Design Techniques for High Frequency PAs and VCOs

Speaker: Farid Shirinfar
Affiliation: Ph.D. Candidate - UCLA

Abstract: Today’s content-centric mobile world demands Gigabit-per-second (Gbps) wireless communication systems. With sub-10GHz RF frequencies cluttered with existing wireless infrastructures such as 2.4GHz and 5GHz Wi-Fi and a multitude of LTE bands in the 1-2GHz range, the focus has shifted to microwaves and mm-waves.  The dominant non-idealities that currently limit the performance of such radios are the phase noise of voltage controlled oscillator (VCO), the maximum output power of power amplifier (PA) limited by device breakdown, and the non-linear behavior of PA.  Circuit and architecture level innovations presented in this research improve state-of-the-art performance in those areas.

A mm-wave VCO architecture with low phase noise and large tuning range is introduced. MM-wave systems rely on large channel bandwidths (e.g. 1.7GHz per channel, 7GHz total) to achieve high data rates. In the proposed architecture, the required frequency tuning range is divided amongst four narrow-band clusters of VCOs thus reducing their respective phase noise. Phase noise of each cluster is further improved by using multiple cores of VCOs. The VCO achieves a phase noise of -101.8 dBc/Hz at 1 MHz offset with an FOM of -182dB/Hz and over 12.6% frequency tuning range (50.7 GHz to 57.5 GHz).

Power amplifier (PA) performance (output power, linearity, and efficiency) is another focus of this research. Innovations in power combining techniques enable us to achieve the highest reported saturated power level of 22.6dBm in CMOS at 60GHz.  Stacking transistors as a 2nd remedy to improve the output power of PA is considered and trade-offs in gain, reliability, and output power are treated analytically and an optimal stacking strategy for mm-wave PAs is presented. A simulation-based comparison shows the superiority of the proposed optimal stacking approach for a 60GHz SiGe PA.

A wideband self-contained PA linearization technique is proposed to address the linearity issues of mm-wave PAs. The proposed Adaptive Gain and Phase Adjustment (AGPA) linearization technique compensates for both AM-AM and AM-PM distortion of the PA for large channel bandwidths of hundreds of megahertz at mm-waves. The gain and phase linearization loop consists of an envelope detector, an Analog Mapping Core (AMC), and a variable RC feedback network. The detection and adjustment loop has a low group delay and thus enables one of the largest published linearization bandwidths. AGPA improves the OP1dB of a stacked mm-wave PA by 2.8dB from 9.5dBm to 12.3dBm and reduces the IM3 products with a tone spacing of 200MHz by 3dB at 8dBm output power.  PAE at OP1dB is improved from 6.5% to 10.5% by enabling AGPA at 57GHz.

Biography: Farid Shirinfar received the B.S. and M.S. degrees in Electrical Engineering with honors from University of California, Los Angeles (UCLA) in 2010 and 2011. He is currently pursuing the Ph.D. degree in Electrical Engineering at UCLA. He worked at Sony R&D in Tokyo in 2009, where he developed MEMS-based magnetic structures. He joined Broadcom’s RFIC group in Irvine in 2010, where he has worked on the 1st generations of microwave and mm-wave radios.   He was the RFIC chip lead for the 1st generations of two microwave radios capable of 4096QAM and Gigabit-per-second (Gbps) communication. His research interests are high frequency circuits and systems, point-to-point microwave and mm-wave systems, and short range wireless power and data transmission. He is the author of several technical papers and five granted US patents.

For more information, contact Prof. Sudhakar Pamarti ()

Date(s) - Mar 21, 2016
12:00 pm - 2:00 pm

E-IV Tesla Room #53-125
420 Westwood Plaza - 5th Flr., Los Angeles CA 90095