A THz Pulse Radiator Based on PIN Diode Reverse Recovery
The project produced a unique broadband oscillator-free THz pulse generation and radiation based on direct digital-to-impulse architecture. Based on this architecture, we designed and fabricated a broadband 0.03-1.1 THz signal generation and radiation chip.
The repetition rate of the generated pulses is programmable using the input trigger, which can be tuned to as high as 10.5 GHz. The power consumption of the driver stage is 20 mW at 5.5 GHz repetition-rate. An on-chip slot bow-tie antenna is employed for radiating the THz pulses with a total efficiency above 60% over the band of radiation.
The spectrum of the radiated pulses was measured from 320 GHz up to 1.1 THz using the VDI SAX and the Keysight N9030A PXA signal analyzer. This work demonstrates higher radiation power at frequencies above 300 GHz, a flatter average ERIP spectrum, and lower power consumption compared to the state of the art.
A CMOS Impulse Detector with 77 GHZ Center Frequency
An injection-locked picosecond pulse detector is implemented in 65-nm CMOS technology. An on-chip slot planar inverted cone antenna receives picosecond pulses with a center frequency of 77 GHz and feeds the signal to a low-noise amplifier. A three-stage injection-locked frequency divider is used to lock the output signal to the 9.6-GHz repetition rate with an effective locking range of 142 MHz and a timing jitter of 0.29 psrms.
A CMOS impulse detector with a center frequency of 77 GHz is presented to achieve low-jitter interchip wireless time transfer. A wireless time transfer test with two impulse detector chips demonstrates that a low-jitter 9.5-GHz clock is distributed among widely spaced nodes in a large-aperture array.
The impulse detector, which includes an on-chip slot PICA, is based on a three-stage divide-by-8 ILFD. It is shown that a three-stage divider has better input sensitivity than a single-stage divide-by-8 divider. The output of the receiver is locked to the input repetition rate with a rms jitter of 0.29 ps.
The injection-locked detector is utilized in a wireless time transfer setup to demonstrate its application in widely spaced synchronized distributed arrays. This fully integrated system consumes 42 mW from a 1.3-V supply and occupies a total area of 0.9 mm2, including the on-chip antenna and the pads.
THz Micro-Doppler Measurements Based On A Silicon-Based Picosecond Pulse Radiator
In our research, a custom picosecond pulse radiator is used to demonstrate the micro-Doppler phenomenon in the Terahertz (THz) regime. In the micro-Doppler effect, the periodic movement of radar targets modulates the frequency of the electromagnetic waves reflected from their surface. The modulation depth is dependent on the intensity of the vibrations and the carrier frequency. Therefore, using carrier tones in the THz regime enables detection of weak micro-Doppler signatures.
In this experiment, sound vibrations with frequency of 50 to 700 Hz were used to modulate a 395.2 GHz carrier signal produced by a digital-to-impulse (D2I) silicon chip.
Results included a ten-second music track, a chirp sound, and multiple frequency tones were produced by a speaker and then were reconstructed through the micro-Doppler effect. The sound waves were recovered via frequency demodulation at the receiver.
Fully Integrated 30-to-160GHz Coherent Detector with a Broadband Frequency Comb in 65nm CMOS
A novel 30-to-160GHz coherent detector is demonstrated in 65nm CMOS that uses an on-chip frequency comb as its reference.
The frequency comb is locked to an external sub-The tunable comb is used as a frequency ruler to downconvert mm-wave frequency tones to intermediate frequencies between 10 MHz and 1.9 GHz. A heterodyne FET detector mixes the received signal with the on-chip frequency comb. An on-chip elliptical antenna with a metasurface bottom layer receives the radiated signal and feeds it to the source of the heterodyne detector. This chip consumes 34 mW from a 1.2V power supply.
Measurement results show a 2-Hz line width on the detected tones, which sets the minimum detection resolution. This detector can coherently detect any frequency tone from 30 to 160 GHz with a resolution that is only limited to the line width while consuming a low power consumption. Therefore, this chip can be utilized in high-resolution mm-wave sensing and spectroscopy applications. Integrated systems based on the presented comb generation and heterodyne detection techniques demonstrate strong potential in developing broadband coherent detectors in the mm-wave/THz regime.
Broadband Spectroscopy of Materials with an Integrated Comb-Based Millimeter-Wave Detector
A miniaturized broadband spectroscopic sensor using a fully integrated millimeter-wave detector is presented. The detector chip generates a frequency comb with a tunable spacing as a reference to downconvert received signals. By tuning the comb spacing, the detector can detect frequency tones from 50 GHz to 155 GHz with a resolution only limited to the linewidth of comb tones. A spectroscopy setup including the detector and four sheets made of different materials is implemented to characterize the frequency response of materials in this frequency range.
Broadband spectroscopy of four objects made of different materials is demonstrated from 50 GHz to 155 GHz with a fully integrated comb-based mm-wave detector. It is shown that each object exhibits a unique response which can help us in identifying unknown objects using mm-wave frequency combs.