# US 10,873,322 B2 · Detector circuit for an RFID-device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,873,322 B2 - Document ID: US10873322B2 - Status: Granted - Kind: B2 - Application number: 16/142,751 - Filed: 2018-09-26 - Published: 2020-03-26 - Granted: 2020-12-22 - Earliest claimed: 2018-09-26 - Assignees: EM Microelectronic-Marin SA - Applicants: EM Microelectronic-Marin S.A. - Inventors: Robert R Rotzoll; Kevin Scott Buescher - Web page: https://patentgrep.com/patent/US10873322B2 ## CPC - G06K 7/10009: {sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves} - H03K 3/011: Modifications of generator to compensate for variations in physical values, e.g. voltage, temperature {(to maintain energy constant H03K3/015)} - G05F 3/16: being semiconductor devices - G06K 7/10366: {the interrogation device being adapted for miscellaneous applications} - H03D 1/18: of semiconductor devices - H03K 3/012: Modifications of generator to improve response time or to decrease power consumption - H03K 5/24: the characteristic being amplitude - H03K 17/687: the devices being field-effect transistors - H03D 2200/0098: by compensating temperature induced variations - H03M 1/66: Digital/analogue converters ({H03M1/001 – } H03M1/10 take precedence) - G06K: GRAPHICAL DATA READING (image or video recognition or understanding G06V); PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS - H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M) - G05F: SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES - H03D: DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER (masers, lasers H01S; circuits capable of acting both as modulator and demodulator H03C; details applicable to both modulators and frequency-changers H03C; demodulating pulses H03K9/00; transforming types of pulse modulation H03K11/00; coding, decoding or code conversion, in general H03M; repeater stations H04B7/14; demodulators adapted for AC systems of digital information transmission H04L27/00; synchronous demodulators adapted for colour television H04N9/66) - H03M: CODING; DECODING; CODE CONVERSION IN GENERAL (using fluidic means F15C4/00; optical analogue/digital converters G02F7/00; coding, decoding or code conversion, specially adapted for particular applications, see the relevant subclasses, e.g. G01D, G01R, G06F, G06T, G09G, G10L, G11B, G11C, H04B, H04L, H04M, H04N; ciphering or deciphering for cryptography or other purposes involving the need for secrecy G09C) ## Abstract A detector circuit being part of a Radio Frequency Identification (RFID) device is provided, including: 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 is biased by means of the output bias current of the bias current generator circuit so that FET device(s) 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. ## Claims ### Claim 1 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. ### Claim 2 (depends on 1) The detector circuit according to claim 1, wherein the bias current generator circuit comprises five FET devices. ### Claim 3 (depends on 2) The detector circuit according to claim 2, wherein FET devices of the bias current generator circuit are n-channel metal-oxide-semiconductor (NMOS) transistors operating in the sub-threshold region. ### Claim 4 (depends on 1) The detector circuit according to claim 1, wherein the incoming RF signal is AC-coupled into the first NMOS transistor. ### Claim 5 (depends on 1) The detector circuit according to claim 1, further comprising a third NMOS transistor, arranged between the first NMOS transistor and a load device. ### Claim 6 (depends on 5) The detector circuit according to claim 5, the detector circuit further comprising a fourth NMOS transistor, arranged between the second NMOS transistor and the load device. ### Claim 7 (depends on 6) The detector circuit according to claim 6, wherein the current source configured to generate the variable threshold current is a current output digital-to-analogue converter (DAC) connected to the fourth NMOS transistor and to the load device. ### Claim 8 (depends on 6) The detector circuit according to claim 6, wherein the comparator configured to determine whether the value of the incoming RF signal exceeds the threshold value is connected to the fourth NMOS transistor and to the load device. ### Claim 9 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 RF signal is alternately AC-coupled into the first and the second NMOS transistors and the first and the second FET devices are alternately biased by means of the output bias current of the bias current generator circuit so that the first and the second FET devices operate in the sub-threshold region. ### Claim 10 (depends on 9) The detector circuit according to claim 9, wherein a bias is applied on the first and the second NMOS transistors at the same time the first and the second NMOS transistors receive the RF signal. ### Claim 11 (depends on 10) The detector circuit according to claim 10, wherein current of a current output digital-to-analogue converter (DAC) is alternated into a first and a second load.