The reason for small input and output capacitance values is to limit surge current on power up. The chip in that thing is so small you need a microscope to see it. The actual line widths of the traces are far less than the width of a cat hair! Micro-fuses!
If you must operate it at a variable voltage, either put in a voltage regulator, or a constant current source on the supply line. Which can be as simple as a jfet and a resistor (or simply a well selected jfet).
I dunno - I reached back to my engineering past and thought the resistor on the supply line was for decoupling - maybe that is not a thing at those frequencies.
I am guessing they used 100 nF to get better LF response (and they are cheap and plentiful because that is such a common value compared to the 470 pF). The chip itself is fine to DC, with the sub 1nF coupling caps its low frequency corner will be around 6-7 MHz. I got some of these boards off amazon and they were stuffed with 2k2 resistors instead of 220 ohm! Easy fix, but explained the large number of comments saying they didn't work. I left a review to explain the situation, but somewhere out there at least one entire batch of these things was assembled incorrectly. I don't really have a problem with using the dropping resistor, the gain and match variation with supply voltage is fairly modest and the resistor is approximately a current source - certainly a cheaper solution than a linear regulator and no less efficient, also lets you adjust the gain with the supply voltage which might be considered a feature. The mismatch isn't too bad, and you have gain to burn so you can always put pads each side - although that would hurt the noise figure a bit, it isn't exactly a LNA in modern terms despite what the datasheet says with > 3 dB NF.
I got to rework a project I built and was proud of. An audio circuit. The original builder used an obscure 12V battery to power it. I said forget that bother and built a regulated supply. The circuit has so much gain that you have low level hum issues regardless of filtering and regulation. So I have to modify it back to run on battery power but I will use a rechargeable battery pack rather than have to tear it apart to change dead batts. My mistake.
![BLACK BAG - Official Trailer [HD] - Only in Theaters March 14](http://i.ytimg.com/vi/Du0Xp8WX_7I/mqdefault.jpg)
Those desoldering tweezers sure come in handy! I'm feeling a need to have one on my bench after your review and seeing them used "in anger".
Make mistakes, break parts, release the magic smoke. It's how humans learn!
True!
RUclips is the best free school on this planet. It's just hard to remember when to go to class.
The reason for small input and output capacitance values is to limit surge current on power up. The chip in that thing is so small you need a microscope to see it. The actual line widths of the traces are far less than the width of a cat hair! Micro-fuses!
If you must operate it at a variable voltage, either put in a voltage regulator, or a constant current source on the supply line. Which can be as simple as a jfet and a resistor (or simply a well selected jfet).
I dunno - I reached back to my engineering past and thought the resistor on the supply line was for decoupling - maybe that is not a thing at those frequencies.
It's very instructive to see rework. Consider revisiting former projects. So many interesting builds!
He didn't make any mistakes, he was just testing us.
I am guessing they used 100 nF to get better LF response (and they are cheap and plentiful because that is such a common value compared to the 470 pF). The chip itself is fine to DC, with the sub 1nF coupling caps its low frequency corner will be around 6-7 MHz. I got some of these boards off amazon and they were stuffed with 2k2 resistors instead of 220 ohm! Easy fix, but explained the large number of comments saying they didn't work. I left a review to explain the situation, but somewhere out there at least one entire batch of these things was assembled incorrectly. I don't really have a problem with using the dropping resistor, the gain and match variation with supply voltage is fairly modest and the resistor is approximately a current source - certainly a cheaper solution than a linear regulator and no less efficient, also lets you adjust the gain with the supply voltage which might be considered a feature. The mismatch isn't too bad, and you have gain to burn so you can always put pads each side - although that would hurt the noise figure a bit, it isn't exactly a LNA in modern terms despite what the datasheet says with > 3 dB NF.
That SA trace sure looks better!
Everybody makes mistakes. A given.
I got to rework a project I built and was proud of. An audio circuit. The original builder used an obscure 12V battery to power it. I said forget that bother and built a regulated supply. The circuit has so much gain that you have low level hum issues regardless of filtering and regulation. So I have to modify it back to run on battery power but I will use a rechargeable battery pack rather than have to tear it apart to change dead batts. My mistake.
Such a nice branded notepad!
If you don't mind me asking, what desoldering tweezers are you using?
ruclips.net/video/iMLJKmgIBb4/видео.html
I don't know! This might drive me to the cooking channel.
The right season to be in the kitchen
Great debugging job
Is that an actual NXP part on the board? Maybe it's some generic MMIC that sorta matches the NXP pin-out and operating specs?
I'm convinced it is a real part
Nice!
you live long enough and you learn to be ok making mistakes
if not, get used to not "being ok" lol
Is it common to pronounce pF as "puff"? sounds funny
Old term us grey beards still use.
Have some regulators Need more of course
😊
✌