Detector circuit for an RFID-device

A detector circuit being part of a Radio Frequency Identification (RFID) device, and comprising:

• a bias current generator circuit configured to generate an output bias current that is proportional to the square of a temperature-dependent input current;
• first and second Field-Effect Transistor (FET) devices;
• at least one of the first and the second FET devices being biased by means of the output bias current of the bias current generator circuit so that said at least one of the first and the second FET devices operates in a sub-threshold region;
• an incoming Radio Frequency (RF) signal being coupled into at least one of the first and the second FET devices;
• a current source configured to generate a variable threshold current;
• and
• a comparator configured to determine, based on the variable threshold current and the incoming RF signal, whether a value of the incoming RF signal exceeds a threshold value,
• wherein the first and the second FET devices are first and second n-channel metal-oxide-semiconductor (NMOS) transistors,
• wherein the bias current generator circuit comprises a band-gap generator,
• wherein each of a first NMOS transistor and a second NMOS transistor is diode-connected,
• wherein the first and the second NMOS transistors are connected in series, and
• wherein a third NMOS transistor is biased by a constant reference current.