Terahertz sensors and related systems and methods
An active radio-frequency (RF) sensing technology for determining the relative and/or absolute state (e.g., position, velocity, and/or acceleration) of a target object (e.g., a person, a car, a truck a lamp post, a utility pole, a building) is described. The sensors described herein operate in the Terahertz band (300 GHz to 3 THz). An active RF sensing device comprises a substrate and first and second semiconductor dies mounted on the substrate. The first semiconductor die has an RF transmit antenna array integrated thereon, and the transmit antenna array comprises a first plurality of RF antennas configured to generate an RF signals having frequency content in the 300 GHz-3 THz band. The second semiconductor die has an RF receive antenna array integrated thereon, and the receive antenna array comprises a second plurality of RF antennas configured to receive RF signals having frequency content in the 300 GHz-3 THz band.
1 . A device, comprising:
a substrate;
signal generation circuitry mounted on the substrate;
a plurality of conductive traces patterned on the substrate and coupled to the signal generation circuitry, wherein the plurality of conductive traces form a power divider;
a first semiconductor die of a first semiconductor type, mounted on the substrate and coupled to the signal generation circuitry through the power divider, the first semiconductor die having:
frequency up-conversion circuitry configured to receive an input signal having a first frequency and to produce an output signal having a second frequency that is a multiple of the first frequency, wherein the second frequency is between 300 GHz and 3 THz; and
a radio-frequency (RF) transmit antenna array coupled to the frequency up-conversion circuitry and sized to transmit RF signals in a frequency band corresponding to the second frequency;
a second semiconductor die of a second semiconductor type, mounted on the substrate and coupled to the signal generation circuitry, the second semiconductor die having an RF receive antenna array thereon, wherein the first semiconductor type is a silicon-germanium semiconductor type and the second semiconductor type is not a silicon-germanium semiconductor type; and
processing circuitry coupled to the RF transmit antenna array and to the RF receive antenna array and configured to determine a distance between the device and a target object.
2 . The device of claim 1 , wherein the second semiconductor type is a III-V semiconductor type.
3 . The device of claim 2 , wherein the second semiconductor type is an indium phosphide (InP) semiconductor type.
4 . The device of claim 1 , wherein the second semiconductor type has a current gain cutoff frequency (f t ) between 0.3 THz and 1 THz.
5 . The device of claim 1 , wherein the second semiconductor type has a maximum oscillation frequency (f max ) between 0.7 THz and 1.5 THz.
6 . The device of claim 1 , further comprising transmit circuitry coupled to the RF transmit antenna array and configured to cause the RF transmit antenna array to transmit the RF signals with a power level in a range of 10 dBm-30 dBm in the frequency band.
7 . The device of claim 1 , wherein:
the frequency up-conversion circuitry comprises a plurality of frequency multipliers, and
the power divider is configured to provide a signal having a time-varying center frequency to one or more of the plurality of frequency multipliers.
8 . A device comprising:
a substrate;
signal generation circuitry mounted on the substrate;
a plurality of conductive traces patterned on the substrate, coupled to the signal generation circuitry, wherein the plurality of conductive traces form a power divider;
an indium phosphide (InP)-based die, mounted on the substrate and coupled to the signal generation circuitry through the power divider, the InP-based die having:
frequency up-conversion circuitry configured to receive an input signal having a first frequency and to produce an output signal having a second frequency that is a multiple of the first frequency, wherein the second frequency is between 300 GHz and 3 THz; and
a radio-frequency (RF) transmit antenna array coupled to the frequency up-conversion circuitry and is sized to transmit RF signals in a frequency band corresponding to the second frequency;
a silicon-based die, mounted on the substrate and coupled to the signal generation circuitry, the silicon-based die having an RF receive antenna array integrated thereon; and
processing circuitry coupled to the RF transmit antenna array and to the RF receive antenna array and configured to determine a distance between the device and a target object.
9 . The device of claim 8 , further comprising transmit circuitry coupled to the RF transmit antenna array and configured to cause the RF transmit antenna array to transmit the RF signals with a power level in a range of 10 dBm-30 dBm in the frequency band.
10 . The device of claim 8 , wherein the second frequency is between 650 GHz and 690 GHz.
11 . The device of claim 8 , wherein the frequency up-conversion circuitry comprises one or more diodes.
12 . The device of claim 8 , further comprising a harmonic mixer comprising a silicon-germanium (SiGe) heterojunction bipolar transistor (HBT), wherein the harmonic mixer is coupled to the RF receive antenna array.
13 . The device of claim 8 , wherein the RF transmit antenna array comprises between 4 and 128 antennas and the receive antenna array comprises between 32 and 1024 antennas.
14 . The device of claim 7 , wherein:
the plurality of frequency multipliers are coupled to respective antennas of the transmit RF antenna array, and
the power divider is configured to cause the antennas of the RF transmit antenna array to transmit the RF signal in phase with respect to one another.
15 . The device of claim 14 , wherein the conductive traces forming the power divider comprise lengths selected to cause the antennas of the RF transmit antenna array to transmit the RF signals in phase with respect to one another.
16 . The device of claim 8 , wherein:
the frequency up-conversion circuitry comprises a plurality of frequency multipliers, and
the power divider is configured to provide a signal having a time-varying center frequency to one or more of the plurality of frequency multipliers.
17 . The device of claim 16 , wherein:
the plurality of frequency multipliers are coupled to respective antennas of the transmit RF antenna array, and
the power divider is configured to cause the antennas of the RF transmit antenna array to transmit the transmit RF signal in phase with respect to one another.
18 . The device of claim 17 , wherein the conductive traces forming the power divider comprise lengths selected to cause the antennas of the RF transmit antenna array to transmit the transmit RF signal in phase with respect to one another.