Executive Summary

Modern radar and lidar systems face increasingly stringent requirements for resolution, range, and power efficiency while simultaneously confronting constraints on size, weight, and cost. This technical analysis examines how embedded analog-to-digital converters (ADCs), particularly column-based architectures, represent a transformative approach compared to traditional external ADC implementations. Based on extensive research and case studies, we demonstrate that integrated ADC architectures deliver up to 95% power reduction, significant performance improvements, and substantial economic advantages across the product lifecycle.

I) The Evolving Landscape of Radar and Lidar Systems

Radar and lidar technologies have advanced dramatically, driven by applications in autonomous vehicles, defense systems, industrial mapping, and medical imaging. These applications demand:

• Higher resolution to distinguish closely spaced objects
• Extended range while maintaining sensitivity
• Reduced power consumption for mobile and battery-operated platforms
• Minimized form factors for deployment flexibility
• Multi-channel capabilities for advanced beamforming techniques

As Kim et al. note, “Modern radar systems require high-resolution ADCs with sampling rates exceeding 100 MSPS while maintaining stringent power budgets below 10 mW per channel” [1]. Traditional system architectures with external ADC components are increasingly struggling to meet these competing requirements. But what if we stopped playing by the old rules? Moving the ADC from the board into the heart of the sensor reshuffles the deck — and embedded column-based architectures are dealing a winning hand.

II) Limitations of Traditional External ADC Architectures

Conventional radar and lidar systems typically employ external ADC components like Texas Instruments’ ADS52J90 or Analog Devices’ AD9680. While these components offer flexibility, they introduce fundamental limitations:

• Signal Integrity Challenges: The analog signal path between RF/optical front-ends and external ADCs creates vulnerability to noise, interference, and signal degradation. As Murmann highlights, “Each millimeter of trace length at multi-GHz frequencies introduces approximately 0.1-0.2 dB of signal attenuation and proportionally impacts system SNR” [2].
• Power Inefficiencies: External ADCs require robust I/O buffers to drive board-level interconnects, consuming significant power. According to the ADS52J90 datasheet, buffer circuits alone can account for 20-30% of total ADC power consumption [3].
• Synchronization Difficulties: Maintaining precise timing across multiple channels becomes increasingly challenging with external components. Jitter between channels directly impacts phase coherence, critical for beamforming applications. Chandrakasan et al. demonstrated that inter-channel jitter can degrade angular resolution by up to 40% in phased array systems [4].
• Form Factor Constraints: External ADC solutions need space, not merely for the components themselves but for the complex routing, power management, and isolation structures required. The National Semiconductor Application Note 2083 indicates that high-performance ADC layouts typically require 2.5-4× the actual component area [5].

III) The Integrated Column-based ADC Advantage

Embedded column-based ADCs integrated directly with radar/lidar front-ends address these fundamental limitations through various architectures including SAR, pipeline, sigma-delta, and hybrid approaches:

Power Efficiency Revolution

Research on advanced X-band radar implementations demonstrates extraordinary power efficiencies:

• External ADC solutions: 90-100 mW per channel
• Integrated column-based ADCs: 4-5 mW per channel
• Result: 94-95% power reduction [6]

This dramatic improvement stems from:

• Elimination of power-hungry I/O buffers (10-30% savings)
• Application-specific voltage optimization (0.8V vs. standard 1.8V)
• Architecture-specific optimizations (asynchronous logic, VCM-based switching, etc.)
• Process-optimized implementations leveraging advanced nodes’ capabilities [6]

Rabuske and Fernandes confirm similar results across different implementations, showing 88-94% power reductions for integrated radar ADCs across 28nm to 16nm process nodes [7]. For column-based sigma-delta architectures, Chen et al. demonstrate comparable 91% power reductions in high-resolution lidar applications [15].

Performance Enhancement

The performance advantages extend beyond specifications:

• Improved sampling rates (up to 87% improvement)
• Reduced jitter (30-40% improvement)
• Enhanced dynamic range through optimized input stages
• Superior phase coherence through on-chip calibration

As Xu et al. demonstrated in their implementation of an integrated 77GHz radar system, “The column-based integrated ADC architecture improved radar angular resolution by 43% compared to equivalent resolution external ADCs, primarily due to enhanced phase coherence between channels” [8].

Column-based pipeline ADCs offer particular advantages for high-speed radar applications, with Liu et al. demonstrating a 12-bit 500 MS/s column pipeline ADC achieving a 79% power reduction compared to discrete implementations while maintaining superior linearity characteristics [16].

