A 21-27GHz self-shielded 4-way power-combining PA balun

SiGe Radio Frequency ICs for Low-Power Portable Communication

“…A plot of the measured and simulated response of the power combining (i.e., output) balun is shown in Fig. 27, where excellent agreement is seen [67]. Self-shielding is used in this balun to minimize substrate losses despite the relatively high operating frequency.…”

“…18) with 0.9-dB loss for 21-27 GHz medium power (i.e, 20-dBm output) applications has been developed in a 0.18-m SiGe-BiCMOS technology [67]. Based on a four-way transformer combiner, the symmetrical design transforms a 50-output load to four equal 13-loads with only 3% load mismatch.…”

A 21-26-GHz SiGe bipolar power amplifier MMIC

“…Previous work on a power-combining balun prototype has shown that measurement and electromagnetic simulation for the self-shielded design are in good agreement [46]. Therefore, simulation can be used to investigate electrical behaviors of the combiner that cannot be measured directly.…”

“…The power-combining balun also provides a single-ended output connection. The self-shielded balun [46] described in Section IV realizes magnetic coupling in a single-turn design. The 15-dB gain requirement at the maximum output power is satisfied by using three stages of amplification.…”

“…The interconnect for the power amplifier design must feed the two differential amplifier groups with a total of 460 mA for small-signal, and 600-660 mA of DC current at maximum output power. The solution proposed in this work utilizes self-shielded monolithic transformers [46] to couple the common-base stages, as described in the following section. …”