Systematic high-level design of a fifth order Continuous-Time CRFF Delta Sigma ADC
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2021-02-21 |
| Authors | M. Germain, F. Rarbi, O. Rossetto |
| Institutions | Université Grenoble Alpes |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: High-Level Design of a CT Delta Sigma ADC for Diamond Detectors
Section titled âTechnical Documentation & Analysis: High-Level Design of a CT Delta Sigma ADC for Diamond DetectorsâThis document analyzes the requirements set forth in the paper âSystematic high-level design of a fifth order Continuous-Time CRFF Delta Sigma ADC,â focusing specifically on the material science implications for the underlying diamond detector technology.
Executive Summary
Section titled âExecutive SummaryâThis research details the systematic design of a high-performance Continuous-Time Delta Sigma ADC (CT ÎÎŁ ADC) intended for next-generation particle detectors based on diamond. The core value proposition and material requirements are summarized below:
- Application Focus: The ADC is designed for energy measurement systems used in particle identification, specifically targeting detectors built upon diamond substrates.
- Performance Achieved: The proposed 5th order Cascaded Resonators Feedforward (CRFF) architecture achieved a simulated Effective Number of Bits (ENOB) of 11.9 bits (73.5 dB SQNR) at a 40 MHz bandwidth.
- Critical Challenge: The design exhibits extreme sensitivity to component dispersion (process variation of R and C values in Opamp-RC integrators), requiring tolerances as tight as ±10% process variation (Îp) and ±0.5% mismatch (ÎŽm) for critical loop coefficients.
- Material Requirement: The successful implementation of the overall system hinges on the use of high-purity, stable diamond material, which serves as the primary sensing element for particle detection.
- 6CCVD Value Proposition: 6CCVD provides the necessary high-quality, ultra-low defect density Single Crystal Diamond (SCD) substrates required to ensure the stability and performance demanded by these high-speed, low-noise front-end electronics.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the synthesis and simulation results of the proposed CT ÎÎŁ ADC modulator:
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Target Resolution | 10 | bits | Required ENOB |
| Simulated ENOB | 11.9 | bits | Achieved performance |
| Signal Bandwidth (BW) | 40 | MHz | Target specification |
| Sampling Frequency (Fs) | 640 | MHz | OSR = 8 |
| Theoretical SQNR | 80 | dB | Calculated maximum |
| Simulated SQNR (Ideal) | 73.5 | dB | Achieved performance |
| Loop Filter Order (L) | 5 | - | CRFF Architecture |
| Modulator ADC N | 3 | bits | Quantizer resolution |
| Integrator DC Gain | 40 | dB | Required for Opamp-RC integrators |
| Integrator Saturation Voltage | ±450 | mV | Maximum output swing limit |
| Critical Process Variation (Îp) | < 10 | % | Required tolerance for R/C stability |
| Critical Mismatch Error (ÎŽm) | < 0.5 | % | Required tolerance for R/C stability |
Key Methodologies
Section titled âKey MethodologiesâThe systematic high-level design utilized a model-based approach combining graphical behavioral simulation with custom MATLAB scripts to optimize the CT ÎÎŁ modulator for diamond detector applications.
- Specification Definition: Target specifications (10-bit ENOB, 40 MHz BW) were defined, leading to the selection of a low OverSampling Ratio (OSR) of 8 and a high sampling frequency (640 MHz).
- Architecture Selection: The Cascaded Resonators Feedforward (CRFF) architecture was chosen due to its wide bandwidth, low OSR capability, and ability to limit noise and distortion through large bias currents in the first stage.
- Synthesis and Modeling: The modulator was synthesized using Schreierâs Toolbox integrated into a SIMULINK graphical behavioral model.
- Systematic Dispersion Analysis: Custom MATLAB scripts were integrated to perform parametric Monte Carlo simulations (10,000 iterations) to analyze the effect of component dispersion (process variation Îp and mismatch ÎŽm) on the final SQNR.
