SiGe BiCMOS active phase shifter design for W-band automotive radar applications
Öztürk, Efe (2014) SiGe BiCMOS active phase shifter design for W-band automotive radar applications. [Thesis]
In this thesis, the design and measurement results of the fabricated LNA and phase shifter chips to be utilized in W-band Automotive Radar Applications are presented. The chips are manufactured using 0.13μm and 0.25μm SiGe HBT technologies. Observing the high insertion loss of the fabricated 4-bit MEMS based digital phase shifter which is around 15.3-18.1dB, two active phase shifter designs based on different vector-modulator topologies are offered. Amongst these structures, three-way active phase shifter is composed of Wilkinson power divider/combiner which separates the input signal into three vectors, additional phase lines dividing the 360o phase spectrum into three regions by adding 120o consecutive phase to each vector and LNAs to rotate the main antenna beam in these regions by the weighted sum of vectors. According to measurement results of the 100mW consuming 1.65mm2-sized chip, continuous 360o phase shifting is clearly achieved with 11dB peak gain at 77GHz, no insertion loss up to 90GHz and return losses better than 10dB for all the phase states. On the other hand, a two way I/Q type MEMS based active phase shifter is also in fabrication. The continuous phase shifting is realized in I- and Q-separated two amplification stages, using weighted sum method, to rotate in a single 90o quadrant and then employs 1-bit (0o-180o) MEMS phase shifter blocks to cover 360o in 4 states by shifting this quadrant about 90o. The simulation results of 3.74mm2 chip point out above-15dB input/output return loss and a variable 3-7.5dB gain at 77GHz with the tuned LNA voltages. Using these active phase shifters, phased array radars could provide higher gain in a smaller die area with reduced cost due to the used SiGe technology and automotive radars with high perfromances could be achieved.
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