The MRFXF5716 balun from MiniRF is not a typical passive balun. By definition, a balun converts a balanced RF signal to single-ended and vice versa. The 75 Ω MRF5716 does this while covering a 40 to 1220 MHz bandwidth with minimal RF signal degradation: less than 0.8 dB insertion loss, ±0.5 dB amplitude match and 23 dB typical return loss.
The MRFXF5716 uniquely offers a DC bias tap that will carry 400 mA without saturating the magnetic core, a design element to improve the performance of a push-pull amplifier. The high current handling enables an amplifier to deliver higher output power with fewer distortion products, which has been demonstrated with a 12 V push-pull amplifier measuring 2 to 3 dB improved modulation error ratio. The balun will handle 2 W RF output power.
The MRFXF5716 has a pin to provide current to both legs of the RF amplifier output, eliminating the cost of RF bias choke components. This feature also simplifies the RF circuit layout and reduces the footprint on the printed circuit board, yielding additional cost savings. The MRFXF5716 operates from -40°C to +100°C and is assembled in a miniature surface-mount package measuring 0.150 in. x 0.150 in.
50 Ω and 2 GHz bandwidth versions of the balun will be available in the future.