Among the mm-wave frequency bands, E-band is considered to have great potential for next-generation wireless communication due to its wide available bandwidth. One of the well-known challenges for mm-wave circuit in CMOS is to design a power amplifier (PA) with relatively high output power and enhanced power-added efficiency (PAE) at both saturated output power (Psat) and power back-off (PBO) levels. Especially for high-frequency band. Several innovative PA design approaches have been presented to address the issue in recent years. Most of them are based on a Doherty concept [1]–[2]. However, most reported Doherty PAs are either intrinsically narrow-band or only tunable over several bands with considerable nonlinearity and amplitude/phasing tuning. Recently, a new concept has been introduced, namely the load-modulated balanced amplifier (LMBA) [3], to address the narrow bandwidth of traditional Doherty PAs.