Terahertz (THz) communication is a promising technique for chip-to-chip communication and wireless personal area networks. In this paper, we present an experimental study and design to realize such THz communication systems. We develop two different chip sets for on-off-keying (OOK) modulation based THz transceivers which include carrier generators, modulators, THz amplifiers, and baseband amplifiers. Specifically, the first chip set integrates the circuit blocks for the OOK modulation without the THz amplifier for short-range communication. In addition, the second chip set design includes the THz amplifier modules to extend the coverage of transmission. For these two chip sets, we experimentally demonstrate the feasibility of the wireless communication at THz frequency bands and assess performance using the bit error rate (BER) analysis. We estimate the BER by calculating the signal-to-noise ratio (SNR) based on the eye diagram and compare with actual BER measurements and Monte Carlo simulations. We also address the impact of the distance, the transmit power, and the data rate for the proposed THz transceivers based on the link budget analysis, and confirm the accuracy of the derived BER expression.

A high‐power terahertz solid‐state amplifier fabricated using 0.25 μm InP heterojunction bipolar transistor (HBT) technology is reported. This amplifier utilies a novel defective‐ground four‐way balun to combine differential amplifier chains for a total output device periphery of 40 μm. A significant amount of power of ∼10 mW is obtained at 305 GHz with better than 20 dB small‐signal gain.

Performances of high-speed switches operating as terahertz on–off-keying (OOK) modulators are reported. Two types of switches, a passive shunt switch and an amplifier switch, are fabricated using 0.25- $\mu \text{m}$ InP double heterojuction bipolar transistor (DHBT) technology. Small-signal tests show that the amplifier switch possesses superior on–off ratio, but the passive switch has broader bandwidth and smaller group delay ripples. A modulator test setup is built with 20-dB path loss between the transmitter and the receiver. The results indicate that carrier power levels of 14 dBm for the shunt switch and 8 dBm for the amplifier switch are required for 20-Gb/s OOK modulation with bit error rate (BER) of 10 ⁻² at 290 GHz.

A new and effective millimeter-wave waveguide packaging technique suitable for 1-D spatial power-combining applications is presented. The transition structure using narrow corporate channels preserves the uniform field distribution when expanding the E-plane width of a standard waveguide to several wavelengths. A Q-band test module, containing back-to-back transitions for an increased width from 2.84 to 52 mm, shows an average insertion loss of 0.34 dB in the 40-50-GHz range. The radiation patterns from an open-end module, cut in half from the original test module, confirm uniform field distribution across the over-mode guide aperture.

A broadband terahertz amplifier waveguide module is presented. The IC chip with a width of 390 $\mu \text{m}$ fits in the $E$ -plane of a standard WR-3.4 waveguide with 20 $\mu \text{m}$ air-gaps on either side. The input and output waveguide transitions integrated on the chip possess various design factors that include locations of the dipoles, back-short pedestal, and substrate vias carefully selected for near full-band characteristics. The measurements on a module containing a passive thru-line IC chip show only 2.7 dB of average loss across 220–300 GHz range. With an amplifier IC chip mounted inside, the module shows a peak gain of 17 dB at 288 GHz with a 3 dB bandwidth from 259 to 294 GHz.