SNAS518J July   2011  – July 2015 ADC12D1800RF


  1. Device Overview
    1. 1.1 Features
    2. 1.2 Applications
    3. 1.3 Description
    4. 1.4 Functional Block Diagram
  2. Revision History
  3. Pin Configuration and Functions
    1. 3.1 Pin Diagram
      1. 3.1.1 Pin Functions
  4. Specifications
    1. 4.1  Absolute Maximum Ratings
    2. 4.2  ESD Ratings
    3. 4.3  Recommended Operating Conditions
    4. 4.4  Thermal Information
    5. 4.5  Converter Electrical Characteristics: Static Converter Characteristics
    6. 4.6  Converter Electrical Characteristics: Dynamic Converter Characteristics
    7. 4.7  Converter Electrical Characteristics: Analog Input / Output and Reference Characteristics
    8. 4.8  Converter Electrical Characteristics: I-Channel to Q-Channel Characteristics
    9. 4.9  Converter Electrical Characteristics: Sampling Clock Characteristics
    10. 4.10 Converter Electrical Characteristics: AutoSync Feature Characteristics
    11. 4.11 Converter Electrical Characteristics: Digital Control and Output Pin Characteristics
    12. 4.12 Converter Electrical Characteristics: Power Supply Characteristics
    13. 4.13 Converter Electrical Characteristics: AC Electrical Characteristics
    14. 4.14 Converter Electrical Characteristics: Serial Port Interface
    15. 4.15 Converter Electrical Characteristics Calibration
    16. 4.16 Typical Characteristics
  5. Detailed Description
    1. 5.1 Overview
      1. 5.1.1 RF Performance
    2. 5.2 Functional Block Diagram
    3. 5.3 Feature Description
      1. 5.3.1 Input Control and Adjust
        1. AC/DC-coupled Mode
        2. Input Full-Scale Range Adjust
        3. Input Offset Adjust
        4. DES Timing Adjust
        5. Sampling Clock Phase (Aperture) Delay Adjust
      2. 5.3.2 Output Control and Adjust
        1. SDR / DDR Clock
        2. LVDS Output Differential Voltage
        3. LVDS Output Common-Mode Voltage
        4. Output Formatting
        5. Test Pattern Mode
        6. Time Stamp
      3. 5.3.3 Calibration Feature
        1. Calibration Control Pins and Bits
        2. How to Execute a Calibration
        3. Power-on Calibration
        4. On-command Calibration
        5. Calibration Adjust
        6. Read / Write Calibration Settings
        7. Calibration and Power-Down
        8. Calibration and the Digital Outputs
      4. 5.3.4 Power Down
    4. 5.4 Device Functional Modes
      1. 5.4.1 DES/Non-DES Mode
      2. 5.4.2 Demux/Non-Demux Mode
    5. 5.5 Programming
      1. 5.5.1 Control Modes
        1. Non-Extended Control Mode
          1.  Dual Edge Sampling Pin (DES)
          2.  Non-Demultiplexed Mode Pin (NDM)
          3.  Dual Data Rate Phase Pin (DDRPh)
          4.  Calibration Pin (CAL)
          5.  Calibration Delay Pin (CalDly)
          6.  Power Down I-channel Pin (PDI)
          7.  Power Down Q-channel Pin (PDQ)
          8.  Test Pattern Mode Pin (TPM)
          9.  Full-Scale Input Range Pin (FSR)
          10. AC / DC-Coupled Mode Pin (VCMO)
          11. LVDS Output Common-mode Pin (VBG)
        2. Extended Control Mode
          1. The Serial Interface
    6. 5.6 Register Maps
      1. 5.6.1 Register Definitions
  6. Application and Implementation
    1. 6.1 Application Information
      1. 6.1.1 Analog Inputs
        1. Acquiring the Input
        2. Driving the ADC in DES Mode
        3. FSR and the Reference Voltage
        4. Out-of-Range Indication
        5. Maximum Input Range
        6. AC-Coupled Input Signals
        7. DC-Coupled Input Signals
        8. Single-Ended Input Signals
      2. 6.1.2 Clock Inputs
        1. CLK Coupling
        2. CLK Frequency
        3. CLK Level
        4. CLK Duty Cycle
        5. CLK Jitter
        6. CLK Layout
      3. 6.1.3 LVDS Outputs
        1. Common-mode and Differential Voltage
        2. Output Data Rate
        3. Terminating Unused LVDS Output Pins
      4. 6.1.4 Synchronizing Multiple ADC12D1800RFS in a System
        1. AutoSync Feature
        2. DCLK Reset Feature
      5. 6.1.5 Recommended System Chips
        1. Temperature Sensor
        2. Clocking Device
        3. Amplifiers for Analog Input
        4. Balun Recommendations for Analog Input
    2. 6.2 Typical Application
      1. 6.2.1 RF Sampling Receiver
      2. 6.2.2 Design Requirements
      3. 6.2.3 Detailed Design Procedure
      4. 6.2.4 Application Curves
  7. Power Supply Recommendations
    1. 7.1 System Power-on Considerations
      1. 7.1.1 Power-on, Configuration, and Calibration
      2. 7.1.2 Power-on and Data Clock (DCLK)
  8. Layout
    1. 8.1 Layout Guidelines
      1. 8.1.1 Power Planes
      2. 8.1.2 Bypass Capacitors
      3. 8.1.3 Ground Planes
      4. 8.1.4 Power System Example
    2. 8.2 Layout Example
    3. 8.3 Thermal Management
  9. Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Specification Definitions
      2. 9.1.2 Third-Party Products Disclaimer
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 Community Resources
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 Glossary
  10. 10Mechanical, Packaging, and Orderable Information



