SNAU308A November   2024  – May 2025

 

  1.   1
  2.   Description
  3.   Get Started
  4.   Features
  5.   Applications
  6.   6
  7. 1Evaluation Module Overview
    1. 1.1 Introduction
    2. 1.2 Kit Contents
    3. 1.3 Specification
    4. 1.4 Device Information
  8. 2Hardware
    1. 2.1 Setup
      1. 2.1.1 Evaluation Setup Requirement
      2. 2.1.2 Connection Diagram
    2. 2.2 Jumper Information
    3. 2.3 Power Requirements
    4. 2.4 Reference Clock
    5. 2.5 Output Connections
    6. 2.6 Test Points
  9. 3Software
    1. 3.1 Software Description
    2. 3.2 Software Installation
    3. 3.3 USB2ANY Interface
  10. 4Implementation Results
    1. 4.1 Evaluation Setup
    2. 4.2 Performance Data and Results
      1. 4.2.1 RF Output
      2. 4.2.2 VCO Calibration
        1. 4.2.2.1 No Assist Operation
        2. 4.2.2.2 Full Assist Operation
      3. 4.2.3 SYSREF
        1. 4.2.3.1 SYSREF Clock Generation
        2. 4.2.3.2 SYSREF Pulse Generation
        3. 4.2.3.3 SYSREF Repeater Mode
      4. 4.2.4 Phase Adjustment
      5. 4.2.5 Phase Synchronization
        1. 4.2.5.1 Category 1b and Category 2 SYNC
        2. 4.2.5.2 Category 3 SYNC
      6. 4.2.6 Pin Mode
  11. 5Hardware Design Files
    1. 5.1 Schematics
    2. 5.2 PCB Layouts
    3. 5.3 Bill of Materials (BOM)
  12. 6Additional Information
    1. 6.1 Debug Information
    2. 6.2 Trademarks
  13. 7Revision History

4.2.1 RF Output

With EVM Default Mode configuration, VCO frequency is 12GHz, RFoutA output is 6GHz.

LMX2624SPEVM LMX2695SEPEVM LMX2824EPEVM Divided Down Output Figure 4-3 Divided Down Output

Click on Output MUX and select VCO, RFoutA output becomes 12GHz.

LMX2624SPEVM LMX2695SEPEVM LMX2824EPEVM Output MUX Options Figure 4-4 Output MUX Options
LMX2624SPEVM LMX2695SEPEVM LMX2824EPEVM Direct VCO Output Figure 4-5 Direct VCO Output

To get VCO doubler output, click on Output MUX and select Doubler. A VCO doubler calibration is required to configure the internal tracking filter so that the 2x signal passes through while the sub-harmonics are suppressed. To complete the doubler calibration, set FCAL_DBLR_EN = 1 and click the Calibrate VCO button once (this programs R0).

LMX2624SPEVM LMX2695SEPEVM LMX2824EPEVM VCO Doubler Calibration Figure 4-6 VCO Doubler Calibration
LMX2624SPEVM LMX2695SEPEVM LMX2824EPEVM VCO Doubler Output Figure 4-7 VCO Doubler Output

Sub-harmonic suppression is about −52dBc at 24GHz output and −42dBc at 15GHz output.

LMX2624SPEVM LMX2695SEPEVM LMX2824EPEVM 24GHz OutputFigure 4-8 24GHz Output
LMX2624SPEVM LMX2695SEPEVM LMX2824EPEVM 15GHz OutputFigure 4-9 15GHz Output

If RFOUTA or RFOUTB is not used, output driver can be shut down by setting OUTx_PD = 1. Unused output pins can be left floating or AC-shunt to ground. Output can also be muted without shutting down the driver. Output mute is controlled by the MUTEA and MUTEB pin or configurable using SPI programming.

LMX2624SPEVM LMX2695SEPEVM LMX2824EPEVM Output Mute Control Figure 4-10 Output Mute Control

The response time of mute control using the hardware pin is very fast, typical value is 10ns.

LMX2624SPEVM LMX2695SEPEVM LMX2824EPEVM Pin Control Mute Response TimeFigure 4-11 Pin Control Mute Response Time
LMX2624SPEVM LMX2695SEPEVM LMX2824EPEVM Pin Control Unmute Response TimeFigure 4-12 Pin Control Unmute Response Time