“high performance RF capacitors”

RE: “high performance RF capacitors”

Håkon Alseth — Wed, 26 Feb 2014 10:56:04 GMT

Hi Simon,

As long as the 0402 caps are C0G/NP0 grade, they are within our requirements. Since the caps used are in the low pF-area (< 5.0 pF) and of 0402 size, the LC makes it resonante above 2.4GHz.

BR Håkon

RE: “high performance RF capacitors”

Simon — Tue, 25 Feb 2014 06:22:50 GMT

What self resonance frequency requirements need to be met for the RF circuitry caps?

Thanks.

RE: “high performance RF capacitors”

Håkon Alseth — Wed, 29 Jan 2014 16:13:34 GMT

Hi Simon,

Normal X7R grade caps will work, as they are not located in the RF matching circuitry (ANT1 and ANT2). They are only there to reduce noise on the different VDD lines.

Best regards Håkon

RE: “high performance RF capacitors”

Simon — Tue, 28 Jan 2014 05:30:43 GMT

Hi Håkon, thanks for that on DEC1 and AVDD. About the caps, will any X7R do for decoupling or do I have to ensure they are special RF caps in addition to the required X7R ? Some manufactures have RF series caps and usually the “SERIES RESONANCE VS. CAPACITANCE” is only expressed up to 1000MHz. So should I be concerned about this and looking at the RF series X7R for decoupling?

RE: “high performance RF capacitors”

Håkon Alseth — Mon, 27 Jan 2014 16:00:50 GMT

Hi Simon,

by "high performance chip inductor" these requirements have to be met:

For instance the Murata LQP15-series.

Decoupling caps should be the class that they are specified to be. Usually, this means X7R for "normal" decoupling, and NP0 (or C0G, which is the same thing) for RF and XOSC.
I believe it's stated as NP0 +/- 2% in the datasheet I have (v2.0)

DEC1: This is the decoupling pin for one of the internal regulators. This is the regulator for digital peripherals, such as UART/SPI/TWI/TIMERs etc.

AVDD is similar to VDD_NRF, but it's some added logic internally if you're running on DCDC. If you look at the LDO-power scheme, you can see that this pin is connected to VCC, and for DCDC-power scheme this is fed back to the DCDC-regulator.

Best regards Håkon