A four stage cascoded class-E power amplifier based on a high voltage / high power technique (HiVP) technique has been designed and implemented. The amplifier is fabricated using four separate flanged LDMOS transistors. Drain voltage has been reduced to increase the maximum frequency of class-E operation mode and to reduce the maximum drain voltage swing to protect the transistor from breakdown. Measurement results show 69% power-added efficiency (PAE), 30.1 dB of gain and 51.8 W output power at 150 MHz. Index Terms -Aluminum Oxide, class-E, high voltage /high power (HiVP), power amplifiers, thermal management of electronics.