AMiBA PROJECT WEEKLY MEETING MINUTES

Date: 1 March 2001

Participants: K.Y. Lo, B. Martin, H. Wang, W. Warwick, M.Sinclair, M. Kesteven, M.T. Chen, H.C. Lu, Y. J. Hwang, R. Wei, W. Ho, Homing Jiang, P. Shaw, Jean Cheng

Issues and Description	Action by			Output
MMIC
1. Regarding the HPF purchasing issue, Leo has contacted the supplier, and is waiting for their quotation. 2 As for purchasing the InP HEMT & HBT MMIC foundry run from TRW, Huei has sent a schedule plan to TRW, and Paul also sent information to TRW for NDA preparation. The purchasing process as Stracy Bui of TRW told Huei, we need to sign a NDA first; TRW will quote after, and then finally sign a contract. Bui said that the export license would be not sent to us until that contract signed. 3 Regarding whether we could use those InP HEMT & HBT MMIC chips on the multipliers for prototype lag correlator and on the post amplifiers for prototype receiver, Huei has sent the contact person¡¦s information ¡V Stracy Bui of TRW to Mal . Mal and Warwick will prepare a letter to TRW, they will send a copy to Huei to read beforehand. 4 Huei got a copy of noise test data on the LNA modules from Neal Erickson/ UMass, the data shows that the noise of the best amplifier is around 28K minimum, and less than 38 K from 85-115 GHz, when tuned for higher gain. Neal said that these chips have some stability problem, but seem general usable. These chips are available for US radio astronomy, but a foreign application would be more complicated. Fred will talk to Sandy Wang first to see whether that NSF funded chips or not. Fred also mentioned that Bob Dickens who in charge of the Observatory in NSF will visit ASIAA in the beginning of April, and that would be a good opportunity to talk to him about if NSF is really the fund-holder. Huei will send Neal¡¦s e-mail to Fred, and Fred will forward it to Sandy and see what Sandy¡¦s suggest. Huei says that the best way to get those chips is to get the wafer of TRW to them , using their design and putting it on the mask. 5 Fred says that doing all the testing and putting together things in Hawaii will help a lot, because we don't need ship back and forth between US and here, and that¡¦s means we need to get a space to set up a lab in Hawaii. He asks Mingtang to list out what we need; how much space? What kind of instruments? And see what we can do. Mingtang had some idea, he will write out while he back here. 2 Eugene re-tested the Spacek's amplifier, and he got a better gain this time but still lower than the specs. He will try to low down the power lever further and test it again, Huei says. 3 Eugene says that he is still waiting for more information of the mixer & HPF from Russian firm. Since Mal already agreed to use their design on the HPF for AMiBA, so Eugene will find a way to get the Russian firm¡¦s quotation according to the drawing designed by Mal and his colleague. 4 Regarding the Sub-harmonic mixer packaging, Mal says that Mingtang here they plan to get drawing settle down with two engineers responsible for that and come out the design for InP mixer. Prototype. 5 Eugene, Mingtang, West and Hong-ming has visited Chungshang Institute last Friday, to discuss about the sub-harmonic mixer packaging as well as the w-band feed horn fabrication. Mingtang says that Chungtang will try to do the production, packaging and machining work for, but they don't like to take part in design in charge, and he thinks they don't have that capability. Fred says that it is important when the time we go for mass production and somebody is willing to do that work for us, since we don't have enough manpower.	H.C. Lu H. Wang W.Wilson H. Wang M.Sinclair H. Wang K.Y. Lo M.T. Chen Y.J. Hwang T.H. Chu Y.J.Hwng M.T.Chen M. Sinclair M.T. Chen Y.J. Hwang			Ongoing Ongoing Action item Action item Action item Action item Ongoing Ongoing Ongoing Ongoing
Lag Correlator Hybrid
1. Warwick says that Paul is testing the low frequency behavior of the multiplier at this moment, he has done some testing on the multipliers, and the packaging test is much similar to the simulation now. They have 3 dB bandwidth and with 16 GHz, and they response for the way quite remarkable out to 16 GHz, and so about 20 GHz with 10 to 15 dB down. So they are expected by the simulation as a 16 GHz device. They are dealing with some testing on the output noise, and that proceeding quite well. 2 Huei asks Warwick to help to test the chip from a semi-conductor manufacturer by middle March; Huei will provide a circuit board for that test. Warwick will keep on discussing this issue with Huei and student as will and see what they can do. 3 Regarding the final packaging for lag correlator, Warwick plans making the multipliers and putting them together on different board, the delay line and transistors, and putting it all in one chip, so it can save packaging cost. Warwick will work out how many wafers they require to use on the current design for example. It is the next thing along with figuring out the design of correlator on chip, and estimating the cost, the time scale as well. Since for the 20GHz bandwidth, we need to do another run making another design, test and production. Bob will go over all this issue in details with Warwick on off line. As for the prototype, Warwick says that the