Performance Evaluation of a 220–260 GHz LO Tunable BPSK/QPSK Wireless Link in SiGe HBT Technology

A QPSK 110-Gb/s Polarization-Diversity MIMO Wireless Link With a 220–255 GHz Tunable LO in a SiGe HBT Technology

“…This minimum value of around 18% holds for the lower wireless distance, indicating that the SNR does not limit the link in its current state. By comparison with our previous wireless experiments [15], [16], [36] that operated the TX/RX BB ports fully differentially and reported an EVM as low as 7% for the same baud rates, the main source of EVM deterioration was found to be an imbalanced single-ended drive of the high-speed ports through the wire-bonded interconnects, as previously mentioned in Section III-A. A minimum EVM of 18% in each single-polarization path currently prevents the MIMO operation with higher order modulation formats, such as 16-QAM, even though the measured RHCP-to-LHCP isolation may potentially provide it.…”

“…This benefit, however, comes at the cost of some other challenges, which may considerably influence the performance of a single transmission channel. One of the most, if not the most, important is the necessity of IQ operation at RF frequency [15], [16], which is removed with an IF architecture. It leads to potentially substantial leakage between I and Q channels that may dominate other impairments and limit the achievable data rates despite a sufficient arbitrary white Gaussian noise-defined (AWGN) signal-to-noise ratio (SNR).…”

“…The multiplication factor was chosen as a compromise between the limited RF performance of the wire-bond interconnection and the circuit implementation complexity. Assuming ideal noise scaling of 20 log 10 (16) = 24.1 dB by upconversion to 240 GHz, an rms phase error of around 5 • is already anticipated for a 15-GHz range BB BW [16], [39], which sets a practical upper boundary on the modulation format around 64-QAM.…”

“…This leads to This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see https://creativecommons.org/licenses/by/4.0/ not only poor power efficiency and tight link budget but also results in a very limited scaling of the BW with the carrier frequency increase and a considerable asymmetry between lower and upper sidebands (LSB and USB) [15], [16]. Such deficiencies become particularly pronounced for CMOS technologies [17], [18], where fundamentally operated architectures are not readily available, and massive power combining needs to be applied for any reasonable transmitted power levels [19]- [24].…”

A Broadband 300 GHz Power Amplifier in a 130 nm SiGe BiCMOS Technology for Communication Applications

“…F UTURE wireless links, operating in the IEEE 802.15.3d-2017 band around 300 GHz [1], require several tens of gigahertz of absolute radio frequency (RF) bandwidths to support 100+ Gb/s networks [2], [3]. Limited link budget, high receiver noise figure, and other impairments resulting from the circuit operation at the speed-related technology boundary limit systems to low-order modulation schemes with low spectral efficiency [4]- [7]. In addition, gain flatness and group delay stability have growing importance next to output power, power efficiency, and linearity for ultra broadband communication, as they are directly related to the symmetry between the upper and lower sidebands [8].…”