Are there any rules of thumb? Like "every chip needs a 100nF as close as possible", or something like this?
And what would you consider as "close" to the chip? Is 1in of wire/copper still "close"?
Poor power supply can lead to poor radio performance especially if the supply voltage is not kept withintolerance or is excessively noisy. To help reduce noise a 1uF and 8.2pF capacitor are recommended to beplaced as near to pin1 on the PCB as possible. If using a switching regulator for your power supply, switchingfrequencies above 500kHz are preferred. Power supply ripple should be limited to a maximum 250mV peak topeak.
take the attiny85, with no capacitor, it runs.... But an attiny85 at 8mhz, is not exactly high speed switching either....