STMicroelectronics, BAL-CC1101-01D3, Signal Magnetic Transformer, RF Transformer

 BAL-CC1101: 50 Ohm 1.9 dB Nominal Input / Conjugate Match Balun - Flip-Chip-4

https://www.futureelectronics.com/p/passives--transformers--signal-magnetic-transformers--digital/bal-cc1101-01d3-stmicroelectronics-3081903