{"action":"created","issue":{"url":"https://api.github.com/repos/sinara-hw/BaseMod/issues/2","repository_url":"https://api.github.com/repos/sinara-hw/BaseMod","labels_url":"https://api.github.com/repos/sinara-hw/BaseMod/issues/2/labels{/name}","comments_url":"https://api.github.com/repos/sinara-hw/BaseMod/issues/2/comments","events_url":"https://api.github.com/repos/sinara-hw/BaseMod/issues/2/events","html_url":"https://github.com/sinara-hw/BaseMod/issues/2","id":351808091,"node_id":"MDU6SXNzdWUzNTE4MDgwOTE=","number":2,"title":"BaseMod remove power detector in next revision? ","user":{"login":"gkasprow","id":4325054,"node_id":"MDQ6VXNlcjQzMjUwNTQ=","avatar_url":"https://avatars3.githubusercontent.com/u/4325054?v=4","gravatar_id":"","url":"https://api.github.com/users/gkasprow","html_url":"https://github.com/gkasprow","followers_url":"https://api.github.com/users/gkasprow/followers","following_url":"https://api.github.com/users/gkasprow/following{/other_user}","gists_url":"https://api.github.com/users/gkasprow/gists{/gist_id}","starred_url":"https://api.github.com/users/gkasprow/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/gkasprow/subscriptions","organizations_url":"https://api.github.com/users/gkasprow/orgs","repos_url":"https://api.github.com/users/gkasprow/repos","events_url":"https://api.github.com/users/gkasprow/events{/privacy}","received_events_url":"https://api.github.com/users/gkasprow/received_events","type":"User","site_admin":false},"labels":[{"id":1027986259,"node_id":"MDU6TGFiZWwxMDI3OTg2MjU5","url":"https://api.github.com/repos/sinara-hw/BaseMod/labels/area:analog-mezzanine","name":"area:analog-mezzanine","color":"ededed","default":false},{"id":1027986263,"node_id":"MDU6TGFiZWwxMDI3OTg2MjYz","url":"https://api.github.com/repos/sinara-hw/BaseMod/labels/area:schematics","name":"area:schematics","color":"ededed","default":false},{"id":1027986266,"node_id":"MDU6TGFiZWwxMDI3OTg2MjY2","url":"https://api.github.com/repos/sinara-hw/BaseMod/labels/type:discussion","name":"type:discussion","color":"ededed","default":false}],"state":"open","locked":false,"assignee":{"login":"jbqubit","id":20543958,"node_id":"MDQ6VXNlcjIwNTQzOTU4","avatar_url":"https://avatars1.githubusercontent.com/u/20543958?v=4","gravatar_id":"","url":"https://api.github.com/users/jbqubit","html_url":"https://github.com/jbqubit","followers_url":"https://api.github.com/users/jbqubit/followers","following_url":"https://api.github.com/users/jbqubit/following{/other_user}","gists_url":"https://api.github.com/users/jbqubit/gists{/gist_id}","starred_url":"https://api.github.com/users/jbqubit/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/jbqubit/subscriptions","organizations_url":"https://api.github.com/users/jbqubit/orgs","repos_url":"https://api.github.com/users/jbqubit/repos","events_url":"https://api.github.com/users/jbqubit/events{/privacy}","received_events_url":"https://api.github.com/users/jbqubit/received_events","type":"User","site_admin":false},"assignees":[{"login":"jbqubit","id":20543958,"node_id":"MDQ6VXNlcjIwNTQzOTU4","avatar_url":"https://avatars1.githubusercontent.com/u/20543958?v=4","gravatar_id":"","url":"https://api.github.com/users/jbqubit","html_url":"https://github.com/jbqubit","followers_url":"https://api.github.com/users/jbqubit/followers","following_url":"https://api.github.com/users/jbqubit/following{/other_user}","gists_url":"https://api.github.com/users/jbqubit/gists{/gist_id}","starred_url":"https://api.github.com/users/jbqubit/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/jbqubit/subscriptions","organizations_url":"https://api.github.com/users/jbqubit/orgs","repos_url":"https://api.github.com/users/jbqubit/repos","events_url":"https://api.github.com/users/jbqubit/events{/privacy}","received_events_url":"https://api.github.com/users/jbqubit/received_events","type":"User","site_admin":false}],"milestone":null,"comments":16,"created_at":"2018-08-18T09:58:41Z","updated_at":"2018-12-15T22:06:13Z","closed_at":null,"author_association":"MEMBER","body":"_From @jbqubit on December 4, 2017 21:26_\n\n- [ ] Consider removing power detector from Allaki\r\n\r\nContext:\r\n- Usefulness of power detector is unclear:\r\n  - It only connects to 24-bit ADC, which is very slow and software/gateware support not funded yet.