SBAS988 November   2023 ADC34RF55

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 (Dither DISABLED)
    8. 5.8  Electrical Characteristics - AC Specifications (Dither ENABLED)
    9. 5.9  Timing Requirements
    10. 5.10 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Analog Inputs
        1. 6.3.1.1 Input Bandwidth and Full-Scale
        2. 6.3.1.2 Input Imbalance
        3. 6.3.1.3 Over Range Indication
        4. 6.3.1.4 Analog out-of-band dither
      2. 6.3.2 Sampling Clock Input
      3. 6.3.3 ADC Foreground Calibration
        1. 6.3.3.1 Calibration Control
        2. 6.3.3.2 ADC Switch
        3. 6.3.3.3 Calibration Configuration
      4. 6.3.4 SYSREF
        1. 6.3.4.1 SYSREF Capture Detection
      5. 6.3.5 Decimation Filter
        1. 6.3.5.1 Decimation Filter Response
        2. 6.3.5.2 Decimation Filter Configuration
        3. 6.3.5.3 20-bit Output Mode
        4. 6.3.5.4 Numerically Controlled Oscillator (NCO)
        5. 6.3.5.5 NCO Frequency Programming Using the SPI Interface
        6. 6.3.5.6 Fast Frequency Hopping
          1. 6.3.5.6.1 Fast frequency hopping using the GPIO1/2 pins
          2. 6.3.5.6.2 Fast frequency hopping using GPIO1/2, SEN and SDATA pins
          3. 6.3.5.6.3 Fast frequency hopping using the fast SPI
      6. 6.3.6 JESD204B Interface
        1. 6.3.6.1 JESD204B Initial Lane Alignment (ILA)
          1. 6.3.6.1.1 SYNC Signal
        2. 6.3.6.2 JESD204B Frame Assembly
          1. 6.3.6.2.1 JESD204B Frame Assembly in Bypass Mode
          2. 6.3.6.2.2 JESD204B Frame Assembly with Real Decimation - Single Band
          3. 6.3.6.2.3 JESD204B Frame Assembly with Complex Decimation - Single Band
          4. 6.3.6.2.4 JESD204B Frame Assembly with Decimation - Dual Band
        3. 6.3.6.3 SERDES Output MUX
      7. 6.3.7 Test Pattern
        1. 6.3.7.1 Transport Layer
        2. 6.3.7.2 Link Layer
        3. 6.3.7.3 Internal Capture Memory Buffer
    4. 6.4 Device Functional Modes
      1. 6.4.1 Bypass Mode
      2. 6.4.2 Digital Averaging
    5. 6.5 Programming
      1. 6.5.1 GPIO Pin Control
      2. 6.5.2 Configuration using the SPI interface
        1. 6.5.2.1 Register Write
        2. 6.5.2.2 Register Read
    6. 6.6 Register Maps
      1. 6.6.1 Detailed Register Description
  8. 7 Application Information Disclaimer
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 Wideband RF Sampling Receiver
      2. 7.2.2 Design Requirements
        1. 7.2.2.1 Input Signal Path
        2. 7.2.2.2 Clocking
      3. 7.2.3 Detailed Design Procedure
        1. 7.2.3.1 Sampling Clock
      4. 7.2.4 Application Curves
    3. 7.3 Initialization Set Up
      1. 7.3.1 Initial Device Configuration After Power-Up
        1. 7.3.1.1  STEP 1: RESET
        2. 7.3.1.2  STEP 2: Device Configuration
        3. 7.3.1.3  STEP 3: JESD Interface Configuration (1)
        4. 7.3.1.4  STEP 4: SYSREF Synchronization
        5. 7.3.1.5  STEP 5: JESD Interface Configuration (2)
        6. 7.3.1.6  STEP 6: Analog Trim Settings
        7. 7.3.1.7  STEP 7: Calibration Configuration
        8. 7.3.1.8  STEP 8: SYSREF Synchronization
        9. 7.3.1.9  STEP 9: Run Power up Calibration
        10. 7.3.1.10 Step 10: JESD Interface Synchronization
        11. 7.3.1.11 Step 11: NCO Configuration
    4. 7.4 Power Supply Recommendations
    5. 7.5 Layout
      1. 7.5.1 Layout Guidelines
      2. 7.5.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Device Support
      1. 8.1.1 Third-Party Products Disclaimer
    2. 8.2 Receiving Notification of Documentation Updates
    3. 8.3 Support Resources
    4. 8.4 Trademarks
    5. 8.5 Electrostatic Discharge Caution
    6. 8.6 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

Package Options

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

6.3.5 Decimation Filter

The ADC34RF55 provides up to two digital down converters per ADC channel (see Figure 6-23). The decimation filters provide a flexible option to cover a wide range of instantaneous bandwidths (IBW) as shown in Table 6-15. Single band decimation supports a wide bandwidth up to complex decimation by 4 while up to two narrow band channels with up to 128x complex decimation are supported in dual band decimation mode.

GUID-3AD3E3BA-8AA5-4891-B472-73B0B0439E07-low.gifFigure 6-23 Digital Decimation Filter Options
Table 6-15 Summary of Different Decimation Filter Band Options

No.

of DDCs		Minimum Complex DecimationMaximum Complex Decimation
14128
28128

The decimation filter can be configured to two different operating modes:

  • Complex Decimation: This mode provides complex output with ~ 80% passband bandwidth using a 48-bit phase coherent NCO.

    During the complex mixing operation the digital output is reduced by 6-dB. This reduces the full scale from 0-dBFS to -6-dBFS. This 6-dB change applies to signals and noise and thus no dynamic range is lost.

  • Real Decimation: In real decimation mode, the complex mixer is bypassed (NCO is set to 0 for lowest power consumption), and the digital filter acts as a low pass filter. There is no frequency shifting and the output passband bandwidth is approximately 40%.

Since the JESD204B interface is common across all ADC channels, the decimation ratio as well as the number of DDCs and ADC has to be the same across all ADC channels.

By default the output of values of the decimation filter are rounded to 16-bit resolution. To avoid quantization noise limitation when using high order of decimation (that is, /64 or /128), a special 32-bit output mode can be enabled (see Section 6.3.5.3).

Table 6-16 provides an overview of the available complex decimation settings and resulting complex and real output bandwidths. Note that some of the lower decimation settings requires a reduced sampling rate due to output bandwidth limitation of the JESD204B interface.

Table 6-16 Decimation Setting vs Output Bandwidth
Decimation Factor N (complex)Complex Output Bandwidth per DDCFS = 3 GspsReal Output Bandwidth per DDCFS = 3 Gsps
Complex Output Rate per DDCComplex Output Bandwidth per DDCReal Output Rate per DDCReal Output Bandwidth per DDC
4(1)0.8 x FS / 4650 Msps520 MHz0.4 x FS / 4750 Msps300 MHz
80.8 x FS / 8375 Msps300 MHz0.4 x FS / 8375 Msps150 MHz
160.8 x FS / 16187.5 Msps150 MHz0.4 x FS / 16187.5 Msps75 MHz
320.8 x FS / 3293.75 Msps75 MHz0.4 x FS / 3293.75 Msps37.5 MHz
640.8 x FS / 6446.875 Msps37.5 MHz0.4 x FS / 6446.875 Msps18.75 MHz
1280.8 x FS / 12823.4375 Msps18.75 MHz0.4 x FS / 12823.4375 Msps9.375 MHz
(1) Limited to 2.6 GSPS in complex decimation.