RFGaN vs LDMOS: Technology Comparison
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This page dives into the differences between GaN (Gallium Nitride) and LDMOS (Laterally Diffused MOSFET) technologies. Let’s explore their characteristics and applications.
| Parameter | GaN | LDMOS |
|---|---|---|
| Full form | Gallium Nitride | Laterally Diffused MOSFET |
| Applications | • GaN on SiC (50V) provides high efficiency, power density and higher gain in smaller package • Used for broadband applications due to higher output impedance and lower Cds capacitance • Advantages: GaN transistors have small parasitic capacitance and hence they have easy wideband matching compare to LDMOS transistors of identical power level. | • LDMOS is used for cellular and broadcast narrowband applications due to high power and efficiency • LDMOS(50V) is used for <1.5 GHz applications while LDMOS (28V) is used for frequencies upto 4 GHz • Disadvantages: LDMOS transistor has large Cgs/Cds capacitance due to large peripheral in its design. This will limit the bandwidth. |
| Fmax (GHz) | 30 GHz for GaN (50V) | 22 GHz for LDMOS (28V) 15 GHz for LDMOS (50V) |
| Power Density (W/mm) | 5-10 for GaN (50V) | 0.8 for LDMOS (28V) 2 for LDMOS (50V) |
| Efficiency at P 1dB (%) | 70 for GaN (50V) | 60 for LDMOS (28V) <55 for LDMOS (50V) |
| Bandwidth (MHz) | 500-2500 for GaN (50V) | 100-400 for LDMOS (28V) 100-500 for LDMOS (50V) |
| Cds (pF/ W) | 1/4 smaller for GaN (50V) | 0.23 for LDMOS (28V) 1/2 smaller for LDMOS (50V) |
| Cgs (pF/ W) | 1/2 smaller for GaN (50V) | 0.94 for LDMOS (28V) 1/2 smaller for LDMOS (50V) |
Key Takeaways
- GaN: Excels in broadband applications requiring high efficiency and power density. Its smaller parasitic capacitance makes wideband matching easier. GaN is known to offer more power and performance.
- LDMOS: Well-suited for narrowband applications like cellular and broadcast, where high power and efficiency are crucial. LDMOS comes in at a lower price point, making it appealing for a wide range of applications. Its higher capacitance can limit bandwidth.
