History of LDMOS

LDMOS was first reported in the 1960s, while LDMOS was first reported in 1969 by “Tarui et al” from the electrotechnical laboratory. Between 1977 and 1983, Hitachi was the only LDMOS manufacturer. It was used as an audio power amplifier in applications like music, public address systems, HH electronics, and Ashley audio during that period.

For RF applications, LDMOS was introduced in the 1970s by “Caught et al.” However, it wasn’t until the early 1990s RF LDMOS for wireless cellular networks replaced RF bipolar transistors because RF LDMOS provides better efficiency, gain, and linearity, all with lower costs.

After the introduction of 2G mobile networks, LDMOS was the most widely used power amplifier. They are further used in 3G mobile networks. RF LDMOS were the dominant RF power amplifiers in broadcasting, radar, cellular base stations, scientific, medical band, and industrial applications. Since then, LDMOS has greatly influenced most of the world’s data traffic and cellular voice.

When used in 3G and 4G (LTE) networks, RF power amplifiers based on single LDMOS produced low efficiencies in the Mid-2000s due to higher peaks to the average power of the modulation schemes and OFDMA and CDMA access techniques. So, in 2006, the efficiency of LDMOS was increased using techniques like envelope tracking and Doherty topologies.

Since 2011, RF LDMOS has been the dominant technology used in high-power RF power amplifiers for frequencies from 1MHz to more than 3.5GHz and for cellular infrastructure. As of 2018, LDMOS is the standard for power amplifiers in 4G and 5G mobile networks.