Timeline for How do I design a DC-block cap without interfering with my filter?
Current License: CC BY-SA 4.0
15 events
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| Feb 2, 2019 at 18:01 | history | bumped | CommunityBot | This question has answers that may be good or bad; the system has marked it active so that they can be reviewed. | |
| Jun 6, 2018 at 19:06 | answer | added | Voltage Spike♦ | timeline score: 1 | |
| Jun 6, 2018 at 19:03 | comment | added | Reinderien | @aconcernedcitizen Maybe? The DC current flowing through the antenna would be very low: the varicap specsheet suggests that for room temperature it would be in the tens of pA. I'll have to think about that. | |
| Jun 6, 2018 at 19:00 | comment | added | a concerned citizen | Not RF guy either (so opinion only, I'm afraid), but could you use the loop antenna as not grounded, but connected to the supply and feeding the varicap? That way you only keep the output DC blocking cap. Not sure about the PIN diode, though... | |
| Jun 6, 2018 at 18:45 | comment | added | Reinderien | @Andyaka Added circuit diagram minus simulated elements. | |
| Jun 6, 2018 at 18:44 | history | edited | Reinderien | CC BY-SA 4.0 |
Added simplified circuit
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| Jun 6, 2018 at 15:31 | comment | added | Andy aka | Just show a schematic that is the bare bone components with no parasitics to muddle the mind. Showing a complex diagram with all information makes it difficult to decipher and the walk-thru is just not needed with a simple circuit as this should be. Make it easier for the guys who know about RF to understand. | |
| Jun 6, 2018 at 7:57 | history | tweeted | twitter.com/StackElectronix/status/1004270974706085888 | ||
| Jun 6, 2018 at 5:57 | comment | added | The Photon | My thoughts as not-a-real-rf-guy are 1. You're worried about a pass-band that's 40 dB down from the gain at your desired signal frquency 2. If that is a real issue, you may rather just use a separate high-pass filter stage to deal with it. 3. You're also going to need to worry about the effect of Cbp2 once you consider realistic loads on the circuit. | |
| Jun 6, 2018 at 3:39 | comment | added | analogsystemsrf | One useful theorem of matching and filtering networks is this: ALL POSSIBLE MODES of energy storage will be stimulated. Its your task to ensure only the frequencies you wish to resonate to be allowed to store energy. | |
| Jun 6, 2018 at 3:19 | comment | added | user105652 | Ok, now I see your predicament. The lack of comments means this has no easy solution, but some RF guru here will find something to work with. | |
| Jun 6, 2018 at 2:33 | comment | added | Reinderien | @Sparky256 I'm not sure what you mean by separate bands refusing to merge - I don't really want them to merge; I'd like a high-Q peak at either 3.33MHz +/- 10% (where the variation is managed by the varicap) if the lower range is enabled, or about 4.8-23MHz if the lower range is disabled. | |
| Jun 6, 2018 at 2:27 | comment | added | user105652 | Looks like a comb filter, which has equal band-gaps between frequencies. Would that be easier then 2 separate bands that refuse to merge? A single resonator would set the spacing, but you need an excitation oscillator to start. | |
| Jun 6, 2018 at 1:43 | history | edited | Reinderien | CC BY-SA 4.0 |
Term fix
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| Jun 6, 2018 at 1:36 | history | asked | Reinderien | CC BY-SA 4.0 |