GaN: a breakthrough technology

 

If the results of independent market research are fulfilled, sales of GaN products will exceed US$300 million in 2014. Only through the production of GaN by mainstream semiconductor companies (NXP is the leader) can this prediction be achieved. So, what exactly are GaN and RF power applications? In short, in most applications, GaN further improves efficiency and power density performance compared to Si LDMOS. This can be quantified in Johnson's figure of merit (FoM)-combining significant RF performance variables with Si equal to 1 as the baseline, resulting in a FoM of 324 for GaN. Generally speaking, another commonly used RF composite material, GaA, has a FoM of 1.44. In a word, GaN truly represents a breakthrough technology.

Bias

 

GaN products are called high electron mobility transistors (HEMT). This name captures an essential advantage of GaN: high electron drift speed. These transistors are depletion mode devices. Such devices are normally open and do not require gate bias. A negative gate bias is required to turn off the transistor. This bias is not provided directly, but at NXP, we provide solutions rather than just components, because proven bias circuits are already available and provide continuous application support throughout the life of the product.

high temperature

 

The greater advantage of GaN is that it has an extremely strong structure that can withstand extremely high temperatures. NXP's GaN transistors can specify a maximum temperature of 250 °C, compared to 225 °C for Si LDMOS. In such a high temperature environment, packaging technology that can make full use of this feature is even more needed. Therefore, customers will be the beneficiaries of NXP’s 30 years of experience in the field of RF power products. Our industrial base can provide customers with excellent product reliability, cost and a highly confident supply chain, which can supply GaN. This is the only business. As we said, GaN has therefore become mainstream.

The first generation of NXP GaN products

 

The first generation of NXP GaN products will be unique broadband amplifiers suitable for applications requiring high RF performance at various frequencies up to 3.5 GHz. NXP's first-generation GaN process is specifically designed for products that work under a 50V supply voltage, which can achieve first-class efficiency and linearity. Such products will use industry standard package sizes, allowing customers to use NXP products in existing designs without changing the mechanical design. NXP's new generation of GaN devices will be super efficient, bringing performance breakthroughs to the largest RF power device segment-cellular base stations. In turn, this technology breaks the linear amplifier topology with the concept of a switch mode power amplifier (SMPA). NXP is committed to making full use of the technology in the entire product range, which will also make the products suitable for higher frequency applications up to 10 GHz.