No difference in sensitivity levels between LDO and DCDC mode for nRF52832-CIAA (CSP package)?

[markus.wejrot]

We are devolping a module with nRF52832-CIAA (CSP package) and we are not satisfied with the sensitivity.

According to the nRF52832 Errata is the sensitivity level different depending on the voltage regulator mode (see 3.28 [91] RADIO: Radio performance using CSP package
in nRF52832 Errata, infocenter.nordicsemi.com/.../nRF52832_Rev_2_Errata_v1.1.pdf) between LDO and DCDC mode for nRF52832-CIAA (CSP package). 

But when testing different voltage regulator modes (DCDC and LDO mode) we can not measure 2 dB difference in sensitivity .
The measured sensitivities are -91dBm +/- 1dB (expected -91dBm to -92dBm in DCDC mode and -93dBm to -94dBm in LDO mode). The current increase as expected when changing from DCDC to LDO mode.

Should anything more be done except disabling DCDC mode via the DCDCEN register to improve sensitivity for nRF52832-CIAA?

[ketiljo]

Hi Markus

There should be a difference in sensitivity between the two modes. Have you measured the impedance into the matching network with the radio in RX mode? This should be as close to 50 ohm as possible,

 

cheers,

Ketil

[markus.wejrot]

Hi Ketil,

We measure the following impedances:

2400	2440	2480
53.8-j12.5	57.5-j15	60.8-j15.5

What it the input impedance in receive mode for nRF52832-CIAA?

[ketiljo]

Hi Markus

The ideal impedance is 50 ohm. I'd like to see it closer in RX mode. Try with a small shunt cap and see if you can reduce the imaginary part a bit.

cheers,

Ketil