What Is the Best LNA for Your GPS Receiver?


The Global Positioning System (GPS) has become an integral part of our modern world, providing precise navigation information for applications such as cellular, automotive, military, surveying, and wearable electronics.
For those GPS applications demanding the absolute lowest noise amplifier performance, Guerrilla RF offers GRF2071 and its automotive-qualified variant GRF2071W. These devices deliver an industry-leading combination of noise figure (NF), gain, linearity and bandwidth.


The vector network analyzer (VNA) screen shot shows s-parameter performance of the GRF2071 / 2071W evaluation board with a tune bandwidth that exceeds the full range of GPS frequencies defined by L5 at 1176.45 MHz and L1 at 1575.42 MHz.



The table below highlights the measured evaluation board performance with the L1 to L5 tune.



Here are the main takeaways:


NF: Note that the extremely low NF values of 0.38 to 0.39 dB include the small losses (roughly 0.05 dB) associated with the evaluation board input SMA connector. De-embedded NF values are thus in the 0.34 dB range, making this the industry’s lowest NF solution for this band.


Gain: The gain values in the 20 to 22.5 range combine with the ultra-low NF to enable GPS receivers with the absolute lowest possible cascaded NF. Furthermore, the application schematic and matching values were also chosen to ensure unconditional stability.


Biasing: Biasing for most of Guerrilla RF’s pHEMT devices is extremely flexible, and GRF2071 / 2071W are no exception. Vdd can range from 2.7 to 5.0 volts with essentially no change to the device gain or NF. The device quiescent current (Iddq) can be adjusted over a typical range of 20 to 80 mA with only minimal NF degradation as the device current drops below 35 mA. Note that the device 1 dB compression point (P1dB) is more closely tied to Vdd than to Iddq, while just the opposite is true for the third-order intercept (IP3) performance.


Matching: The GRF2071 / 2071W matching performance shown in the VNA screen shot was achieved on the standard evaluation board with only nine external passive components. While care must be taken to ensure that the components on the LNA input are high-Q to optimize NF performance, the Guerrilla RF applications team achieves excellent results using low-cost GJM-series capacitors and LQG-series inductors from Murata with comparable substitutions posing no performance issues.


GRF2071 / 2071W are in full production using our standard  2.0 x 2.0 mm DFN-6 plastic package. Tuned evaluation boards and samples are available now. 
Regardless of your technical requirements, Guerrilla RF is committed to providing the high performance RF solutions and applications support necessary to make your product a success.


For more information, contact your local Brennan Associates representative.