BALF-NRF01D3 Ultra Miniature Balun STMicroelectronics BALF-NRF01D3 Ultra Miniature Balun integrates a matching network in a monolithic glass substrate. The matching impedance for this balun is customized for the nRF51822-QFAAG0/GC/FA, nRF51822-QFABB0, and nRF51422-QFAAE0 RF transceivers. The BALF-NRF01D3 balun uses STMicroelectronics Integrated Passive Device (IPD) technology on a non-conductive glass substrate that optimizes RF performances.