VC5778
High-efficiency 5G NR power amplifier for n77/n78 bands (3.3-4.2GHz) with 26dBm output power and 42% PAE.
Product Overview
Description
The VC5778 is a high-performance 5G NR power amplifier designed for n77 and n78 frequency bands covering 3.3-4.2GHz.
Featuring advanced InGaP HBT technology, this PA delivers 26dBm output power with industry-leading 42% power-added efficiency.
Optimized for 5G NR 100MHz bandwidth signals, it maintains excellent linearity with EVM < 2.5% and ACLR < -40dBc.
Product Series
VC
Primary Application
5G smartphones
Key Features
- 5G NR n77/n78 band coverage
- High efficiency 42% PAE
- Excellent linearity for 100MHz BW
- Integrated power detector
- MIPI RFFE 2.0 control interface
- Compact CSP package
Specifications
| Frequency Range | 3.3 - 4.2 GHz |
|---|---|
| Output Power | 26 dBm |
| PAE | 42% |
| Gain | 26 dB |
| EVM | < 2.5% |
| ACLR | < -40 dBc |
| Supply Voltage | 3.4 V |
| Package | CSP 2.0×2.0 mm |
Applications
5G smartphones
Electronic system design
5G CPE devices
Electronic system design
Mobile broadband
Electronic system design
Fixed wireless access
Electronic system design
FAE Expert Insights
"The VC5778 is Vanchip's leading position in 5G PA technology. In my experience supporting multiple 5G smartphone projects, this PA consistently delivers excellent performance across temperature and voltage variations. The 42% PAE is genuinely impressive for high-band operation, helping our customers achieve competitive battery life. I particularly recommend the integrated power detector feature, which simplifies closed-loop power control design. For 5G NR designs requiring n77/n78 coverage, this is my go-to recommendation."
Industry-leading 42% PAE for 5G high-band applications
— Michael Zhang, BeiLuo
Frequently Asked Questions
What is the recommended PCB layout for VC5778?
For optimal VC5778 performance, follow these PCB layout guidelines: (1) Use controlled impedance 50Ω transmission lines for RF input/output; (2) Place decoupling capacitors (100pF, 1nF, 10μF) close to VCC pins; (3) Provide adequate ground vias around the PA for thermal dissipation; (4) Keep RF traces as short as possible to minimize losses; (5) Use multi-layer PCB with dedicated ground plane; (6) Follow the reference layout in the datasheet for matching network placement. Proper layout is critical for achieving specified efficiency and linearity performance.
Download the VC5778 application note for detailed layout recommendations and reference designs.
How do I bias the VC5778 for different power modes?
The VC5778 supports multiple bias modes controlled via MIPI RFFE interface: (1) High-power mode - for maximum output power at 26dBm, use default bias settings; (2) Mid-power mode - for 20-23dBm operation, reduce bias current by 20% to improve efficiency; (3) Low-power mode - for <20dBm, use deep bias reduction for maximum battery life; (4) Bypass mode - for receive operation, disable PA to minimize current consumption. The MIPI interface allows dynamic bias switching within 10μs, enabling real-time power optimization based on link conditions.
Implement dynamic bias control in your baseband software for optimal efficiency across operating conditions.
What thermal management is required for VC5778?
The VC5778 has a maximum junction temperature of 150°C. Thermal management recommendations: (1) Ensure adequate copper area on PCB for heat spreading - minimum 100mm² ground copper recommended; (2) Use thermal vias (0.3mm diameter, 1.0mm pitch) under the package paddle; (3) For continuous high-power operation, consider adding thermal interface material to chassis; (4) Monitor die temperature via internal thermal sensor and implement thermal throttling if needed; (5) At 26dBm CW output, typical junction temperature rise is 25-30°C above ambient with proper PCB design.
Perform thermal simulation for your specific PCB design and operating conditions.
Can VC5778 support 5G carrier aggregation?
Yes, the VC5778 fully supports 5G NR carrier aggregation: (1) Intra-band CA - supports contiguous and non-contiguous CA within n77 or n78; (2) Inter-band CA - can be combined with other Vanchip PAs for n77+n78 CA; (3) Up to 100MHz component carrier bandwidth; (4) Supports up to 3 CA combinations with total aggregated bandwidth up to 200MHz; (5) Maintains linearity specifications (EVM < 3%) under CA operation. For CA applications, ensure adequate power supply decoupling and consider thermal implications of higher average power.
Contact FAE for CA-specific reference designs and matching network optimization.
What is the typical application circuit for VC5778?
A typical VC5778 application circuit includes: (1) Input matching network - 2-element LC matching for 50Ω to optimal source impedance; (2) Output matching network - 3-element matching for optimal load impedance to 50Ω antenna; (3) Bias circuit - decoupling capacitors and MIPI RFFE interface; (4) Power detector - integrated detector with external filter capacitor; (5) Directional coupler (optional) - for closed-loop power control. The complete schematic and BOM are available in the application note. Total external component count is typically 12-15 passive components.
Request the VC5778 reference design package including schematic, BOM, and PCB layout files.