kampianakis
Newbie level 4
Hi all,
I am currently building an RFID system in which i need a transistor for the communication front end. In principle the system achieves backscatter modulation by switching a single RF transistor, connected to the scattering antenna. The transistor’s gate is directly connected to a MCU output pin and its collector to a SMA antenna connector (Fig. 2). The transistor’s gate is either biased to a ‘low’ voltage level (0V) or a ‘high’ voltage level (3V). This way, the transistor acts as an open or closed switch, and the antenna-load reflection coefficient takes two distinct values Γi, i = 1, 2. In order to consume as less power as possible i need to utilize a MOSFET transistor as a switch. With a quick search I found numerous products capable for the job. However, most (if not all) are N-channel, depletion type MOSFETS, meaning that i, somehow have to produce a negative potential to the transistor gate. Taking under consideration that the reason why i use MOSFETS is to avoid consuming any power (apart from the leakage current which is on the order of <1uA), are you aware of either an enhancement mode RF transistor or a power-less trick in order to achieve Vgs < 0 without having a negative potential available in my circuitry?
Thank you in advance
Lefteris
I am currently building an RFID system in which i need a transistor for the communication front end. In principle the system achieves backscatter modulation by switching a single RF transistor, connected to the scattering antenna. The transistor’s gate is directly connected to a MCU output pin and its collector to a SMA antenna connector (Fig. 2). The transistor’s gate is either biased to a ‘low’ voltage level (0V) or a ‘high’ voltage level (3V). This way, the transistor acts as an open or closed switch, and the antenna-load reflection coefficient takes two distinct values Γi, i = 1, 2. In order to consume as less power as possible i need to utilize a MOSFET transistor as a switch. With a quick search I found numerous products capable for the job. However, most (if not all) are N-channel, depletion type MOSFETS, meaning that i, somehow have to produce a negative potential to the transistor gate. Taking under consideration that the reason why i use MOSFETS is to avoid consuming any power (apart from the leakage current which is on the order of <1uA), are you aware of either an enhancement mode RF transistor or a power-less trick in order to achieve Vgs < 0 without having a negative potential available in my circuitry?
Thank you in advance
Lefteris