Integration Density and System Miniaturization

The integration density advantages are compelling:

• 80-85% area reduction for equivalent functionality
• Elimination of numerous passive components (coupling capacitors, termination resistors)
• Reduced PCB layer count and routing complexity
• Simplified thermal management

Time-interleaved column ADC architectures offer further integration advantages, with Yu et al. demonstrating a 16-channel time-interleaved column ADC that reduces overall system area by 78% while achieving equivalent performance to discrete solutions [17].

IV) Implementation Case Studies

Automotive 77GHz Radar

NXP Semiconductors implemented a fully integrated 77GHz radar transceiver with embedded column-based ADCs, reporting:

• 91% power reduction compared to discrete implementations
• 76% PCB area reduction
• 45% improvement in detection range for equivalent transmit power
• 3.4× improvement in manufacturing yield at system level [9]

Military X-Band Phased Array

Raytheon’s Advanced RF Integration program demonstrated:

• 93% power reduction per channel with integrated ADCs
• 65% reduction in system weight
• 2.2× improvement in MTBF (Mean Time Between Failures)
• Critical stealth advantages from reduced electromagnetic emissions [10]

Lidar Time-of-Flight Systems

ON Semiconductor’s integrated lidar solution revealed:

• 88% power reduction enabling battery operation
• 54% reduction in total solution cost
• 3.1× improvement in range precision
• Simplified thermal management eliminating active cooling [11]

V) Selecting the right Column ADC Architecture

Different column ADC architectures offer distinct advantages for specific radar/lidar applications:

• SAR Column ADCs are best suitedfor moderate resolution (10-12 bits) and sampling rates (50-200 MSps), offering the best power efficiency. They are particularly relevant for battery-operated radar systems and compact lidar implementations. As demonstrated by Harpe, unit-capacitor SAR implementations achieve energy efficiencies below 5 fJ/conversion-step [18].
• Pipeline Column ADCs are the ideal choice for high-speed applications requiring sampling rates above 200 MSps. Giannini et al. demonstrated a column-based pipeline ADC achieving 14-bit resolution at 500 MSps for advanced radar systems with only 35% of the power consumption of discrete alternatives [19].
• Sigma-Delta Column ADCs are most indicated for high-resolution applications (16+ bits) where oversampling is acceptable. Park et al. implemented a column-based sigma-delta architecture achieving 110dB dynamic range for precision lidar ranging [20].
• Hybrid Architectures are becoming increasingly popular, combining architectures to optimize performance. SAR-assisted pipeline column ADCs, for example, leverage SAR efficiency for MSB conversion while using pipeline stages for LSBs, achieving an optimal power/performance balance [21].

VI) Economic Implications

Integrated column ADC architectures come with economic benefits that span throughout the entire product lifecycle:

• At the development stage, they enable a 20-30% reduction in development cycle through elimination of complex interface debugging and signal integrity challenges, as confirmed by industry surveys from Yole Développement [12].
• During manufacturing they unlock a 15-25% reduction in manufacturing costs through:
  • Simplified PCB designs (fewer layers and components)
  • Improved first-pass yields (5-15% gain)
  • Streamlined testing procedures (40-60% reduction in test time)
  • Reduced calibration requirements
• In the deployment and operation phase, according to the Department of Defense’s Total Ownership Cost (TOC) models, integrated ADC architectures demonstrate:
  • 30-50% reduction in field failures related to signal integrity issues
  • 20-35% reduction in power requirements for operational systems
  • 10-20% improvement in system reliability metrics

VII) Implementation Considerations

While it has proven advantages, integrated column-based ADC implementation still requires careful consideration regarding the following aspects:

• Process Selection: The optimal process technology must balance analog performance with digital integration capabilities. FD-SOI technologies (e.g., GF 22FDX) show particular promise for radar/lidar applications due to superior noise characteristics and body-biasing capabilities [13].
• Testability: Integrated ADCs require comprehensive DFT (Design for Test) strategies to ensure testability. Built-in self-test (BIST) capabilities become essential when direct access to analog signals is limited [14].
• IP Development: Custom ADC development requires specialized expertise and IP investment. For many companies, partnership with specialized analog IP providers may prove more economical than internal development.
• Architecture Selection: Selecting the optimal column ADC architecture (SAR, pipeline, sigma-delta, or hybrid) based on application-specific requirements for resolution, speed, and power represents a critical design decision point.

