A 2.68-pJ/b 135-GHz OOK Transmitter With Class-F VCO in 28-nm CMOS for High-Speed Link

This work presents a 135-GHz high-speed <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small>–<sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> keying (OOK) transmitter (TX) chip fabricated in 28-nm CMOS technology. A simplified 45-GHz Class-F voltage-controlled oscillator (VCO), with low-power consumption and implicit tripling characteristic, is proposed to generate a 135-GHz local oscillator (LO) signal. A Gilbert-cell modulator is utilized to support high-speed modulation and provide a high <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on/off</small> ratio. Cascaded inverters are utilized to reshape the baseband signal distorted by external metal interconnects. Moreover, amplifiers based on neutralized <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$g_{m}$</tex-math> </inline-formula> core are used to boost the third harmonic signal at 135 GHz and amplify the D-band modulated signal. The TX was used to establish a wireless link via on-board Vivaldi antennas. Data rates of 29 and 30 Gb/s were achieved with an energy efficiency of 4.4 and 4.25 pJ/bit, respectively, over a 2-cm over-the-air (OTA) distance. In a low-loss channel such as bonding-wire connections, a data rate of 32 Gb/s with an energy efficiency of 2.68 pJ/b was achieved. PRBS31 was used to verify that the TX chip is suitable for applications requiring long pseudorandom binary sequence (PRBS) data streams. To the best of authors’ knowledge, this work achieves the highest error-free OTA data transmission rate among D-band OOK TX chips, providing a feasible CMOS solution for sub-terahertz (sub-THz) high-speed point-to-point wireless or wireline communication.