STMicroelectronics 2.4 GHz balun design for Nordic Semiconductor nRF51 and nRF24 series transceivers and SoCs

STMicroelectronics has developed an integrated 2.4 GHz balun design for Nordic Semiconductor’s nRF51 and nRF24 series transceivers and SoCs (systems-on-chip).

It eliminates the need for RF antenna matching circuitry comprising up to eight passive components (capacitors and inductors) and the interconnections between them.

The design incorporates a BAL-NRF01D3 integrated passive device (IPD) balun matching network in a single 1.0 x 1.5 mm flip-chip package. The IPD balun takes direct differential input from a Nordic nRF device and feeds directly out into a single-ended 50 Ω antenna. The nRF24 series devices require no further matching and harmonic suppression components. The nRF51 series devices require only a single 0.8 pF capacitor externally to the ST BAL-NRF01D3.

The high Q (antenna performance boosting) thin-film technology employed in the ST BAL-NRF01D3 also significantly improves RF performance and characteristics over the use of standard passive component matching. This includes: a +0.9 dB average output power improvement at 4 dBm; +1 dB better sensitivity at 1 Mbps on-air transmit speeds; 10 dB better LO (local oscillator) suppression; and -39.1 dBm 2nd harmonic suppression. The improved harmonic and LO suppression levels also promote simpler mandatory FCC/ETSI compliance testing and approvals.