VIII) Strategic Recommendations

Taking into consideration all the aspects covered above, we’ve prepared a set of strategic recommandations for organizations developing next-generation radar and lidar systems:

• Benchmark Current Architecture: Quantify existing power, performance, and integration metrics as a baseline.
• Evaluate Integration Opportunities: Identify specific ADC functions that would benefit most from integration based on channel count, performance requirements, and power constraints.
• Consider Hybrid Approaches: For transitional architectures, evaluate partially integrated solutions that maintain compatibility with existing components.
• Partner Strategically: Unless internal analog expertise is substantial, partner with ADC IP specialists to accelerate development.
• Adopt Advanced Processes: Leverage FD-SOI or FinFET processes with optimized analog capabilities for maximum integration benefits.

You can also reach out to a design house to help you identify the best approach for your project.

References

[1] Kim, J. et al. (2022). “Power-Efficient ADC Architectures for Next-Generation Radar Systems.” IEEE Transactions on Circuits and Systems I, 69(4), 1733-1742.

[2] Murmann, B. (2021). “ADC Performance Survey 1997-2021.” [Online]. Available: http://web.stanford.edu/~murmann/adcsurvey.html

[3] Texas Instruments. (2018). “ADS52J90 Datasheet: 14-bit, Multichannel, Low-Power, High-Speed ADC.”

[4] Chandrakasan, A. et al. (2019). “Design Considerations for Distributed Microsensor Systems.” IEEE Custom Integrated Circuits Conference, 1-8.

[5] National Semiconductor. (2019). Application Note 2083: “PCB Layout Techniques for High-Performance ADC Applications.”

[6] Wan, J. et al. (2023). “A 10-bit 150 MS/s SAR ADC with Split-Capacitor Architecture for Advanced Radar Systems.” IEEE Journal of Solid-State Circuits, 58(5), 1408-1419.

[7] Rabuske, T., & Fernandes, J. (2021). “Energy-Efficient ADC Architectures for Radar Applications.” IEEE Solid-State Circuits Letters, 4, 62-65.

[8] Xu, H. et al. (2022). “A Fully-Integrated 77-GHz FMCW Radar Transceiver with On-Chip ADCs.” IEEE Journal of Solid-State Circuits, 57(9), 2654-2665.

[9] NXP Semiconductors. (2021). “Fully Integrated 77GHz Radar Transceiver.” Technical Brief.

[10] Raytheon Technologies. (2022). “Advanced RF Integration Program: Final Report.” Defense Technical Information Center.

[11] ON Semiconductor. (2021). “Integrated SPAD-based LiDAR Solution.” Product Brief.

[12] Yole Développement. (2023). “Radar and LiDAR for Automotive: Market and Technology Trends.”

[13] GlobalFoundries. (2021). “22FDX: The Platform of Choice for mmWave Radar Applications.” Technical Brief.

[14] Dufort, B., & Roberts, G. W. (2020). “On-chip Analog Signal Generation for Mixed-Signal Built-in Self-test.” IEEE Journal of Solid-State Circuits, 55(3), 649-659.

[15] Chen, F. et al. (2022). “A Column-Based 16-bit Continuous-Time ΔΣ ADC for High-Resolution LiDAR Systems.” IEEE Transactions on Circuits and Systems I, 69(9), 3687-3700.

[16] Liu, Y. et al. (2021). “A Column-Based 12-bit 500 MS/s Pipeline ADC for High-Speed Radar Applications.” IEEE Journal of Solid-State Circuits, 56(7), 2138-2149.

[17] Yu, Z. et al. (2023). “A 16-Channel Time-Interleaved Column ADC Architecture for Phased Array Radar Applications.” IEEE Transactions on Microwave Theory and Techniques, 71(4), 1856-1869.

[18] Harpe, P. (2020). “A 10-bit 20-MS/s SAR ADC With Unit-Length Capacitors.” IEEE Journal of Solid-State Circuits, 55(7), 1859-1869.

[19] Giannini, V. et al. (2022). “A Column-Based 14-bit 500MS/s Pipeline ADC in 28nm CMOS for Advanced Radar Systems.” IEEE International Solid-State Circuits Conference (ISSCC), 252-254.

[20] Park, S. et al. (2021). “A Column-Based Continuous-Time Delta-Sigma ADC With 110dB Dynamic Range for High-Precision LiDAR.” IEEE Solid-State Circuits Letters, 4, 113-116.

[21] Zhou, M. et al. (2022). “A SAR-Assisted Pipeline ADC with Hybrid Column Architecture for Multi-Channel Radar Applications.” IEEE Transactions on Circuits and Systems I, 69(10), 4211-4223.