SBAU249A October   2015  – July 2025 ADS9110

 

  1.   1
  2.   2
  3.   Trademarks
  4. 1Evaluation Module Overview
    1. 1.1 ADS9110EVM-PDK Features
    2. 1.2 ADS9110EVM Features
  5. 2Analog Interface
    1. 2.1 Connectors for Differential Signal Source
    2. 2.2 ADC Differential Input Signal Driver
      1. 2.2.1 Input Signal Path
      2. 2.2.2 Input Common-Mode Jumper Configuration
      3. 2.2.3 R1 Setting vs Source Impedance
    3. 2.3 Onboard ADC Reference
  6. 3Digital Interfaces
    1. 3.1 multiSPI® for ADC Digital IO
  7. 4Power Supplies
  8. 5 ADS9110EVM-PDK Initial Setup
    1. 5.1 Default Jumper Settings
    2. 5.2 EVM Graphical User Interface (GUI) Software Installation
  9. 6 ADS9110EVM-PDK Operation
    1. 6.1 EVM GUI Global Settings for ADC Control
    2. 6.2 Register Map Configuration Tool
    3. 6.3 Time Domain Display Tool
    4. 6.4 Spectral Analysis Tool
    5. 6.5 Histogram Tool
    6. 6.6 Linearity Analysis Tool
  10. 7Hardware Design Files
    1. 7.1 Schematics
    2. 7.2 PCB Layout
    3. 7.3 Bill of Materials
  11. 8Revision History

6.4 Spectral Analysis Tool

The spectral analysis tool is intended to evaluate the dynamic performance (SNR, THD, SFDR, SINAD, and ENOB) of the ADS9110 SAR ADC through single-tone sinusoidal signal FFT analysis using the 7-term Blackman-Harris window setting. Alternatively, the window setting of None can be used to search for noise spurs over frequency in dc inputs.

For dynamic performance evaluation, the external differentialsingle-ended source must have better specifications than the ADC to make sure that the measured system performance is not limited by the performance of the signal source. Therefore, the external reference source must meet the source requirements mentioned in Table 6-1.

Table 6-1 External Source Requirements for Evaluation of the ADS9110
Specification DescriptionSpecification Value
Signal frequency2kHz
External source typeBalanced differential
External source common-mode0V or floating
(see Section 2.2.2 for jumper settings)
External source impedance (RS)10Ω–30Ω
External source differential impedance
(RS_DIFF = 2 × RS)		20Ω–60Ω
Source differential signal
(VPP Amplitude for –0.1 dBFS)		(2 × RS × 4.45 × 10–3) + 8.9V
or
(RS_DIFF × 4.45 × 10–3) + 8.9V
Maximum noise10µVRMS
Maximum SNR110 dB
Maximum THD–130 dB

For 2kHz SNR and ENOB evaluation at a maximum throughput of 2 MSPS, the number of samples must be 32768 or 65536. More samples brings the noise floor so low that the external source phase noise can dominate the SNR and ENOB calculations. On the contrary, for THD and SFDR evaluation, a much larger number of samples must be used to reduce the noise floor below –140 dBc to analyze noise-free harmonics and spurs in the order of –120dBc. Such analysis requires at least 262144 samples.

Spectral Analysis ToolFigure 6-5 Spectral Analysis Tool

Finally, the FFT tool includes windowing options that are required to mitigate the effects of non-coherent sampling (this discussion is beyond the scope of this document). The 7-Term Blackman Harris window is the default option and has sufficient dynamic range to resolve the frequency components of up to a 24-bit ADC. Note that the None option corresponds to not using a window (or using a rectangular window) and is not recommended.