PhD Position - mm-Wave mixing ADC for automotive digital (FMCW) radar receivers

Benefits

• ing from re-use for the back-end stage design.
• Background Frequency‑modulated continuous‑wave (FMCW) radar has become the dominant sensing modality for automotive radar applications due to its robustness, high range resolution, and compatibility with compact CMOS implementations.
• In FMCW radar systems, distance and velocity information are extracted from the frequency difference between the transmitted chirp and the received echo, which places stringent requirements on receiver linearity, noise performance, and bandwidth.
• As radar systems evolve toward higher resolution and multi‑antenna (MIMO) configurations, the receiver front‑end must support increasingly wide instantaneous bandwidths while maintaining low power consumption and high dynamic range.
• Modern FMCW radar receivers typically operate in the 76–81 GHz band and rely on down‑conversion of the received millimeter‑wave (mmW) signal to baseband.
• This function is performed by mmW mixers, which translate the high‑frequency input signal using a local oscillator (LO) derived from the same chirp generator as the transmitter.
• Mixer performance is critical, as it directly impacts receiver noise figure, linearity, and spurious response.
• Both voltage‑mode and current‑mode mixer topologies are commonly used at mmW frequencies, each presenting trade‑offs in terms of conversion gain, isolation, and compatibility with subsequent baseband circuitry.
• Implementing these mixers in advanced CMOS technologies enables high levels of integration but also exacerbates challenges related to device noise, parasitics, and LO leakage.
• A key architectural trend in FMCW radar receivers is the push towards earlier digitizing, placing the analog‑to‑digital converter (ADC) closer to the antenna interface.
• Early digitization reduces the complexity of analog baseband processing, improves calibration capabilities, and facilitates digital beamforming in MIMO systems.
• However, this shift places stringent requirements on the ADC, which must handle wide signal bandwidths, large dynamic range, and strong interferers while operating at low supply voltages.
• Continuous‑time sigma‑delta (CT ΣΔ) ADCs are particularly attractive in this context due to their inherent anti‑alias filtering, high linearity, and excellent noise‑shaping properties.
• Integrating a mmW mixer directly into a CT ΣΔ ADC represents a promising but challenging approach for next‑generation FMCW radar receivers.
• The mixer‑ADC interface must simultaneously satisfy conflicting requirements on noise, linearity, stability, and clocking, particularly at carrier frequencies around 76-81 GHz.
• Careful architectural choices and circuit‑level innovation are therefore required to realize a robust, low‑power solution capable of direct digitization and demodulation of FMCW radar signals.
• Key research challenges include the interaction between mmWave mixing and continuous‑time ΣΔ feedback loops, LO phase‑noise, and stringent linearity constraints under FMCW chirp excitation.
• The project will explore architectural and circuit‑level innovations to address these challenges.
• Requirements for this role Master’s degree in electrical engineering or related field Strong background in mmW and analog/mixed-signal circuit design Background in data converters Experience in Cadence and Matlab Project Plan Phase 1: System architecture and behavioral modeling, define system specifications and performance targets.
• Phase 2: Circuit design and simulation.
• Phase 3: Layout, fabrication, and testing of prototype design.
• Phase 4: Publication and benchmarking.
• This 4 years PhD project is a cooperation between Delft University of Technology and NXP Semiconductors.
• Interested in joining our team? Submit your CV and personal background and let us talk about it! Supervisors: Kofi Makinwa (Delft University) Lucien Breems (NXP Semiconductors, Delft University) Muhammed Bolatkale (NXP Semiconductors, Delft University) More information about NXP in the Netherlands... #LI-f5d0