TIDUEU6B September   2020  – December 2021 OPA810

 

  1.   Description
  2.   Resources
  3.   Features
  4.   Applications
  5.   5
  6. 1System Description
    1. 1.1 Key System Specifications
  7. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Highlighted Products
      1. 2.2.1 OPA2810
      2. 2.2.2 BUF634A
    3. 2.3 Design Considerations
      1. 2.3.1 Existing architecture
        1. 2.3.1.1 Circuit Stability Issue
        2. 2.3.1.2 Solution in Existing Architecture (Compensation Cap)
      2. 2.3.2 Proposed Design
        1. 2.3.2.1 Stability Analysis of the Proposed Design
          1. 2.3.2.1.1 Without Measurement of Voltage at Inverting Node of A2
          2. 2.3.2.1.2 With Measuring Voltage at Inverting Node of A2
        2. 2.3.2.2 RG = RF Settings and Respective Impedance Ranges
        3. 2.3.2.3 Impedance Measurement Procedure
          1. 2.3.2.3.1 Short Cal
          2. 2.3.2.3.2 Impedance Cal
          3. 2.3.2.3.3 100k Setting Calibration
          4. 2.3.2.3.4 Open Cal
          5. 2.3.2.3.5 Calculations
          6. 2.3.2.3.6 Correction in ZX
          7. 2.3.2.3.7 Data Acquisition and Processing
          8. 2.3.2.3.8 Mathematical Explanation
  8. 3Hardware, Software, Testing Requirements, and Test Results
    1. 3.1 Required Hardware and Software
      1. 3.1.1 Hardware
    2. 3.2 Testing and Results
      1. 3.2.1 Test Setup
      2. 3.2.2 Test Results
  9. 4Design Files
    1. 4.1 Schematics
    2. 4.2 Bill of Materials
    3. 4.3 PCB Layout Recommendations
      1. 4.3.1 Layout Prints
    4. 4.4 Altium Project
    5. 4.5 Gerber Files
    6. 4.6 Assembly Drawings
  10. 5Software Files
  11. 6Related Documentation
    1. 6.1 Trademarks
    2. 6.2 Third-Party Products Disclaimer
  12. 7Revision History

3.2.1 Test Setup

  1. Short the jumper J6. It should be noted that jumper J6 is for offset calibration and not used in this design.
  2. Always keep one of the jumpers among J1, J2, J3 short according to RG – RF setting needed. This prevents the saturation of U2A.
  3. Connect both +/- 12 V and +/-15 V power supplies to J15 and J20 respectively.
  4. Set the required RG – RF setting, refer to Table 2-1 and Table 3-2 to determine and set desired connections.
  5. Do calibration of each setting at all 4 frequencies according to the calibration process explained in Section 2.3.2.3. Use Table 3-2 to make connections according to required calibration.
  6. Use the calibration results to estimate the unknown impedance as explained in Section 2.3.2.3.

Configurations for different connections on the board are given inTable 3-1

Table 3-2 Connector Configurations
CONDITIONCONNECTOR CONFIGURATION
Short CalibrationJ6 = Short, R41 = Open, R42 = Short
Open CalibrationJ6 = Open
Impedance CalibrationJ6 = Open
RG = RF =100 SettingJ1J2J3J5J7J10
ShortOpenOpenShortOpenOpen
RG = RF =5 k SettingJ1J2J3J5J7J10
OpenShortOpenOpenShortOpen
RG = RF =100 k SettingJ1J2J3J5J7J10
OpenOpenShortOpenOpenShort

Table 3-3 provides recommended operating voltages on connectors.

Table 3-3 Operating Voltages
DESCRIPTIONRECOMMENDED VOLTAGE
OPA2810 Supply (J15)+/- 12 V
BUF634A Supply (J20)+/- 15 V
VCA Supply (J16)(NOT USED)+/- 5 V