- Critical Parameter Identification: Simulations identified the loop coefficients (a1, a2, b1, c1) as the most critical parameters, requiring extremely tight tolerance control (Îp < 10%, ÎŽm < 0.5%) to maintain desired specifications.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThe successful deployment of this high-speed ADC relies on the performance and stability of the underlying diamond detector. 6CCVD provides the specialized MPCVD diamond materials and engineering services necessary to meet the stringent requirements of next-generation particle physics instrumentation.
Applicable Materials
Section titled âApplicable MaterialsâThe applicationâenergy measurement and particle identificationâdemands materials with exceptional charge transport properties, high radiation hardness, and low intrinsic noise.
| 6CCVD Material | Recommended Grade | Rationale for Application |
|---|---|---|
| Single Crystal Diamond (SCD) | Optical/Detector Grade | Essential for high-performance particle detection. Offers the highest purity, lowest defect density, and superior charge collection efficiency (CCE) required for stable, low-noise signal generation feeding the CT ÎÎŁ ADC. |
| Boron-Doped Diamond (BDD) | Heavy Doping (p-type) | Used for creating highly conductive electrodes directly on the diamond surface, eliminating the need for complex metal contacts in certain detector designs, thereby reducing interface noise and improving long-term stability. |
| Polycrystalline Diamond (PCD) | High Purity (HPHT/MPCVD) | Suitable for large-area support substrates (up to 125mm) or applications where the diamond acts as a stable, high-thermal-conductivity heat spreader for the integrated CMOS electronics. |
Customization Potential
Section titled âCustomization PotentialâThe integration of the high-speed Opamp-RC integrators and the diamond sensor requires precise material engineering and interface control. 6CCVD offers comprehensive customization services to facilitate this integration:
- Custom Dimensions: We supply SCD plates up to 10mm thick and PCD wafers up to 125mm in diameter, allowing for large-area detector arrays or integrated sensor/electronics platforms.
- Precision Polishing: SCD substrates can be polished to an ultra-smooth surface finish (Ra < 1nm), critical for minimizing surface defects and ensuring optimal deposition of subsequent metalization layers or CMOS components.
- Advanced Metalization: The integration of the front-end electronics requires robust, low-resistance contacts. 6CCVD offers in-house deposition of critical metal stacks, including:
- Ti/Pt/Au: Standard stack for robust, low-resistance ohmic contacts.
- W/Cu: High-thermal-conductivity stacks for heat dissipation in high-power applications.
- Thickness Control: SCD and PCD layers can be grown and processed to precise thicknesses ranging from 0.1”m to 500”m, enabling optimization of detector capacitance and charge collection depth.
Engineering Support
Section titled âEngineering SupportâThe paper highlights that the primary challenge is minimizing component dispersion to maintain high SQNR. While this relates to CMOS fabrication, the stability of the diamond detector itself is the foundation.
- Material Selection Consultation: 6CCVDâs in-house PhD team specializes in diamond physics and detector design. We assist engineers in selecting the optimal diamond grade (e.g., specific nitrogen concentration, defect density) to minimize intrinsic noise and maximize signal fidelity for Particle Identification and Energy Measurement projects.
- Interface Optimization: We provide technical guidance on surface preparation and metalization schemes to ensure stable, low-noise interfaces between the diamond sensor and the high-speed analog front-end (AFE) electronics described in this research.
- Global Logistics: We ensure reliable, fast global shipping (DDU default, DDP available) for time-critical research and development projects.
Call to Action
Section titled âCall to ActionâFor custom specifications or material consultation regarding high-performance diamond detectors and integrated electronics, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
In this paper we present the development of a Systematic high level design model based on MATLAB scripts. It is integrated into a graphical behavioral model toolbox for the synthesis and simulation of a Continuous-Time Delta Sigma ADC. For this, we decided to use a Model-based design approach which it is adopted to address problems associated with designing complex control and signal processing systems such as the case of Continuous-Time Delta Sigma ADC. The goal of our study is the design of a 10 bit ENOB ADC for energy measurement systems used in particle identification through a new generation of detectors based on diamond. Results of the synthesis of a proposed fifth order Continuous-Time Delta Sigma ADC modulator for 10-bit ENOB ADC based on a Cascaded Resonators Feedforward architecture and simulations of the dispersion of its components (due to fabrication process) using the proposed tool are demonstrated and discussed.