SBASAO4B December   2024  – June 2025 ADC3568 , ADC3569

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison
  6. 5 Pin Configuration and Functions
  7. 6 Specifications
    1. 6.1  Absolute Maximum Ratings
    2. 6.2  ESD Ratings
    3. 6.3  Recommended Operating Conditions
    4. 6.4  Thermal Information
    5. 6.5  Electrical Characteristics - Power Consumption
    6. 6.6  Electrical Characteristics - DC Specifications
    7. 6.7  Electrical Characteristics - AC Specifications (ADC3568 - 250 MSPS)
    8. 6.8  Electrical Characteristics - AC Specifications (ADC3569 - 500 MSPS)
    9. 6.9  Timing Requirements
    10. 6.10 Typical Characteristics, ADC3568
    11. 6.11 Typical Characteristics, ADC3569
  8. 7 Parameter Measurement Information
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Analog Input
        1. 8.3.1.1 Nyquist Zone Selection
        2. 8.3.1.2 Analog Front End Design
      2. 8.3.2 Sampling Clock
      3. 8.3.3 Multi-Chip Synchronization
        1. 8.3.3.1 SYSREF Monitor
      4. 8.3.4 Time-Stamp
      5. 8.3.5 Overrange
      6. 8.3.6 External Voltage Reference
      7. 8.3.7 Digital Gain
      8. 8.3.8 Decimation Filter
        1. 8.3.8.1 Uncommon Decimation Ratios
        2. 8.3.8.2 Decimation Filter Response
        3. 8.3.8.3 Decimation Filter Configuration
        4. 8.3.8.4 Numerically Controlled Oscillator (NCO)
      9. 8.3.9 Digital Interface
        1. 8.3.9.1 Parallel LVDS (SDR) - Default
        2. 8.3.9.2 Parallel LVDS (DDR)
        3. 8.3.9.3 SLVDS with Decimation
          1. 8.3.9.3.1 SLVDS - Status Bit Insertion
        4. 8.3.9.4 Output Data Format
        5. 8.3.9.5 32-bit Output Resolution
        6. 8.3.9.6 Output Scrambler
        7. 8.3.9.7 Output MUX
        8. 8.3.9.8 Test Pattern
    4. 8.4 Device Functional Modes
      1. 8.4.1 Low Latency Mode
      2. 8.4.2 Power Down Mode
    5. 8.5 Programming
      1. 8.5.1 GPIO Programming
      2. 8.5.2 Register Write
      3. 8.5.3 Register Read
      4. 8.5.4 Device Programming
      5. 8.5.5 Register Map
      6. 8.5.6 Detailed Register Description
  10. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Wideband Spectrum Analyzer
      2. 9.2.2 Design Requirements
        1. 9.2.2.1 Input Signal Path
        2. 9.2.2.2 Clocking
      3. 9.2.3 Detailed Design Procedure
        1. 9.2.3.1 Sampling Clock
      4. 9.2.4 Application Performance Plots
      5. 9.2.5 Initialization Set Up
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Documentation Support
      1. 10.1.1 Third-Party Products Disclaimer
    2. 10.2 Receiving Notification of Documentation Updates
    3. 10.3 Support Resources
    4. 10.4 Trademarks
    5. 10.5 Electrostatic Discharge Caution
    6. 10.6 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

8.3.8 Decimation Filter

The ADC3568 and ADC3569 provide up to four digital down converters as shown in Figure 8-21. Using the crosspoint switch with SPI register writes, any of the four DDCs can be connected. In single band mode (1 DDC), decimation from /2 to /32768 is supported. While in 4 DDC mode, the lowest decimation possible is /8 as shown in Table 8-5. Real (single band only) and complex decimation are supported. In real decimation, the passband is approximately 40% and in complex decimation the passband is approximately 80% as illustrated in Table 8-6.

ADC3568 ADC3569 Internal digital down converter Figure 8-21 Internal digital down converter
Table 8-5 Summary of different decimation filter band options
# of DDCsMin DecimationMax Decimation
1/2/32768
2/4/32768
4/8/32768
Table 8-6 Complex decimation and real decimation vs output bandwidth
Decimation Factor (complex)Complex Output Bandwidth per DDCReal Output Bandwidth per DDC
N0.8 x FS / N0.4 x FS / N

Decimation is enabled by setting the <COMMON DECIMATION> SPI register (0x169, D3-D0). By default, the register is set to 'real' decimation. 'Complex' decimation is enabled with register <COMPLEX EN> (0x162, D2).