E-band communication is allocated to the frequency bands of 71-76 and 81-86GHz. Radio-frequency (RF) front-end components for E-band communication have been realized using compound semiconductor technology. To realize a CMOS LNA for E-band communication, we propose a gain-boosted cascode amplifier (GBCA) stage that simultaneously provides high gain and stability. Designing an LNA from scratch requires considerable time because the tuning of matching networks with consideration of the parasitic elements is complicated. In this paper, we model the characteristics of devices including the effects of their parasitic elements. Using these models, an optimizer can estimate the characteristic of a designed LNA precisely without electromagnetic simulations and gives us the design values of an LNA when the layout constraint is ignored. Starting from the values, a four-stage LNA with a GBCA stage is designed very easily even though the layout constraint is considered and fabricated by a 65nm LP CMOS process. The fabricated LNA is measured, and it is confirmed that it achieves 18.5GHz bandwidth and over 24.3dB gain with 50.6mW power consumption. This is the first LNA to achieve a gain bandwidth of over 300GHz in the E-band among the LNAs utilizing any kind of semiconductor technologies. In this paper, we have proved that CMOS technology, which is suitable for baseband and digital circuitry, is applicable to a communication system covering the entire E-band.