So he talked it with Mingtang, and they are planning to buy two for the prototype, that price is around 6K for each. 

2. Jeff says he has some photographs about NRAO's amplifiers, and he will send them to Bob and Mingtang to take a look. 

3. Bob said he also got some more information about NRAO's OMT in the last few days, the price is between 6K to 8K. He is also starting some discussions with Graham Morey at NRAO, Graham is interested in the possibility to collaborate with one of you, they need about early part next year, and we need a couple of, so we could go together for a lot of these. They don't currently have the equipment they

  need to do this, we probably have all the equipment here. But they don't want be involve in production, they want involve the prototype. 

M.T. Cheng

J. Peterson

Ongoing

Ongoing

LO/IF

1. Eugene says in the past week he modified the photonic LO block diagram according to the latest AMA memo written, he is talking about the noise problem about the LO skin. According to his suggestion, he drop out the EDFA from photonic Lo system, it's means we need to increase the power level of the DFE fiber laser of the system. The power level required for the whole array is about 20 to 27 dBA. He also made some modifications on some part of the system, he will send that block diagram in pdf file to everybody after this meeting.

2. As to the purchasing for the instruments are still ongoing, but due to the changing of the specs, he will review the potential suppliers of the mixer laser. The other part, such as the high emulation LED for the calibration source and EDFA, he already got the quotation, so the paper work for purchasing is on going. He also sent out an inquiry for the photo mixer chip for packaging to the w-band fabrication, he is waiting for that quote. 

3. As to the IF, Prof. Chu says he is making the equalizer for the cable which base on George's design, he is also starting to design the equalizer for the amplifier, that amplifier is base on the HP 20GHz wide band.      

4. Eugene's travelling schedule to NRAO has been settled down, he will departure on Sept. 23 and back on Oct. 6.

Y.Hwang

Y.J.Hwang

T.H.Chu

Ongoing

Ongoing

Ongoing

30 cm antenna

1.    Michael says G. James is still working on the mutual coupling problem between small antenna.

2.    Michael says that G.James recommend using a dish instead a horn.

Bob says it would be easier if it comes a conclusion that one can use the dishes of 30cm, that would make the whole problem easier about the changing between the 30cm dishes and 1.2m dishes. He asks Michael that how soon could we get the finite answer on that feasible way to go? Michael says the calculation in details probably would be come out by the next week.  

M.Kesteven

next week

Platform/mount

1.  Michael says regarding the Ravi's comments on platform, he just want to emphasize what Ravi 's saying is that he think the platform is not the only way to go. Michael says that in relating with the shadowing Ravi did a lot of work, trying to understand the details of shadowing with that ride. His conclusion for that was the moment the antennas are on the same place, so one antenna can see a little bit of the other, then you are in trouble. He feels whether the separate mounts probably bring you more difficulties than you gain.

2.  Bob says he is still working on the design for the prototype, he should have something more concrete by the end of this week for comment on, he will circulate it around.

B. Martin

Next week

Site acquisition

Bob says he talked with John barnes of the Mauna Lao Observatory last week. John is the Station Chief of the MAO opeation in Hilo. It sounds very promising that our needs may mesh with what they look for in the use of the site. Bob says he is planning to visit Hilo in November, to take a look at the application process that we need to do. He hopes we could test the prototype over there by next year.  

B. Martin

Ongoing

Specification and Project Book

1.  Bob says this is the worst case the area we have specification difficulties at this moment, he don't see a resolution on this for another year until we actually have a prototype to test. Unless you or somebody else conversion some conclusion on this issue. Michael says in this stage, they are really concentrating on CMB, and not much clear on SZ. But Ravi told him that direction another day, and they start looking more seriously at that case through.

2.  Bob suggest forming another group to discuss these observational technique relative issues and resolve them between Ravi, Michael, Fred, himself and others. Bob requests Michael to ask Ravi what is a good date to have a phone meeting for him. Michael agrees to do that.

3.  Michael says he just sent out a copy of "computing issues" to Bob and Fred at last night. Bob says he just saw it this morning and he didn't read it yet.

4.  As to the specification drafted by Michael, Bob hopes to put it out anybody else in the court next week.         

M.Kesteven

M.Kesteven

B. Martin

B. Martin

B. Martin

Ongoing

ASAP

Ongoing

nextweek

Next Meeting

8:30pm EDT, 8:30am Taiwan, 10:30 Australia, 5:30pm Tucson/Thursday/21 September 2000