Truly Balanced K-Band Push-Push Frequency Doubler

This paper presents a truly balanced push-push frequency doubler. The novel concept is based on two lumped quadrature couplers that provide a truly balanced signaling for two doubler cells. As a consequence, the output signal is inherently balanced and a lossy output transformer can be avoided. Hence, higher output power and efficiency can be achieved. As a proof of concept, a K-band doubler is implemented in a 65 nm CMOS technology. At 0 dBm input power, the circuit delivers 5 dBm output power with more than 6 % PAE. The chip draws 26 mA from a 1.2 V supply and the total chip area is 0.85×0.55 mnr
²
. The fundamental suppression is around 44 dBc. To the best of the authors knowledge, this is the first fully balanced push-push doubler and the achieved results exceed state-of-the-art performance. The concept is applicable to other technologies and frequencies as well.