20 MHz carrier frequency AM receiver in flexible a-IGZO TFT technology with textile antennas

This paper presents an AM receiver implemented in a flexible a-IGZO TFT technology. The circuit consists of a four-stage cascode amplifier at the RF input, a detector based on a source follower, and a common-source circuit for the baseband amplification. The measured conversion gain is very flat against frequency and exceeds 15 dB for carrier frequencies ranging from 2 to 20 MHz, which covers a relevant portion of the shortwave radio band. The 3 dB-bandwidth of the baseband signal ranges from 400 Hz to 10 kHz: this is comparable to the so-called voice band and is suitable to low-rate data communications. Additionally, the AM receiver is tested in combination with two textile antennas. The flexible a-IGZO receiver successfully detected the baseband signal through the textile antennas, demonstrating for the first time wireless transmission for this class of technologies.