ACE600003 - Fractional Delay Coefficient Generator

DATASHEET

Overview 

The ACE600003 is a deterministic, real‑time fractional‑delay engine that synthesizes a complete 21‑tap Blackman‑windowed sinc kernel directly in hardware with fixed 350‑cycle latency. 

Designed for wideband, sub‑sample alignment in demanding signal‑processing pipelines, the core delivers analytical interpolation accuracy without LUTs, polynomial approximations, or multi‑phase FIR banks.

At its core is a fully unrolled mathematical pipeline: a hardware CORDIC computes the base trigonometric terms, followed by optimized scaling and 21 parallel divisions to evaluate the exact sinc response for any fractional delay in the range 01. 

A built‑in delta‑kernel bypass guarantees numerically stable behavior near the removable singularities of the sinc function, ensuring clean, well‑conditioned output across the entire delay domain.

The ACE600003 integrates through a simple dual‑port BRAM interface, avoiding AXI and eliminating protocol overhead. 

The control model is deterministic and race‑free:

• write delay → wait fixed latency → read 21 coefficients.

• Only 80 BRAM locations are reserved, leaving the remainder of the memory fully available to the user.

• Engineered for radar, beamforming, digital communications, high‑speed motion control, and other timing‑critical systems, the ACE600003 provides laboratory‑grade interpolation fidelity with an exceptionally compact footprint: <4600 LUTs, 4 DSP48E2 slices, and 1 BRAM36 on UltraScale+. The 200 MHz compute pipeline closes timing with >2.5 ns slack post‑route, enabling multi‑channel deployment even on resource‑constrained devices.

• By combining analytical precision, deterministic execution, and minimal resource usage, the ACE600003 brings high‑end fractional‑delay capability into FPGA‑class real‑time environments, enabling precise timing alignment and wideband spectral integrity without architectural compromises.

Design Customization & Portability 

The ACE600003 architecture is modular, equation‑centric, and designed for long‑term adaptability across devices, bandwidth requirements, and application domains. While the default configuration implements a 21‑tap Blackman‑windowed sinc interpolator with analytical coefficient synthesis, the core can be tailored by ACE to meet specialized performance, resource, or integration constraints. 

Algorithmic Scaling 

ACE supports a range of algorithmic adaptations to match application‑specific spectral or temporal requirements:

• Alternative window functions (Hann, Kaiser, Dolph–Chebyshev) to tune stopband attenuation, main‑lobe width, or ripple characteristics. (Already included in the present version)

• Extended tap counts for ultra‑wideband interpolation or narrowband precision where long impulse responses are required.

• Fixed‑delay or multi‑delay batch computation modes for beamforming, phased‑array timing, or systems requiring simultaneous coefficient sets.

These options allow the interpolation kernel to be shaped precisely to the customer’s signal chain and spectral budget.

Resource Optimization 

For deployments where area, power, or device class impose strict constraints, ACE offers reduced‑complexity configurations:

• Reduced‑tap architectures for ultra‑low‑footprint designs.

• Minimal‑area builds with optional removal of bypass logic or CORDIC scaling when application conditions permit.

These variants preserve deterministic timing while minimizing LUT, DSP, and BRAM usage.

Cross Platform Portability 

The core’s equation‑driven design enables straightforward migration across FPGA families and vendors:

• AMD/Xilinx: UltraScale+, Versal, 7‑Series

• Intel/Altera: Cyclone, Arria, Stratix

• Lattice: ECP5, CertusPro‑NX

• Microchip: PolarFire, RT PolarFire

The architecture avoids vendor‑specific primitives wherever possible, ensuring consistent behavior and predictable timing across platforms.

Bespoke Mathematical Models 

For customers with non‑standard interpolation requirements, ACE can integrate:

• custom window functions

• proprietary fractional‑delay models

• application‑specific coefficient shaping

• multi‑rate or multi‑phase interpolation schemes

This flexibility allows the ACE600003 to serve as a foundation for both commercial and defense‑grade signal‑processing pipelines.

