Mm-wave frequencies (30 GHz - 300 GHz) offer opportunities for many wireless applications involving two basic human activities: communication and sensing. Examples are high-datarate wireless communications (e.g. 60 GHz data links with datarates higher than 1 Gbit/s), automotive radars (e.g. 79 GHz car radars) and image sensors (e.g. 94 GHz). Modern CMOS technologies enable the realization of mm-wave transceivers thanks to the speed increase and the (relative) low cost. One of the main challenges in such transceivers is the frequency synthesis, which is the synthesis of the local oscillator's signal. The local oscillator of a transceiver is like the heart of a human being: it gives the rhythm to the whole system. Typically, phase-locked loops are used for this task. Mm-wave phase-locked loops require mm-wave frequency dividers. Traditionally, static logic latches are used as frequency dividers, but they require large power consumption at mm-wave frequency. For this reason, alternative approaches are needed, which can handle the high-frequency operation in CMOS technology. Alternative approaches can use injection-locking techniques, where an oscillatory system is synchronized to a multiple or submultiple of the fundamental frequency of a reference signal. Two possible utilizations are inductorless mm-wave injection-locked frequency dividers and mm-wave subharmonically injection-locked oscillators. Inductorless mm-wave injection-locked frequency dividers can work at high frequency, consume a small amount of power, can be tuned over a wide frequency range and are compact. As drawback, they are sensitive to supply disturbances. This Ph.D. devises an inductorless injection-locked 60-15 GHz injection-locked frequency divider, with a low supply sensitivity, in 40 nm CMOS. Mm-wave subharmonically injection-locked oscillators are synchronized with a lower-frequency phase-locked loop. Apart from the absence of mm-wave frequency dividers, another advantage is that the phase noise of the mm-wave oscillator is lowered by the injected lower-frequency signal. However, such a system usually suffers from a narrow locking range and requires lock detection. This Ph.D. devises a novel approach where the use of coupled-LC tanks allows for a large locking range, calibration is facilitated by envelope detection and lock is detected with a simple harmonic lock-in amplifier, in 40 nm CMOS.
|Place of Publication||Brussels|
|Publication status||Published - 2015|