A project to design and build a Low Noise Amplifier (LNA) and 1,090 MHz bandpass filter for receiving ADS‑B transmissions on a Software Defined Radio (SDR).
After seeing several LNA / filter projects on the internet, that were either a partial solution or very expensive, I decided to build my own.
If you are wanting to get into ADS‑B plane tracking the best total solution I have found so far is the FlightAware PiAware ADS‑B Ground Station using their FlightAware Pro Stick and FlightAware 1090MHz ADS‑B Antenna.
I already had a SDR that I wanted to use, but needed additional amplification and filtering due to my location.
I had found a small 80x25x25mm extruded aluminum box on Ebay that seemed the perfect size to house all the needed components, so I designed the board to fit that case. The board was designed using Eagle CAD Ver 7.7 as a 4‑layer board with all RF traces and components matched to 50 ohms.
Power is supplied by an USB cable with a nominal 5 volts DC. The USB power is filtered before the circuit board by a FB20021-4B-RC common mode wide-band choke. The 5 volt input is regulated to 3.3 VDC by U1, a MIC5253‑3.3YC5 in a Teeny™ SC-70–5 package. This regulator is capable of 100 mA output current and is optimized for Ultra-low output noise applications.
After the SMA input connector the first component inline is capacitor C14 a 100pF 25V NP0 in a 0402 package. This is the DC block for the antenna input. A BAV99 diode D1 after the capacitor provides some protection, before connecting to the input of a Mini-Circuits PSA4-5043+ LNA.
The Mini-Circuits PSA4-5043+ is a E‑PHEMT (Pseudomorphic High-Electron-Mobility Transistor) based Ultra-Low Noise MMIC Amplifier. Operating from 50 MHz to 4 GHz with a typical noise figure of 0.75 at 1,090 MHz, and a typical gain of 17 dB. The amplifier consumes 33 mA at 3V and is internally matched to 50 ohms. It is supplied in a super small SC-70 (SOT-343) MSL 1 package (MMM1362).
A Mini-Circuits TCBT-14+ Bias‑T after the LNA injects the regulated 3.3 volts into the output of the LNA to provide power for the amplifier, filters RF from the power supply, and also has a DC blocking capacitor for the RF output to the filter section.
The filter is a Mini-Circuits CBP-1090C+ 1,090 MHz bandpass filter in a MP1766 package. The CBP-1090C+ is a ceramic-coaxial-resonator based bandpass filter in a shielded package fabricated using SMT technology. This enables sharp rejection near the passband (1060 to 1120 MHz) and low insertion loss. The output of the filter connects to the output SMA connector.
The 4‑layer boards were fabricated by OSH-Park printed circuit board (PCB) service. OSH-Park LNA60 3V3 Case 1090MHz Filter Ver‑2.3 project page
Link for Eagle CAD V7.7 schematic and board files ZIP: LNA1090MHzFilter2.3
Test setup with a FlightAware Pro Stick mounted in a metal case with heatsink.