best they can offer is a 16 GHz device, and has to put it together on the print circuit board which using the same standard techniques as they are using now. Bob says that there are a lot to do here about development, he is worry about more iteration to get design to get the last band width, and he will bring up this topic to the science group, the implication and compromise this point sustaining 16 to 20GHz band width. and what they think really works about such development. Fred says that we could not afford the whole of extra money and whole of the extra time to get the extra bandwidth, and all this issue is needed to work out by off line in the other hand. 4 Regarding how to fit the prototype measurement with two correlators instead of four, Mike will bring this issue to the science meeting; Bob & Fred will follow up as well. 5 Regarding the 16-element correlator basis on mixer using power divider circuit, Jeff says that the current plan is to make the entire device in one piece alumina substrate in the firm Gramic, provide as an alternative correlator element to test the prototype stage, so available for cooperation as an alternative to the other possibilities in this summer, and it is no problem a make four correlator for for prototype. As an alternative, Jeff proposes to make the entire thing in silicon, and this will make the device smaller, and the cost is about $100K USD. Huei says that the silicon concept for integration, and its load is much higher than the GaAs especially when talking about 20GHz. Jeff will check this point to make sure it is ok. 6. Continuing to test the individual mixer using noise source. now they are going to measure the stability of the output, but they don¡¦t have sensitive enough equipment to see the fluctuation of the output. So they will add the LNA to the output, and see if they can measure on that. In mean while, he is still waiting for out put of the producer for lag correlator, he will keep on pushing them. Jeff will be gone in the next two weeks to south pole, so he hopes something comes out when he backs. The cost for of mixer chips for each correlator is about $600USD, Jeff says,	W.Warwick H. Wang W. Warwick W.Warwick B. Martin B. Martin M. Kesteven J. Peterson			Ongoing Ongoing Action item Action item Ongoing Ongoing
Receiver
1. Mingtang is still working on the material evaluation for receiver vacuum window, and has no new conclusion comes out yet. Jeff gives a new suggestion on the material, he will write down and send to everyone to think about. 2. Regarding the circular polarization issue, Mal will make a model according the information from Jeff. 3. Mingtang says that they almost finish the LO components layout arrangement, and now they are doing the thermos connection inside the dewar. Mingtang will discuss all design issue with Mal while he staying at AT.	J. Peterson M. Sinclair M.T.Chen		Action item Ongoing
IF/LO
1. Regarding the over-order fiber laser system, Eugene will inform the maker that we would like to delete a unit from our order, and ATNF will take over that one and buy from them according the original price without extra charge. Eugene will ask the maker to send a quotation to Warwick as well. In the mean time, Paul will proceed the change order procedure with Taida accordingly. 2. As to purchasing the optical fiber, Eugene has figured out he need 300 m. Bob will talk with Smithsonian people to see whether they could help us to get what we need from Sumitomo. In the Mean time, Fred will talk to Kaifu and see what he can do on this issue. 3. Regarding the optical amplifier, Eugene says it is very to find the required amplifier from any company, so he plans to add some gain on the LO amplifier in the individual module on the receive side and drop out the optical amplifier, and then see what effect on the LO phase noise and the performance of power level, he will discuss this issue with John as well. 4. As to the IF amplifier, Leo says that T.H. plans to use the chip form from HP, and he try to bind that chip by them. Warwick is concerning about the output power capability; he says that what we need for the IF amplifier is about ¡Ó 20dBM, and the HP one is only about 10dBM. Leo will discuss this issue with T.H. later.		Y.J.Hwang. P. Shaw Y.J.Hwang B. Martin K.Y. Lo Y.J. Hwang H.C. Lu T.H. Chu		Ongoing Action item Ongoing Action item
Platform/Mount/Dishes
1. Bob has given the specification mount & platform to Vertex and Chungshang as well. Paul will set up a meeting with Chungtang to go over all designs the details. And in the mean time, Bob will set up a telecon with Vertex to go over how far they have done and what the question are. Mike has forward the specs to Sydney Engineering Co, he will contact them and see what they are doing. 6 Jeff says that currently he and his student is working with a machine company to make a hexapod mount for the optical telescope. He will post on this information on web page.		B. Martin P. Shaw M. Kesteven		Ongoing
General issues
1. Fred asks Jeff to take a look at the work plan on web page, and feed back his comment to us. 2. Bob & Paul will go over the entire work plan with the responsible person separately after this meeting.
Next Meeting
7:30pm EDT, 8:30am Taiwan, 10:30 Australia, 4:30pm Tucson/Thursday/March 8, 2001