• Proposal 536: Quantum-Limited Very-Wideband 4-Kelvin RF and IF Amplifiers for ALMA

  • Reviewer 5

Grade: 4

Quantum-Limited Very-Wideband 4-Kelvin RF and IF Amplifiers for ALMA

1. Alignment with NA ALMA Partnership strategic goals;

This task is well aligned with the strategic goals as support for the development of these devices is called out specifically in the AO. Not only do these devices potentially replace SIS mixer front ends, but can also provided lower-noise and broader-bandwidth IF amplification.

2. Strength of the scientific case for the proposed ALMA upgrade concept; Comment on the relevance to the ALMA 2030 development documents.

Introducing wide-band front-ends into the AMLA receivers will enable multiple science cases. Increasing the IF bandwidth will reduce observation time and increase the chances of serendipitous discoveries.

3. Quality of the upgrade conceptual design; The design of the TKIP is well established and achieves state-of-the-art noise performance. Application of the TKIPs to ALMA’s IF amplifiers will be more complicated than to the front-end because an additional LO signal will need to be applied that currently isn’t in the ALMA receivers.

4. Readiness for production in the context of the ALMA Development Plan (the aim is to support a range of upgrades including both those which can be implemented rapidly and those requiring longer-term research and development);

The TKIP technology is still relatively young and the low-noise performance needs to be proven at 4K operation. This fits into the longer-term development efforts that would provide radical enhancement to the ALMA receivers. But if this effort is successful, plans could be made to start either replacing IF amplifiers or SIS mixer front-end with TKIP amplifiers.

5. Strength of the consortium organization (if applicable);

Excellent. JPL/Caltech are the pioneers of TKIP technology and have proven design and fabrication capabilities. Leading the proposal from NRAO/CDL provides perspective and experience with ALMA receiver development. Finally, the UVa collaboration to increase the Tc of the superconducting films provides low-cost fabrication research to mitigate the risk in moving to 4K.

6. Qualifications of the key personnel of the Study;

Excellent.

7. Technical expertise, past experience (also in series production, if relevant) and technical facilities in the Institutes taking part in the Study;

See #5.

8. Assessment of the level of risk inherent in the design;

Moderate. Moving from the tens or hundreds of milli-Kelvin to 4K is a dramatic increase in operation temperature of the TKIP devices, which will have an impact the sensitivity of the devices. The collaboration with UVa to increase the Tc of the superconductor is an appealing risk mitigation plan, considering their unique superconducting deposition facilities.

9. Strength of the Scientific Team supporting the Study;

N/A

10. Level of support guaranteed by the Institutes;

Good. By cost sharing the cryostat and labor with UVa, this project receives a significant bonus.

11. Budgeted cost of the Study;

The cost is relatively high, but seems warranted considering the strength of the collaboration across the four institutions and the potential benefits to ALMA if TKIP amplifiers were brought to maturity.

  • Reviewer 6

Grade: 0.5

Title: Quantum-Limited Very-Wideband 4-Kelvin RF and IF Amplifiers for ALMA

1. Alignment with NA ALMA Partnership strategic goals;

The proposed work is in line with both scientific goals and would strengthen NA ALMA's technical capabilities.

2. Strength of the scientific case for the proposed ALMA upgrade concept; Comment on the relevance to the ‘ALMA 2030’ development documents.

Reducing receiver noise is directly in line with ALMA 2030 priorities, and the promise of increased front-end bandwidth would contribute toward a broader-band overall system.

3. Quality of the upgrade conceptual design;

This work builds on a previous ALMA Development Project to design the amplifier device; work proposed here is testing and further development. The proposal overall is strong, but concentrates so much on amplifier development that it does not discuss the system consequences of shining a strong in-band pump signal on subsequent components, which may well saturate. If the study is to be useful for evaluating amplifier use in ALMA, it should be modified to include some analysis of this problem.

4. Readiness for production in the context of the ALMA Development Plan (the aim is to support a range of upgrades including both those which can be implemented rapidly and those requiring longer-term research and development);

This is a study that addresses a long-term goal.

5. Strength of the consortium organization (if applicable);

Excellent

6. Qualifications of the key personnel of the Study;

Excellent

7. Technical expertise, past experience (also in series production, if relevant) and technical facilities in the Institutes taking part in the Study;

Excellent

8. Assessment of the level of risk inherent in the design;

Low risk as a study, as the results on the amplifiers are likely to be valuable for further assessment. There is a risk that the pump signal would saturate subsequent components, preventing the technology from being useful to ALMA.

9. Strength of the Scientific Team supporting the Study;

Fine. The proposal applications concentrated on wide-band applications, where the amplifiers are only one of many components in a wide-band ALMA.

10. Level of support guaranteed by the Institutes;

The cryostat contribution is nice, but not really support specific to this proposal.

11. Budgeted cost of the Study;

Reasonable, but it is hard to assess the postdoc's contribution.

  • Reviewer 7

Title of ALMADev Proposal: "Quantum-Limited Very-Wideband 4-Kelvin RF and IF Amplifiers for ALMA" by Noroozian et al.

Review Comments

The proposers will continue to study amplifier technology based on Traveling-Wave Kinetic Inductance Parametric (TKIP) amplifiers. They propose to build both RF (in ALMA band 3) and IF frequency amplifiers. TKIP amplifiers have the potential of both increasing significantly the instantaneous bandwidth of ALMA receivers and lowering noise temperature, both of which can result in significant increase in array efficiency and speed.

The science case for the proposal is strong. There is no doubt that the increased bandwidth and sensitivity of TKIP amplifiers can significantly contribute to the long-term efficient use of ALMA.

