A 304 to 337 GHz Push-Push Frequency Doubler with 6.8 dBm P_max using T-Junction Combining in 90 nm SiGe BiCMOS Technology

This paper presents a fully integrated 304 GHz to 337 GHz push-push frequency doubler achieving 6.8 dBm peak output power (P<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</inf>) at 317 GHz for wideband joint communication and sensing (JCAS) applications in the WR03 frequency band. The high output power is achieved by driving the frequency doubler with a 4-way power combined amplifier that achieves a saturated output power of 18 dBm at around 160 GHz. The driving amplifier combines the power of 4 parallel unit cell amplifiers using transmission line based T-junction networks, that are used for matching and low loss in-phase power combining, simultaneously. A maximum total conversion gain of 28.8 dB from first to second harmonic is achieved with a competitive maximum drain efficiency of 0.47 % and fundamental suppression of over 16 dBc within the 3 dB bandwidth. The test structure is fabricated in a 90 nm SiGe BiCMOS technology with f<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</inf> / f<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</inf> of 300 GHz / 500 GHz and consumes an area of 1 mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> including pads. Driven by the 4-way driving amplifier, it delivers saturated power in excess of 0 dBm over a bandwidth of 55 GHz from 293 GHz to 348 GHz. The competitive output power in the WR03 frequency range proves that SiGe BiCMOS technology is a cost-effective solution for future JCAS applications.