Non-invasive analyte sensor with superheterodyne circuit
A non-invasive analyte sensor includes a receive side with a superheterodyne circuit. The superheterodyne circuit include a mixer with an input that is electrically connected to a receive antenna, and a radio frequency generator connected to another input of the mixer and that is configured to generate a radio frequency signal. The mixer outputs a signal that is based on a frequency of a signal received by the receive antenna and the frequency of the signal generated by the radio frequency generator.
1. A non-invasive analyte sensor system, comprising:
an antenna array having at least two antennas each of which is configured to emit and receive radio frequency electromagnetic waves;
a transmit circuit that is selectively electrically connectable to any one or more of the at least two antennas, the transmit circuit includes a first radio frequency signal generator that is configured to generate at least one transmit signal in a radio frequency range of the electromagnetic spectrum to be transmitted into a target by the one or more of the at least two antennas the transmit circuit is electrically connected to; and
a receive circuit that is selectively electrically connectable to any one or more of the at least two antennas; the receive circuit includes a mixer with a first input that is electrically connectable to the one or more of the at least two antennas the receive circuit is electrically connected to, and a second radio frequency generator connected to a second input of the mixer, the mixer is configured to generate a radio frequency output signal that is based on signals received via the first input and the second input, and the mixer includes an output that outputs the generated radio frequency output signal.
2. The non-invasive analyte sensor system of claim 1 , further comprising a calibration path between the transmit circuit and the receive circuit, and the calibration path bypasses the antenna array.
3. The non-invasive analyte sensor system of claim 1 , wherein the radio frequency signal generated by the second radio frequency generator has a frequency that is offset from a frequency of the at least one transmit signal.
4. The non-invasive analyte sensor system of claim 1 , further comprising a band pass filter connected to the output of the mixer.
5. The non-invasive analyte sensor system of claim 1 , further comprising a temperature sensor connected to the first radio frequency signal generator and/or a temperature sensor connected to the second radio frequency signal generator.
6. The non-invasive analyte sensor system of claim 1 , wherein the at least one analyte comprises glucose, alcohol, white blood cells, or luteinizing hormone.