SBASAL2 November   2025 ADC32RF72

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
    8. 5.8 Timing Requirements
    9. 5.9 Typical Characteristics
  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 Input Bandwidth
        2. 7.3.1.2 Background Calibration
      2. 7.3.2 ADC Channel Selection and Power Down Modes
      3. 7.3.3 Sampling Clock Input
      4. 7.3.4 SYSREF
        1. 7.3.4.1 SYSREF Monitor
      5. 7.3.5 Digital Signal Processor (DSP) Features
        1. 7.3.5.1 DSP Input Mux
        2. 7.3.5.2 Fractional Delay
        3. 7.3.5.3 Programmable FIR Filter for Equalization
        4. 7.3.5.4 DSP Output Mux
        5. 7.3.5.5 Digital Down Converter (DDC)
          1. 7.3.5.5.1 Decimation Filter Input
          2. 7.3.5.5.2 Decimation Modes
          3. 7.3.5.5.3 Decimation Filter Response
          4. 7.3.5.5.4 Numerically Controlled Oscillator (NCO)
            1. 7.3.5.5.4.1 NCO Update
            2. 7.3.5.5.4.2 NCO RESET
      6. 7.3.6 Digital Output Interface
        1. 7.3.6.1 JESD204B/C Interface
          1. 7.3.6.1.1 JESD204B Initial Lane Alignment (ILA)
          2. 7.3.6.1.2 SYNC Signal
          3. 7.3.6.1.3 JESD204B/C Frame Assembly
          4. 7.3.6.1.4 JESD204B/C Frame Assembly in Bypass Mode
          5. 7.3.6.1.5 JESD204B/C Frame Assembly With Real Decimation
          6. 7.3.6.1.6 JESD204B,C Frame Assembly With Complex Decimation
        2. 7.3.6.2 JESD Output Reference Clock
    4. 7.4 Device Functional Modes
      1. 7.4.1 Device Operating Mode Comparison
    5. 7.5 Programming
      1. 7.5.1 GPIO Control
      2. 7.5.2 SPI Register Write
      3. 7.5.3 SPI Register Read
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application: Spectrum Analyzer
      1. 8.2.1 Design Requirements
        1. 8.2.1.1 Input Signal Path: Wideband Receiver
        2. 8.2.1.2 Clocking
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Sampling Clock Requirements
      3. 8.2.3 Application Performance Plots
    3. 8.3 Typical Application: Time Domain Digitizer
      1. 8.3.1 Design Requirements
        1. 8.3.1.1 Input Signal Path: Time Domain Digitizer
      2. 8.3.2 Application Performance Plots
    4. 8.4 Initialization Set Up
    5. 8.5 Power Supply Recommendations
    6. 8.6 Layout
      1. 8.6.1 Layout Guidelines
      2. 8.6.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Documentation Support
      1. 9.1.1 Related Documentation
      2. 9.1.2 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
7.3.5.5.4 Numerically Controlled Oscillator (NCO)

FS = ADC sampling rate (MSPS)

Each digital down-converter (DDC) uses a 48-bit numerically controlled oscillator (NCO) to fine tune the frequency placement prior to the digital filtering as shown in Figure 7-30. The NCO frequency range is -FS/2 to FS/2 and is dictated by a frequency control word (FCW) and phase offset.

There are two different NCO frequencies for each DDC. The desired NCO frequency is programmed via SPI and can be selected using SPI or the GPIO pins. When using the GPIO pins for NCO frequency control, frequency hopping can be achieved in less than 1µs.

ADC32RF72 NCO block diagram with all control signalsFigure 7-30 NCO block diagram with all control signals
Infinite Phase Coherent NCO: With a phase coherent NCO, all frequencies are synchronized to a single event using SYSREF. This enables an infinite amount of frequency hops without the need to reset the NCO as phase coherency is maintained between frequency hops. This is illustrated in Figure 7-31 (right). When returning to the original frequency f1, the NCO phase appears as if the NCO had never changed frequencies.
ADC32RF72 Infinite Phase Coherent NCO Frequency SwitchingFigure 7-31 Infinite Phase Coherent NCO Frequency Switching

The oscillator generates a complex exponential sequence of: ejωn (default) or e–jωn

where: frequency (ω) is specified as a signed number by the 48-bit FCW

The complex exponential sequence is multiplied with the real input from the ADC to mix the desired carrier to a frequency equal to fIN + fNCO. The NCO frequency can be tuned from –FS/2 to +FS/2 and is processed as a signed, 2s complement number.

The FCW setting is set by the 48-bit register value given and calculated as:

Equation 3. NCO frequency (0 to + FS/2): NCO = fNCO × 248 / FS
Equation 4. NCO frequency (-FS/2 to 0): NCO = (fNCO + FS) × 248 / FS

where:

  • NCO = FCW (decimal value)
  • fNCO = Desired NCO frequency (MHz)
  • FS = ADC sampling rate (MSPS)