The capability of downscaled CMOS to handle signals at millimeter-wave frequencies (30-300GHz) opens a wide variety of applications that can be miniaturized, by which they can be brought to the consumers at an affordable cost. For example, the ISM band between 57GHz and 66GHz is being used for wireless communication at data rates well above 1 Gbit/s, according to the IEEE 802.11ad standard, and various CMOS and BiCMOS ICs are commercially available for this standard. Apart from communication applications in the mm-wave range, radar applications have also gained in attention in the last few years. For example, in the automotive world, CMOS and BiCMOS radar chips are commercially available for ranges beyond 100 meter.
Imec has developed over the last years several chips for automotive radar, operating around 79GHz and it is now extending this field to indoor applications. Radar technology, especially when it can be miniaturized, can be used indoor for a wide variety of indoor applications. Industrial applications in the field of material analysis, quality control of products are a few examples. Another field of applications, more oriented to persons is detection of the presence of people in a room, detection of breathing and heartbeat, gesture recognition, .... In these cases, the range, the speed and the orientation of targets with respect to the sensor are necessary parameters.
For any waveform that is used in radar, the resolution of the range is equal to c/BW/2 where c is the speed of light and BW is the bandwidth that is used by the transmitted waveform. The speed of the targets can be detected from the Doppler shift of the received frequency. The orientation can be determined for example by using multiple antennas that enable to steer the antenna pattern.
Recently, the spectrum between 64GHz and 71GHz has been opened for unlicensed use. Combined with the 57-66GHz frequency band mentioned above, this results in a contiguous band of 14GHz. The goal of this PhD. is to make a CMOS-based radar sensor that uses this 14GHz band, yielding a range resolution around 1cm. The focus of this PhD. is limited to the design of the analog and RF circuitry of the transmit and receive part. The antennas will be designed by someone else, in collaboration with this PhD. work. The power consumption needs to be as low as possible, lower than 100mW, to allow for an integration of this transceiver into mobile terminals. Moreover, if power consumption is low enough, then the sensor can be powered with energy harvesting. This would enable the development of low-cost, autonomous, batteryless sensors that can be deployed at a large scale. This strong pressure on the power consumption necessitates a preliminary architectural study and an optimization of the transmit/receive link budget. Hereby, the short range can be exploited by relaxing the transmit power, the receiver sensitivity and the phase noise of the local oscillator. Further, the efficiency of the transmitter will be optimized to values that are higher than the typical values of the widely used class A stages, which are often below 10%. Finally, the large relative bandwidth is a challenge for the tuning range of the VCO as well as for the impedance matching networks in the signal paths.
As a PhD student, you will design the transceiver architecture and its composing circuits amid a group of analog IC designers, both payroll people and PhD. students, surrounded by system-level designers and digital design experts.
Required background: Electrical Engineering
Type of work: 10% literature, 90% IC design including measurements
Supervisor: Piet Wambacq
When you apply for this PhD project, mention the following reference code in the imec application form: ref. SE 1704-26.