Beyond-$f_{\mathrm{T}}$ Operation of Mixer Circuits Based on Organic Thin-Film Transistors for Wireless Receivers at 13.56 MHz

In this paper, beyond-<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$f_{\mathrm{T}}$</tex> operation of mixer circuits fabricated using flexible organic thin-film transistors is investigated up to the ISM band of 13.56 MHz, normally used for RF identification (RFID) purposes, in order to show the potential of the low-complexity technology to provide pathways to flexible, low-cost wireless communication. For this sake, two passive frequency mixer circuits were designed, a double balanced mixer and a 2x subharmonic mixer. The designed mixer circuits are experimentally evaluated to assess their performance up to 13.56 MHz. At the target frequency, the double-balanced mixer was able to provide voltage conversion gain up to 4 dB at an intermediate frequency of 1 kHz, an input referred 1dB compression point of 3.5 dBV, and an LO to IF isolation of 76 dB. The 2x subharmonic mixer showed a conversion-voltage loss of 17.5 dB at an intermediate frequency of 1 kHz, an input-referred 1dB compression point of −1.5 dBV, and an LO to IF isolation of −70 dB.