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

6.3.2 Sampling Clock Input

The internal sampling clock path is designed for the lowest residual phase noise contribution. The sampling clock circuitry requires a dedicated low noise power supply for best performance. The internal residual clock phase noise is also sensitive to clock amplitude. For best performance, the clock amplitude must be larger than 1 VPP. The phase noise improves by 3 dB per 2x averaging; however, at higher input frequencies the clock path contribution reduces the improvement.

Table 6-7 Internal Aperture Clock Phase Noise
(FS = 3 Gsps, VIN = 1 VPP)
Frequency Offset (MHz)Amplitude (dBc/Hz)
0.001-117
0.01-127
0.1-137
1-147
10-154
250-160

The clock input and ADC sampling circuitry have an amplitude noise component which modulates on to the sampled input signal. Unlike phase noise, the amplitude noise does not scale with input frequency. Amplitude noise is only affected by the sampling reset switch as shown in Figure 6-10 and Figure 6-11. This noise component can dominate the close in noise performance at lower input frequencies.

GUID-20221209-SS0I-HPRR-52WD-G18TVRZCGR9J-low.svgFigure 6-10 Amplitude Noise vs Input Frequency
GUID-20221209-SS0I-NNFH-FV4R-5BWLZKHW07CJ-low.svgFigure 6-11 Amplitude and Phase noise at 10 kHz offset vs Input Frequency

The internal aperture jitter is also dependent on the amplitude of the external clock input signal. Figure 6-12 and Figure 6-13 show the expected SNR performance with dither on/off across clock amplitude (FS = 2.6 GSPS).

GUID-20231002-SS0I-VZXT-9R7W-PFHDRJR2SXS9-low.svgFigure 6-12 SNR vs Clock Amplitude (Dither OFF)
GUID-20231002-SS0I-M91J-RMWV-9XHZ8PQMHXNB-low.svgFigure 6-13 SNR vs Clock Amplitude (Dither ON)

The sampling clock input is internally terminated to 100 Ω differentially and provides a return loss better than 10 dB (see Figure 6-14). The clock input consists of a single clock input buffer followed by a dedicated clock buffer for ADCA/B as well as ADCC/D. When averaging two ADCs internally, there is some decrease in clock buffer noise which is correlated and does not improve with averaging.

GUID-BB35A8AC-F988-40D5-8A18-3C4BE640DD52-low.svgFigure 6-14 Clock Input Internal Circuitry