Activity for leroy105‭

Type	On...	Excerpt	Status	Date
Comment	Post #281226	High Q passives -- no real improvement. Within the margin of error in our reading in a chamber. (more)	—	over 3 years ago
Comment	Post #281274	Yep... There's an economic reason or semiconductor reason first and then the standard gets drafted... (more)	—	over 3 years ago
Comment	Post #281246	Yeah for sure in LiPos. If we a had semiconductor designer guy here, I'm sure there's some insight at that level as well. OP got dismissed as this being a stupid question and in reality it's really probably preety deep. It just happens to not be a solve an analog circuit type inquiry. (more)	—	over 3 years ago
Edit	Post #281247	Initial revision	—	over 3 years ago
Answer	—	A: Why are posts that users clearly approve of being closed? Definently agree. This original post hits a whole punch of EE topics. Sure, if the OP was an expert in consumer microwaves and WiFi theory and RF and FCC Compliance - they could write an epic post like the Lundin example. If they had background knowledge, I seriously doubt they would be posting th... (more)	—	over 3 years ago
Edit	Post #281246	Post edited:	—	over 3 years ago
Edit	Post #281246	Post edited:	—	over 3 years ago
Edit	Post #281246	Post edited:	—	over 3 years ago
Edit	Post #281246	Initial revision	—	over 3 years ago
Answer	—	A: Why 3.3V instead of 3V? Actually I think this is a really good question. It's kind of more historical though I guess (and I don't know the historical answer either, but from building products perspective I think this is probably the reason/s). 75V DC is a cut-off value for safety testing on products (OSHA / UL requi... (more)	—	over 3 years ago
Comment	Post #280791	Actually I think this is a really good question. It's kind of more historical though I guess (and I don't know the answer either). (more)	—	over 3 years ago
Comment	Post #281021	I'm all for pulling SE information off a for-profit-company's services (and I've learned a heck of lot on EE SE), but this post kind of proves the difficulties in moderation and the needs to include folks. I found EE SE super dogmatic; "don't discuss design"/"design comments too much, you are banis... (more)	—	over 3 years ago
Edit	Post #281226	Post edited:	—	over 3 years ago
Comment	Post #281165	C1 - 3.6pF, L1, 10nH, C2, 3.6pF -- was what the calculator I used said [really similar to your values]. I tweaked the capacitance and inductance bit in two other test runs and in both cases +0.4dB (in the wrong direction!). You could make a week long science experiment and do a bunch of iteration t... (more)	—	over 3 years ago
Comment	Post #281226	@ Andy aka - I'm ordering some high Q components to see if we can get that 12dB drop to increase a little more. I have some folders of some rando. low grade passives for tuning work. I did a few passes tweaking some values and the filter response is still not exactly what a calculator would say, bu... (more)	—	over 3 years ago
Comment	Post #281165	@Andy, I didn't get a perfect response from the filter calculator I used. Do you think that is most likely due to a not-perfect 50 ohm match on the board, so the filter calculations are off a bit? (more)	—	over 3 years ago
Comment	Post #281165	@Lundin - I've worked on a number of LoRa systems we have seen all kinds of over-limit harmonics in the past (never been tasked to filter one). LoRa transmit is usually 20+dBm + antenna gain, so you can get some pretty honking regulatory readings on the spurious emissions side. (more)	—	over 3 years ago
Edit	Post #281226	Post edited:	—	over 3 years ago
Edit	Post #281226	Initial revision	—	over 3 years ago
Answer	—	A: Filter RF Harmonics With Additional PI Network We got a copy of the hardware and took a first crack using a lowpass Chebyshev filter at 950MHz (radio transmits up to 930MHz). On the first pass, we got a .2dBm drop on the fundamental [margin of error in our test chamber] and a 12db drop on the most severe harmonic. I don't know if the Chebys... (more)	—	over 3 years ago
Comment	Post #281165	@Andy Aka -- I got the hardware in hand and implemented a Chebyshev using the PI network in front of the reference stack of matching components and filtering. 0.2dBm drop at the fundamental of 915MHz & 12 dB drop at the most severe 7GHz harmonic. That's going to be darn close to passing FCC limits... (more)	—	over 3 years ago
Comment	Post #281083	We care about the harmonics coming out of the product because they are over the FCC limits! There's no antenna switch, it's a reference design LoRa radio (there's a lump of passive components to tune to 50 ohms out of the chip, and then I've got an empty pi network now to fix these harmonics). I'... (more)	—	almost 4 years ago
Edit	Post #281083	Initial revision	—	almost 4 years ago
Question	—	Filter RF Harmonics With Additional PI Network I have a 900MHz radio with a reference design matching network. The radio feeds to a PCB antenna (PCB antenna hasn't been verified with a VNA, and may not be a great match; this is a project to now fix this system). There are over the limit harmonics from the 6th harmonic (5,400MHZ) to (8,100MHz... (more)	—	almost 4 years ago
Comment	Post #279886	I do lot of EMC testing, and agree with all these rules of thumbs, but specifically we are targetting the shield. The GND'ing is pretty much locked in place. I know much blood has spilt on the shield to GND plane discussion. (Also, bypass caps for ESD is a real thing...). We have a series 0402 fo... (more)	—	about 4 years ago
Edit	Post #279876	Post edited:	—	about 4 years ago
Edit	Post #279876	Initial revision	—	about 4 years ago
Question	—	ESD USB Shield Connection & Filtering I have a handheld ARM Cortex M based device, which has a USB input port. The product is battery powered and there is no metal chassis. We are going through CE testing, and are having ESD issues at 4kV contact to the USB shield with reproducibility under IEC 61000-4-2. On the data lines of th... (more)	—	about 4 years ago