Applications 

The ACE600003 is designed for real‑time signal‑processing systems that require precise sub‑sample timing, wideband spectral integrity, and deterministic execution. 

By synthesizing analytical sinc coefficients in hardware with fixed 350‑cycle latency, the core enables high‑performance fractional‑delay correction in environments where polynomial or LUT‑based interpolators introduce unacceptable jitter, bandwidth loss, or quantization artifacts. 

Key Application Benefits 

Deterministic Timing for Safety‑Critical Systems  

Applications that depend on precise inter‑channel timing benefit directly from the core’s deterministic fractional‑delay synthesis:

• digital beamforming and phased‑array steering

• multi‑axis motion‑control and servo synchronization

• coherent multi‑channel acquisition systems

The analytical kernel ensures consistent phase behavior across the full Nyquist band, enabling stable alignment even in tightly coupled control loops.

Wideband Fractional Delay Correction  

Systems requiring accurate delay adjustment over large bandwidths leverage the core’s true sinc interpolation:

• radar and sonar range‑cell alignment

• high‑speed communications timing recovery

• scientific instrumentation with wideband sampling paths

The 21‑tap Blackman‑windowed kernel preserves amplitude and phase fidelity without the bandwidth collapse typical of Farrow architectures or the extensive memory usage of the LUT‑based approach.

Low-Latency Interpolation Pipelines 

The fixed 1.75 µs execution time enables fractional‑delay correction in latency‑sensitive architectures:

• ultra‑low‑latency audio and acoustic processing

• embedded control loops with microsecond‑class update rates

• real‑time resampling and sample‑rate conversion stages

The unrolled pipeline guarantees jitter‑free behavior regardless of the requested delay.

Multi‑Channel and Resource-Constrained Systems  

The compact footprint (<4600 LUTs, 4 DSPs, 1 BRAM36) allows integrators to deploy multiple interpolators in parallel:

• multi‑beam radar/sonar front‑ends

• phased‑array timing networks

• distributed sensing and synchronization systems

Deterministic timing and minimal resource usage make the ACE600003 suitable for both high‑density FPGA fabrics and resource‑limited devices.

Seamless Integration  

The dual‑port BRAM interface presents the core as a simple memory‑mapped peripheral. No AXI, DMA, or protocol logic is required. The user writes a fractional delay, waits a fixed latency, and reads back 21 coefficients.

Numerical Robustness  

Automatic delta‑kernel bypass ensures stable behavior near the sinc singularity, guaranteeing clean, well‑conditioned output even at extreme fractional delays. 

Typical Use cases 

• Digital beamforming and phased‑array timing

• Radar and sonar fractional‑delay correction

• High‑speed motion‑control and servo synchronization

• Sample‑rate conversion and resampling pipelines

• Ultra‑low‑latency audio/communications processing

• Multi‑channel timing alignment in embedded systems

• Scientific instrumentation requiring sub‑sample precision

The ACE600003 core implements a fully analytical, wideband fractional‑delay algorithm based on the classical Blackman‑windowed sinc interpolation model. For each requested fractional delay , the engine synthesizes a complete 21‑tap FIR kernel using the exact mathematical expression:

h[n] = sinc(n + τ) * w[n]

where:

• n=-10... 10 are the tap indices

• τ ∈ [0 1) is the fractional delay (normalized to the sampling period)

• w[n] are the Blackman window coefficients ensuring wideband spectral performance

This formulation preserves amplitude and phase accuracy across the full Nyquist band and avoids the bandwidth collapse typical of polynomial (Farrow) or LUT‑based interpolators.

The computation proceeds in three conceptual stages:

Analytical Sinc Evaluation

For each tap index n, the core evaluates the exact sinc term:

sinc(n + τ) = sin( π * (n + τ) ) / ( π * (n + τ) )

This ensures mathematically correct behavior for all fractional delays, with no approximations, tables, or polynomial expansions.

