DSP Wireless Systems Engineer

DSP Wireless Systems Engineer Sunnyvale, California, United States Hardware At Apple, we work every single day to craft products that enrich people’s lives. Do you love working on challenges that no one has solved yet? Do you like changing the game? We have an opportunity for a forward-thinking and unusually hardworking Wireless System Engineer. As a member of our dynamic group, you will have the rare and extraordinary opportunity to craft upcoming products that will delight and encourage millions of Apple’s customers every single day. For wireless systems, power amplifiers (PA) in the transmitter are the main source of power consumption. To improve efficiency, PA must be designed beyond the classic class-AB, together with enhancement using envelope tracing, or envelope elimination and restoration (EER, or polar transmitter). Those designs come with impairments or nonlinear distortion that need to be cleaned up using digital signal processing (DSP) techniques. RF/analog architectures with the help of DSP, their optimizations and calibrations are the critical technique to achieve such high performing systems. In this technical role, you will be at the center of a silicon design group responsible for using digital algorithms or methods to improve PA efficiency, reducing power consumption, but with acceptable linearity for high data rate applications. You will mainly work on architecting various calibration and correction methods for implementation in hardware/firmware and validation of overall performance enhancement through lab measurement. You will interact with RF/analog designers, software or firmware engineers, digital designers, product engineers and architects to define and specify parts in the wireless systems. You will also get to work with digital designers and firmware designers to realize these methods with power and area efficient digital implementations with high efficiency software implementations, and possibly with hardware acceleration. And to bring up, test, characterize, and optimize real silicon in lab to the production qualities. Description In this role, core responsibilities include, but are not limited to, the following: Design and simulate state-of-the-art wireless transmitter for very high data rate applications. Investigate innovative PA architectures, calibration algorithms, processing structures for performance enhancement. Architect HW/FW/SW partitioning of various calibrations for area and time efficiency. Implement system models of the analog front-end design, impairments and come up with right controls and calibrations in C and MATLAB for optimal system performances. Work with digital designers to realize these methods with power and area efficient digital implementations. Work with firmware designers to realize these methods with high efficiency software implementation, and possibly hardware acceleration. Bring up, test and characterize real silicon with relevant implementation in lab. Minimum Qualifications BS and a minimum of 10 years relevant industry experience. Experience in designing relevant signal processing for wireless communications systems. Understand the methods to estimate various RF impairments via direct equipment measurement or self-testing via loopback. Experience with MATLAB or Python and/or C/C++ for algorithm development, modeling, and simulation. Hands-on experience on lab testing & characterization (such as spectrum analyzer, signal generator, signal analyzer, power meter, etc.). Some understanding of RF and analog components/modules composed of wireless communication systems, the possible impairments from those components, their impact to OFDM signals, and the corresponding calibration and impairment reduction methods/algorithms. Key Qualifications Preferred Qualifications MSEE/PhD with relevant experience. Proven track record of optimization algorithm, and its applications to RF calibration. Previous experiences on digital predistortion, crest-factor reduction, nonlinear crosstalk/interference cancellation, and real-chip bring-up in lab. Understand communication theory & signal processing related algorithms design (such as timing recovery, signal estimation and detection, automatic gain control, channel estimation, equalization, coding theory, etc.). Knowledge in existing wireless communication protocols: 5G-NR/LTE/WCDMA/GSM, 802.11 WiFi, and/or Bluetooth/BLE. Course works and experience in circuit design.

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