Semiconductor Process
Understanding RF Semiconductor Processes
The semiconductor process determines what an MMIC can do. Each process provides specific transistor characteristics that define the achievable frequency, power, noise, and linearity performance. Selecting the right process is the first step in MMIC design.
RF Process Comparison
| Process | Frequency | Power | NF | Integration |
|---|---|---|---|---|
| GaAs pHEMT | DC-100 GHz | Moderate | Excellent | Moderate |
| GaN HEMT | DC-40 GHz | Excellent | Good | Low |
| SiGe BiCMOS | DC-60 GHz | Low | Good | High |
| InP HEMT | DC-300+ GHz | Low | Best | Low |
| CMOS | DC-60 GHz | Low | Fair | Highest |
Frequently Asked Questions
How do I choose a semiconductor process?
Based on requirements. Power amplifier: GaN. Low noise: GaAs pHEMT or InP. Maximum integration/lowest cost: CMOS or SiGe. Highest frequency (> 100 GHz): InP. Moderate frequency with good performance: GaAs.
Can CMOS compete with GaAs for RF?
CMOS is closing the gap for sub-6 GHz and even mmWave applications. Advanced CMOS nodes (7nm, 5nm) achieve adequate NF and gain for 28/39 GHz 5G. But GaAs/GaN still dominate for high power, very low noise, and frequencies above 40 GHz.
What is GaN-on-SiC vs GaN-on-Si?
GaN-on-SiC: SiC substrate provides excellent thermal conductivity (3.5x Si), enabling higher power density. Preferred for military and high-performance applications. GaN-on-Si: lower cost, larger wafers, adequate for moderate power. Growing in 5G base stations.