Window Application

Each sinc value is multiplied by the corresponding Blackman coefficient:

h[n] = sinc(n + τ) * w[n]

The Blackman window provides:

• excellent sidelobe suppression

• smooth spectral roll‑off

• minimal interpolation ripple

This produces a wideband, high‑fidelity interpolation kernel suitable for demanding signal‑processing applications.

Edge‑Case Bypass (Delta Kernel Mode)

Near the removable singularities at 0 and 1, the sinc denominator approaches zero.

To guarantee numerical stability, the ACE600003 automatically engages a delta‑kernel bypass:

• 0: h[0] = 1, all other taps = 0

• 1: h[−1] = 1, all other taps = 0

This ensures perfectly conditioned behavior at the edges of the delay domain, with no amplification of rounding noise.

In addition, the logic has a hard clip on the maximum coefficient to 1.0 (0x40000000), avoiding any subsequent overflow in the customer FIR in case of lack of internal precision in proximity of the edge cases threshold. 

Normalization Policy

The ACE600003 generates interpolation kernels without per‑kernel normalization. This is an intentional architectural decision that preserves the deterministic timing profile and minimal resource footprint of the core.

A normalization pass would require:

• a full‑kernel reduction to compute the normalization factor

• a second pass to scale all 21 taps

• additional pipeline stages and storage

These operations introduce data‑dependent latency, increase area, and break the fixed 350‑cycle execution guarantee. Because the Blackman‑windowed sinc model inherently maintains bounded amplitude variation, normalization provides no meaningful improvement in wideband fractional‑delay applications. 

Technical Characteristics 

The ACE600003 Real‑Time Wideband Sinc Interpolator is engineered for deterministic, high‑fidelity fractional‑delay synthesis with a minimal FPGA footprint. The core delivers fixed‑latency coefficient generation at 200 MHz, enabling sub‑sample timing alignment in wideband signal‑processing pipelines without the overhead of multi‑phase FIR banks or polynomial Farrow structures. 

Resource Utilization 

The core is exceptionally compact for a 21‑tap analytical sinc engine:

• LUTs: < 4,600

• Registers: < 5,700

• DSP48E2: 4

• BRAM36: 1

• Clocking: 1 MMCM, 2 BUFGCE, 1 BUFGCE_DIV

This footprint enables multi‑channel instantiation even on the smallest UltraScale+ devices and leaves the majority of DSP and memory resources available for downstream processing.

Clocking & Timing Closure 

The ACE600003 operates with a single performance‑critical clock domain.

All analytical computations, coefficient synthesis, and BRAM Port B transactions run at:

• FAST Clock: 200 MHz (mandatory, internal)

A secondary, non‑critical clock is used only for device identification:

• SLOW Clock: user‑selectable frequency for the DNA_PORTE2 primitive (this clock has no impact on solver timing or throughput)

The user‑facing BRAM interface is intentionally decoupled from the solver domain:

• BRAM Port A:

  • fully asynchronous to the core

  • may run at any user‑defined frequency

  • not part of timing closure

  • no constraints or assumptions imposed by the IP

• BRAM Port B:

  • driven internally at 200 MHz

  • used for reading the fractional delay and writing back the 21 coefficients

  • fully synchronous to the solver pipeline

Post‑route timing analysis confirms:

All constraints met in the 200 MHz domain

WNS > 2.5 ns in the computational pipeline

No CDC violations, as all crossings are internally synchronized

No timing dependency on the user’s BRAM Port A clock

This architecture guarantees deterministic, placement‑independent timing while giving integrators complete freedom on the user‑side memory interface. 

Execution Latency & Throughput 

The solver utilizes a deep, non-iterative pipeline to provide absolute determinism in its response.

• Core Latency: Exactly 350 Clock Cycles from command to result availability (on the B PORT of the BRAM used as user interface).

• Execution Time: 1750 ns (@ 200 MHz Core Clock).

• Maximum Refresh Rate: ~570 kHz.

Jitter-Free Performance: Because the analytical path is unrolled, the latency remains constant regardless of delay that the coefficients have to implement. 