However, there are some significant weaknesses in the proposal. While both the report and Figure 7 show simulated performance of the mm-wave TKIP amplifier, measured results are not shown. It has been several years since the mm-wave devices were fabricated. Measured results at different temperatures would go a long way to demonstrating the potential of these devices. While the performance of low frequency TKIPs show promise, it is easily possible that an hitherto unforeseen effect can significantly degrade their performance at higher frequencies.

Not enough justification is provided about noise performance of these devices whilst operating at a higher temperature of 4 K at millimeter wavelengths. If the physics of these devices is well-understood as claimed in proposal, at least simulations of base temperature could have been performed. It is not made clear how the foundries at JPL and UVML will contribute differently to the project. If they both are making similar devices, why have two foundries at increased cost?

For the RF devices, not much explanation is provided as to how a receiver will be built with such devices for ALMA. Will there be enough gain to use conventional semiconductor mixers? How will the LO signals be conveyed? What impact does it have on existing cryostat designs?

The proposing team is strong and brings together a diverse team with strong competencies in their respective areas.

The proposal length is in excess of the alloted 20 pages.

The study is well aligned with ALMA's long term goals.

Review Score: 7.0

  • Reviewer 8

No review received.

  • Reviewer 10

536 Quantum-Limited Very-Wideband 4-Kelvin RF and IF Amplifiers for ALMA 

Omid Noroozian

Score 5

The authors propose to develop broadband traveling wave kinetic inductance parametric amplifiers for use as both RF (~ w-band) and IF (4-12 GHz) amplifiers. It is currently believed that, despite potential loss in the mixer, that an SIS mixer first approach is superior to a semiconductor amplifier first approach for RF frequencies above 100 GHz. The hope is these amplifiers achieve sufficiently low noise performance in the several hundreds of GHz to enable an amplifier first approach in this frequency range. This is a follow-up program to an earlier ALMA funded study and the key goal is to test amplifiers in the 4 K temperature range.

I have a couple concerns with this proposal: (1) A major weakness of this proposal was the fact that it was stated that JPL had noise results for devices at 4 K, but these results were not shown in the proposal. (2) In addition, there seems to be sufficient funding elsewhere to support research in this topic area and it may be that it is still too much at the basic research level to justify supporting from ALMA funds. (3) The level of work at JPL seems insufficient to really get the devices working (just one amplifier fabrication cycle per year). This may to some extent be alleviated through UVA’s participation in the program, but if this is the case, why are devices being fabricated at JPL at all? (4) There has been no evidence that a device with sufficient interaction length can be realized that both suppresses the harmonic and has sufficient impedance match to remove the ripple effects that have plagued these devices since their inception. (5) The UVA driven purchase of a dilution refrigerator in support of this project was unclear. Such a fridge is great for mK measurements, but is overkill for 1-4K measurements, where a sorption fridge would do just fine. However, it appears that this is coming from other funds?

  • Reviewer 11
Grade: 2

Title Quantum-Limited Very-Wideband 4-Kelvin RF and IF Amplifiers for ALMA

1. Alignment with NA ALMA Partnership strategic goals; Well aligned with (long term) goals of improving sensitivity and bandwidth of ALMA (goal 1.1).

2. Strength of the scientific case for the proposed ALMA upgrade concept; The proposal describes how the TKIP amplifier technology would dramatically reduce the observing time required for several key science areas, especially those requiring continuum measurements or multiple tunings to study several spectral lines. The case is quite convincing, but the full benefits would of course require several other upgrades to take advantage of the ~40 GHz of instantaneous bandwidth that could become available. Comment on the relevance to the ‘ALMA 2030’ development documents. The superconducting amplifiers proposed here are explicitly called out in the ALMA 2030 development plan as an example of an important new technology

3. Quality of the upgrade conceptual design; The concept design and plan of work are well thought out and based on strong prior work demonstrating that the deliverables of this proposal can be achieved. My only concern is that this proposal runs in parallel with building out of a new lab infrastructure, which can lead to significant schedule slippage. However, this risk will likely pay off in the long term by developing the technology locally at the CDL and UVa

4. Readiness for production in the context of the ALMA Development Plan (the aim is to support a range of upgrades including both those which can be implemented rapidly and those requiring longer-term research and development); This is a long-term proposal, so it seems that the estimate given in the proposal of 3-5 years before engaging a full deployment project. The proposal makes a good case that the prototype devices proposed would be completed in the timeframe of the current project.

5. Strength of the consortium organization (if applicable); While the JPL, CDL, and UVa teams have well defined work packages, a geographically distributed team like this does introduce some inefficiency. I would have liked to have seen more discussion of how to keep the teams in sync, but I assume that it won’t be an outsized issue.

6. Qualifications of the key personnel of the Study; The team includes many of the people involved in the original development of this technology, so it’s hard to imagine a stronger team to take on this task. Having the known successful fabrication of these devices from JPL available is particularly important.

7. Technical expertise, past experience (also in series production, if relevant) and technical facilities in the Institutes taking part in the Study; See response to item 6

8. Assessment of the level of risk inherent in the design; This is by nature a high-risk/high-reward project. While these amplifiers have measured performance in line with predictions, the engineering challenges involved are sometimes constrained by material properties and lithographic capabilities. Thus there is some chance the promise of the technology may not be possible to realize in the context of ALMA. However, the benefits would be truly transformative, and hence the risk is worth taking.

9. Strength of the Scientific Team supporting the Study;

10. Level of support guaranteed by the Institutes; Seems good/excellent

11. Budgeted cost of the Study; The budget seems reasonable given the scope, prior work, and in kind contributions.

-- AlWootten - 2017-07-18
Topic revision: r2 - 2017-07-18, AlWootten
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