mm-Wave High Speed Modulator Design
Maryam Tabesh and Ali Niknejad
Extremely high data-rate short-range communication systems are among the emerging applications for the 60 GHz spectrum. Digital CMOS technology is a very favorable candidate for low cost and small size applications. This project explores the potential for high data-rate, low-power 60 GHz modulators. A dual-mode fully differential combined DAC-mixer structure has been introduced to improve linearity and power consumption. The quadrature, fully-differential modulator can be used in QPSK or 64-QAM mode and has the ability to provide data rates up to 30 Gb/sec. As a part of this project, a high-speed distributed microwave-style modulator has also been investigated. As a prototype, a first version of the 60 GHz modulator has been fabricated in 90 nm CMOS technology and is being tested. A current steering DAC structure with programmable tail bias current and thermometer code has been used for matching constraints.
Figure 1: Layout of the 60 GHz modulator