Clock Domain Crossing (CDC) Integrity 

The core features a native asynchronous bridge between the User I/O and the Compute Core:

• Interface Domain: The choice to use a BRAM as interface leaves the user the possibility to use a clock frequency of choice

• Compute Domain: 200 MHz (Higher frequencies are possible, but not tested).

• Security Domain: 50 MHz (Limited by the DNA primitive maximum speed)

Integrity: All inter-clock paths are hardware-interlocked to prevent metastability and data collisions during simultaneous memory access. 

Interfaces and operation flow 

The ACE600003 core is packaged as an AMD IP core. The picture below shows the block used in its verification project.

The core is managed entirely via read/write operations on a BRAM with AXI interface. The instantiated BRAM is a True Dual Port with port A available to the user and port B managed by the internal Math Engine.

The BRAM has a width of 32 bits and a  depth of 128 locations. The core only uses the first 80 (0 to 79) locations, with the remaining ones completely available for the user via port A (port B is assigned to the internal Math Engine).

The memory Map is reported below:

In addition to the BRAM interface, the core exposes:

• Two clock slave interfaces:

  • CLK_SLOW is used for the access to the DNA reader primitive (max frequency 100MHz, suggested frequency 50MHz)

  • CLK_FAST is used to drive the internal computation engine (suggested frequency 200MHz)

• A BUSY pin that, when set to high, signals when the core is executing the initialization or its main function. 

At start up, the core automatically performs an initialization that lasts (with CLK_SLOW @ 50 MHz and CLK_FAST @ 200MHz) less than 5000 ns. 

When the initialization is complete, the BRAM is populated with the DNA (63 downto 0) of the FPGA (addresses 76 and 77 with MSB and LSB respectively).

Once the initialization is complete, the user may load the BRAM in accordance with the input reported in the  memory map and,finally, set the START_CMD to 0x1.

The results are written in BRAM, in accordance with the memory map, after the specified latency. The end of execution is communicated by the core by setting the START_CMD to 0x0 and via the BUSY PIN (when the core sets the BUSY PIN to 0 is in IDLE state, ready for the new execution).

When the START_CMD is asserted, the core performs the entire computation, without possibility to be stopped. Writing on the BRAM addresses 1 to 79 during the execution might compromise the final results and it is, therefore, deprecated, however, regardless of any data corruption, the core terminates its execution in the specified time frame  

Note: if the USER_KEY is not correct, the core terminates in the specified timeframe, but produces unpredictable results. 

Licensing & Ordering Information 

ACE600003 is delivered as a pre‑packaged Vivado IP core, ready for integration through the AMD/Xilinx IP Catalog.

Each licensed core includes:

• Pre‑packaged Vivado IP (compatible with IP Catalog) including simulation model

• Memory map documentation (available in this datasheet)

• USER_KEY file for license activation

• Example project for rapid integration

ACE provides a USER_KEY value (64 bits) for FPGA Serial Number (DNA for AMD/Xilinx).

The keys are delivered in a simple csv file (a template is reported below):

The user may store the file with all the SN/licenses and select the key to load after reading the SN of the FPGA from the BRAM_PORTA interface of the ACE600003 core.

The envisioned process is the following:

1. The file with the keys is embedded the customer software

2. The customer software, waiting at least 5000 ns from power on, reads the FPGA SN from the BRAM_PORTA interface exposed by the  ACE600003 core (addresses 76 and 77).

3. The customer software retrieves the USER_KEY corresponding to the FPGA SN in the ACE provided USER_KEY file.

4. The customer software loads the USER_KEY via the BRAM_PORTA interface exposed by the  ACE600003 core (addresses 78 and 79).

The keys are generated on customer order.

In simulation, a demo DNA is used and the corresponding USER_KEY is provided in the file for a seamless experience.

Pricing 

Pricing is provided directly by ACE based on:

• Deployment volume

• License type

• Optional customization requirements

• Target FPGA family

Customers may request a quotation by providing their expected deployment profile and FPGA device list.