Vanchip Power Amplifier Selection Guide
Introduction
Selecting the right power amplifier is critical for RF system performance. This guide provides a systematic approach to choosing Vanchip PAs based on application requirements.
Frequency Band Selection
The first step in PA selection is identifying your target frequency bands:
- Low-band (600-900MHz): B5, B8, B12, B13, B20, B28 - Use VCNB series
- Mid-band (1.7-2.7GHz): B1, B3, B34, B39 - Use VC4G series
- High-band (3.3-5.0GHz): n77, n78, n79 - Use VC5G series
Output Power Requirements
Determine your required output power based on application:
- Power Class 2 (26dBm): Standard for smartphones and mobile devices
- Power Class 3 (23dBm): Suitable for IoT and lower-power applications
- Higher power: Infrastructure applications may require +30dBm
Efficiency Considerations
PA efficiency directly impacts battery life and thermal performance:
- Target PAE >40% for 5G applications
- Consider average efficiency, not just peak
- Evaluate efficiency at back-off power levels
Package Selection
Choose package based on size and thermal constraints:
- CSP 2.0×2.0mm: Minimum size for smartphones
- CSP 3.0×3.0mm: Better thermal performance
- QFN: Easier assembly and testing
Conclusion
Contact LiTong FAE for personalized recommendations based on your specific requirements.
💡 FAE Insights
⚠️ Common Pitfalls
- ✗ Selecting PA based only on frequency without considering modulation requirements
- ✗ Ignoring thermal constraints in small form factor designs
- ✗ Not accounting for antenna mismatch in efficiency calculations
📋 Customer Cases
Smartphone OEM
Mobile Devices
Challenge
Customer selected PA based only on frequency band, resulting in poor battery life due to low back-off efficiency.
Solution
Switched to Vanchip VC5778 with DPT support, optimized matching for broader efficiency curve, and implemented dynamic bias control.
Results
Battery life improved by 18% in 5G usage scenarios. PA efficiency at 18dBm increased from 25% to 35%.
Frequently Asked Questions
1. How do I choose between discrete PA and FEM?
The choice between discrete PA and FEM depends on your priorities: (1) FEM advantages - smaller size (60% less PCB area), guaranteed performance, faster time-to-market, fewer components; (2) Discrete advantages - lower cost, design flexibility, ability to optimize for specific requirements, easier debugging. For smartphones with severe space constraints, FEM is usually preferred. For cost-sensitive IoT or infrastructure with specific performance requirements, discrete may be better. Vanchip offers both options for most bands.
2. What is the difference between PAE and drain efficiency?
PAE (Power-Added Efficiency) and drain efficiency are two different metrics: (1) Drain efficiency = RF Output Power / DC Input Power, ignoring input drive power; (2) PAE = (RF Output - RF Input) / DC Input, accounting for drive power. PAE is more relevant for most applications because it reflects the true power gain of the PA. For high-gain PAs (>25dB), the difference is small. For low-gain PAs, drain efficiency can be significantly higher than PAE. Vanchip specifies PAE, which is the industry standard for handset PAs.