Ultra-Wideband Active Balun Topology and Its Implementation on SiGe BiCMOS Across DC-50 GHz

A new type of active baluns consisting of a common emitter (CE) amplifier with degenerative inductor and a common collector (CC) amplifier is proposed, analyzed and demonstrated using a 0.18-μm SiGe BiCMOS process. The parasitic neutralization and compensation techniques are used to keep the balun well balanced at very high frequencies and across an ultra-wide bandwidth. The active balun is particularly not affected by any components connected at its input or output ports, making it very attractive for integrating with other components and for system integration. The designed 0.18-μm SiGe BiCMOS active balun exhibits an amplitude imbalance lower than 1 dB and phase imbalance lower than 100 from dc to 50 GHz, and consumes a low dc power of only 14.4 mW from a dc power supply voltage of 1.8 V.