SBASAL3 September   2024 ADC3669

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1  Absolute Maximum Ratings
    2. 5.2  ESD Ratings
    3. 5.3  Recommended Operating Conditions
    4. 5.4  Thermal Information
    5. 5.5  Electrical Characteristics - Power Consumption
    6. 5.6  Electrical Characteristics - DC Specifications
    7. 5.7  Electrical Characteristics - AC Specifications (ADC3668 - 250 MSPS)
    8. 5.8  Electrical Characteristics - AC Specifications (ADC3669 - 500 MSPS)
    9. 5.9  Timing Requirements
    10. 5.10 Typical Characteristics, ADC3668
    11. 5.11 Typical Characteristics, ADC3669
  7. 6 Parameter Measurement Information
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Analog Inputs
        1. 7.3.1.1 Nyquist Zone Selection
        2. 7.3.1.2 Analog Front End Design
      2. 7.3.2 Sampling Clock Input
      3. 7.3.3 Multi-Chip Synchronization
        1. 7.3.3.1 SYSREF Monitor
      4. 7.3.4 Time-Stamp
      5. 7.3.5 Overrange
      6. 7.3.6 External Voltage Reference
      7. 7.3.7 Digital Gain
      8. 7.3.8 Decimation Filter
        1. 7.3.8.1 Uncommon Decimation Ratios
        2. 7.3.8.2 Decimation Filter Response
        3. 7.3.8.3 Decimation Filter Configuration
        4. 7.3.8.4 Numerically Controlled Oscillator (NCO)
      9. 7.3.9 Digital Interface
        1. 7.3.9.1 Parallel LVDS (DDR)
        2. 7.3.9.2 Serial LVDS (SLVDS) with Decimation
        3. 7.3.9.3 Output Data Format
        4. 7.3.9.4 32-bit Output Resolution
        5. 7.3.9.5 Output MUX
        6. 7.3.9.6 Test Pattern
    4. 7.4 Device Functional Modes
      1. 7.4.1 Low Latency Mode
      2. 7.4.2 Digital Channel Averaging
      3. 7.4.3 Power Down Mode
    5. 7.5 Programming
      1. 7.5.1 GPIO Programming
      2. 7.5.2 Register Write
      3. 7.5.3 Register Read
      4. 7.5.4 Device Programming
      5. 7.5.5 Register Map
      6. 7.5.6 Detailed Register Description
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Wideband Spectrum Analyzer
      2. 8.2.2 Design Requirements
        1. 8.2.2.1 Input Signal Path
        2. 8.2.2.2 Clocking
      3. 8.2.3 Detailed Design Procedure
        1. 8.2.3.1 Sampling Clock
      4. 8.2.4 Application Performance Plots
      5. 8.2.5 Initialization Set Up
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Documentation Support
      1. 9.1.1 Third-Party Products Disclaimer
    2. 9.2 Receiving Notification of Documentation Updates
    3. 9.3 Support Resources
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

7.3.8 Decimation Filter

The ADC366x provides up to four digital down converters as shown in Figure 7-20. Using the cross point switch with SPI register writes, any of the four DDC can be connected to any ADC or the output of the 2x AVG block. In dual band mode (2 DDC), decimation from /2 to /32768 is supported. While in 4 DDC mode, the lowest decimation possible is /4 as shown in Table 7-5. 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 7-6.

ADC3668 ADC3669 Internal digital down converter Figure 7-20 Internal digital down converter
Table 7-5 Summary of different decimation filter band options
# of DDCs Min Decimation Max Decimation
2 /2 /32768
4 /4 /32768
Table 7-6 Complex decimation and real decimation vs output bandwidth
Decimation Factor (complex) Complex Output Bandwidth per DDC Real Output Bandwidth per DDC
N 0.8 x FS / N 0.4 x FS / N

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