\r\n  - Gain flatness of Sayma/BaseMod should be fairly good compared with the amplifiers, filters etc that are used after it. Thus one generally wants to do power-levelling at the point of load, not at Sayma RF connector\r\n  - BaseMod will have a low-noise MSPS ADC with programmable-gain front-end. Users can place a small power detector near their load. e.g. ADL5511. This will allow closed-loop feedback to the RF at the point where the user cares. Moreover, thermal environment of external power detector can be better controlled, allowing improved stability. External power detector can potentially also be used for using feedback to remove thermal transients in amplifiers etc.\r\n- Power detector is the biggest component on BaseMod. BaseMod is very cramped, removing this will help quite a bit. It also reduces the amount of software support needed for BaseMod (and the number of things that need production testing).\r\n\r\nRisk:\r\n- Low, just remove a component!\r\n\r\n---\r\n\r\nMoving from https://github.com/m-labs/sinara/issues/269. \r\n\r\n@hartytp asks\r\n> Does anyone object to removing the power detector from BaseMod v1.1? cf #397\r\n\r\n@dhslichter responds\r\n> The point of the power detector is to noise-eat at the output of the DACs. What is it costing us?\r\n\r\n@hartytp responds\r\n\r\nYes, but only when the switch is off, and only via the 24-bit ADC.\r\n\r\nMain cost is space: as @sbouhabib pointed out elsewhere, this is the largest component on BaseMod and fitting it on was actually quite challenging. If we remove it then we can make the layout a bit less tight.\r\n\r\nNot a huge deal, but it's not totally cost free so unless you really plan to use it then we should scrap it.\r\n-----------------\r\n\r\nMy comments.... \r\n\r\nAgreed that space occupied by the power detector design is huge. Especially because it involves impedance controlled traces. Design complexity due to the inclusion of the detector can only be described as very high. \r\n\r\n![image](https://user-images.githubusercontent.com/20543958/33576602-583f9b6a-d90e-11e7-8903-86fb9c934a07.png)\r\n\r\nIt also consists of 27 BOM items. AD8363 is about $7/ea and HMC349 switch is about $5. Component cost is not high. \r\n\r\n\r\n\r\n> I don't think it's actually that useful because:\r\n> It is read out by the 24-bit ADC which is very slow\r\n\r\nThe original intent to compensate for long-term drift. Not for fast feedback. As you point out the power can only be monitored when the RF output to the physics target is off (using HMC349 switch). This was never intended for fast feedback.\r\n\r\nAgreed that this is something that probably should have been culled from the original design. \n\n_Copied from original issue: sinara-hw/sinara#411_"},"comment":{"url":"https://api.github.com/repos/sinara-hw/BaseMod/issues/comments/447601089","html_url":"https://github.com/sinara-hw/BaseMod/issues/2#issuecomment-447601089","issue_url":"https://api.github.com/repos/sinara-hw/BaseMod/issues/2","id":447601089,"node_id":"MDEyOklzc3VlQ29tbWVudDQ0NzYwMTA4OQ==","user":{"login":"gkasprow","id":4325054,"node_id":"MDQ6VXNlcjQzMjUwNTQ=","avatar_url":"https://avatars3.githubusercontent.com/u/4325054?v=4","gravatar_id":"","url":"https://api.github.com/users/gkasprow","html_url":"https://github.com/gkasprow","followers_url":"https://api.github.com/users/gkasprow/followers","following_url":"https://api.github.com/users/gkasprow/following{/other_user}","gists_url":"https://api.github.com/users/gkasprow/gists{/gist_id}","starred_url":"https://api.github.com/users/gkasprow/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/gkasprow/subscriptions","organizations_url":"https://api.github.com/users/gkasprow/orgs","repos_url":"https://api.github.com/users/gkasprow/repos","events_url":"https://api.github.com/users/gkasprow/events{/privacy}","received_events_url":"https://api.github.com/users/gkasprow/received_events","type":"User","site_admin":false},"created_at":"2018-12-15T22:06:13Z","updated_at":"2018-12-15T22:06:13Z","author_association":"MEMBER","body":"We have much more space than in rev1. I can fit all we need easily"}}
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