Keysight Technologies, NTT, and NTT Innovative Devices have jointly set a new world record by achieving a 280 Gbps wireless data transmission using sub-terahertz (sub-THz) frequencies in the 300 GHz band. The demonstration, which surpassed the previous 240 Gbps milestone, leverages a novel high-power, wideband Indium Phosphide (InP)-based J-band amplifier and Keysight’s advanced Vector Component Analyzer (VCA) platform with digital predistortion (DPD) capabilities. The experiment highlights key progress in enabling ultra-high-speed communications required for next-generation 6G networks and was conducted ahead of a formal presentation at the 2025 IEEE International Microwave Symposium (IMS) in San Francisco.
The 280 Gbps transmission was achieved using a 35 GBaud 256-QAM signal at 0 dBm output power in the J-band (220–325 GHz). Signal fidelity and bandwidth were enabled by the Keysight VCA, which extends the capabilities of vector network analyzers into the sub-THz domain. This system uses narrowband receivers with repetitive acquisitions and coherent averaging, significantly improving signal-to-noise ratio (SNR) while enabling wideband signal reconstruction. The amplifier IC, developed by NTT using a proprietary InP process, integrates a wideband impedance matching network and low-loss combiner to maintain output linearity and power across the entire J-band. This breakthrough addresses longstanding technical challenges in sub-THz signal generation, including power loss, signal distortion, and calibration complexity at extremely high frequencies.
NTT Innovative Devices fabricated the amplifier IC and packaged it into a WR3.4 waveguide module optimized for on-wafer and system-level testing. Saturated output power measured at +9.1 dBm significantly improves over prior demonstrations, which topped out around –9 dBm. Keysight contributed both the VCA hardware and the DPD software engine, which pre-corrects nonlinearities introduced by the amplifier. The DPD system digitally analyzes and models amplifier-induced distortion, feeding an inverse signal back to the input to linearize the transmitted waveform. Achieving high-order QAM at sub-THz frequencies with stable amplitude and phase characteristics is a critical milestone for demonstrating future 6G systems capable of Terabit-class throughput.
Beyond wireless communications, the implications of this work extend to high-resolution radar and sensing systems. Sub-THz frequencies offer extremely wide contiguous bandwidths—tens of GHz per channel—ideal for high data rate and ultra-low latency applications. However, deploying systems in this range requires robust component characterization, including S-parameters, gain compression, noise figure, intermodulation, IQ imbalance, and error vector magnitude (EVM). The Keysight 6G VCA offers full vector calibration to the device under test (DUT) reference plane, compensating for fixture loss and mismatches—an essential step for accurate component verification at these frequencies.
The research team’s next steps include transitioning from feedback-based DPD to feedforward distortion models to simplify deployment in real-time systems. NTT Innovative Devices has already begun commercializing the J-band amplifier module, targeting early adopters in academic, aerospace, and telecom industries exploring pre-6G and 6G applications. Keysight’s sub-THz measurement platform, combined with NTT’s high-efficiency amplifiers, forms a foundational toolkit for accelerating 6G component development worldwide.
- 280 Gbps achieved at 300 GHz using 35 GBaud 256-QAM, setting a new sub-THz data rate record
- InP-based J-band amplifier IC developed by NTT delivers +9.1 dBm output; WR3.4 waveguide packaging by NTT Innovative Devices
- Keysight’s Vector Component Analyzer improves SNR through repetitive signal acquisition and vector averaging
- Digital predistortion (DPD) corrects nonlinearities for high-fidelity signal generation at sub-THz frequencies
- Measurements include vector calibration, ACPR, EVM, gain compression, and I/Q imbalance across wideband spectrum
- Technology to be presented at IMS 2025; amplifier module is entering commercial production
“At NTT, we are consistently advancing the limits of carrier frequency and integration within radio systems,” said Hirokazu Takenouchi, Head of NTT Device Technology Laboratories. “These developments are pushing the boundaries of what can be achieved in wireless communication systems. The test and measurement industry is crucial in meeting the complex characterization needs of our devices. We have collaborated closely with Keysight throughout our design and verification stages. Keysight consistently provides innovative solutions in both its software and hardware platforms.”
