Ultra-low power reflection amplifier using tunnel diode for RFID applications

Abstract

To increase backscatter efficiency and communication range in RFID systems, we propose an ultra-low power reflection amplifier using a tunnel diode. We measured the input impedance of a tunnel diode and used a compact matching circuit to provide the desired input impedance at 890 MHz for the RFID UHF band. The proposed circuit is designed to be free from oscillations to avoid Signal to Noise Ratio (SNR) degradation. This reflection amplifier consumes 0.2 mW DC power at bias voltage of 200 mV, making it an ideal candidate to amplify backscattered electromagnetic field in RFID transceivers. The gain of the proposed reflection amplifier is 17 dB for the incident power of -30 dBm. The fabricated circuit size is 20×25 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> (0.06λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.075λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ) on a substrate with ε <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</sub> = 3 and h = 0.762 mm. The measurement and simulation are in a good agreement.