7 Power Supply Recommendations

7.1 System Power-on Considerations

There are a couple important topics to consider associated with the system power-on event including configuration and calibration, and the Data Clock.

7.1.1 Power-on, Configuration, and Calibration

Following the application of power to the ADC12D1800RF, several events must take place before the output from the ADC12D1800RF is valid and at full performance; at least one full calibration must be executed with the device configured in the desired mode.

Following the application of power to the ADC12D1800RF, there is a delay of tCalDly and then the Power-on Calibration is executed. This is why it is recommended to set the CalDly Pin via an external pull-up or pull-down resistor. This ensured that the state of that input will be properly set at the same time that power is applied to the ADC and tCalDly will be a known quantity. For the purpose of this section, it is assumed that CalDly is set as recommended.

The Control Bits or Pins must be set or written to configure the ADC12D1800RF in the desired mode. This must take place via either Extended Control Mode or Non-ECM (Pin Control Mode) before subsequent calibrations will yield an output at full performance in that mode. Some examples of modes include DES/Non-DES Mode, Demux/Non-demux Mode, and Full-Scale Range.

The simplest case is when device is in Non-ECM and the Control Pins are set by pull-up / down resistors, see Figure 7-1. For this case, the settings to the Control Pins ramp concurrently to the ADC voltage. Following the delay of tCalDly and the calibration execution time, tCAL, the output of the ADC12D1800RF is valid and at full performance. If it takes longer than tCalDly for the system to stabilize at its operating temperature, it is recommended to execute an on-command calibration at that time.

Another case is when the FPGA configures the Control Pins (Non-ECM) or writes to the SPI (ECM), see Figure 7-2. It is always necessary to comply with the Operating Ratings and Absolute Maximum ratings, i.e. the Control Pins may not be driven below the ground or above the supply, regardless of what the voltage currently applied to the supply is. Therefore, it is not recommended to write to the Control Pins or SPI before power is applied to the ADC12D1800RF. As long as the FPGA has completed writing to the Control Pins or SPI, the Power-on Calibration will result in a valid output at full performance. Once again, if it takes longer than tCalDly for the system to stabilize at its operating temperature, it is recommended to execute an on-command calibration at that time.

Due to system requirements, it may not be possible for the FPGA to write to the Control Pins or SPI before the Power-on Calibration takes place, see Figure 7-3. It is not critical to configure the device before the Power-on Calibration, but it is critical to realize that the output for such a case is not at its full performance. Following an On-command Calibration, the device will be at its full performance.

ADC12D1800RF 30164364.gifFigure 7-1 Power-on with Control Pins set by Pull-up / down Resistors
ADC12D1800RF 30164365.gifFigure 7-2 Power-on with Control Pins set by FPGA pre Power-on Cal
ADC12D1800RF 30164366.gifFigure 7-3 Power-on with Control Pins set by FPGA post Power-on Cal

7.1.2 Power-on and Data Clock (DCLK)

Many applications use the DCLK output for a system clock. For the ADC12D1800RF, each I- and Q-channel has its own DCLKI and DCLKQ, respectively. The DCLK output is always active, unless that channel is powered-down or the DCLK Reset feature is used while the device is in Demux Mode. As the supply to the ADC12D1800RF ramps, the DCLK also comes up, see this example from the ADC12D1800RFRB: Figure 7-4. While the supply is too low, there is no output at DCLK. As the supply continues to ramp, DCLK functions intermittently with irregular frequency, but the amplitude continues to track with the supply. Much below the low end of operating supply range of the ADC12D1800RF, the DCLK is already fully operational.

ADC12D1800RF 30164390.gifFigure 7-4 Supply and DCLK Ramping