Wideband balun having a single primary winding and multiple secondary windings

摘要

An RF transmitter capable of transmitting over a wide range of frequencies includes a mixer (96) a wideband high Q balun (97) a first driver amplifier (87) and a second driver amplifier (91). The balun has a single primary winding (98) and two secondary windings (99 100). A differential output of the mixer is coupled to the primary winding. A first of the two (99) secondary windings is coupled to drive the first driver amplifier (87). A second (100) of the two secondary windings is coupled to drive the second driver amplifier (91). One driver amplifier is used when transmitting at lower frequencies whereas the other driver amplifier is used when transmitting at higher frequencies. By appropriate sizing of the inductances of the secondary windings and by switching out one of the secondary windings with a switch (104) at certain times the balun is tunable to operate over the wide frequency range while having a high quality factor Q thereby facilitating reduced power consumption while simultaneously meeting performance requirements.