JAJU844 August   2022

 

  1.   概要
  2.   リソース
  3.   特長
  4.   アプリケーション
  5.   5
  6. 1System Description
    1. 1.1 Key System Specifications
  7. 2System Overview
    1. 2.1 Schematic Diagram
    2. 2.2 Highlighted Products
      1. 2.2.1 THS3491 Current Feedback Amplifier Specifications
    3. 2.3 System Design Theory
      1. 2.3.1 Theory of Operation
        1. 2.3.1.1 Concept of Power Supply Range Extension
      2. 2.3.2 Stability Considerations
        1. 2.3.2.1 Inclusion of Series Isolation Resistance (RS)
      3. 2.3.3 Power Dissipation
        1. 2.3.3.1 DC Internal Power Dissipation of Driver Amplifier for a Purely Resistive Output Load
        2. 2.3.3.2 AC Average Internal Power Dissipation of Driver Amplifier for a Purely Resistive Output Load
        3. 2.3.3.3 Internal Average Power Dissipation of Driver Amplifier for RC Output Load
      4. 2.3.4 Thermal Performance
        1. 2.3.4.1 Linear Safe Operating Area (SOA)
  8. 3Hardware, Software, Testing Requirements, and Test Results
    1. 3.1 Required Hardware
    2. 3.2 Test Setup
    3. 3.3 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. 5Related Documentation
    1. 5.1 Trademarks

1 System Description

This design guide describes the use of three THS3491 current-feedback amplifiers in a bootstrapped power supply configuration to achieve 50-Vpp output swing capability at 1 MHz with ultra-low harmonic distortion and > 200-mA output current drive capability.

High-frequency and large-signal applications require high slew rate amplifiers for minimal signal distortion. In the case of a large capacitive load, high-output current drive is also desired. These requirements are common in applications such as an LCD and LED tester, arbitrary waveform generator, CCD panel driver, function generator, semiconductor test equipment, lab instrumentation, laser driver, LCR meter power output driver, and so forth.

The THS3491 features a class AB output stage offering low-distortion and high output current, with output headroom requirements of 1.5 V (typical) to each supply. With a maximum supply range of 32 V (±16 V), the THS3491 can drive an output voltage swing up to 29 Vpp in the typical case. This is quite high, yet in the case of an LCD tester for example, it may be desirable to extend the output swing even higher. To achieve this, two additional THS3491 are used in a supply modulation loop to extend the power supply range of the overall circuit up to 64V (±32 V). This approach allows generation of the desired 50 Vpp output pulse that is capable of driving capacitive loads seen in LCD tester applications.

The THS3491 VQFN-16 (RGT) package is chosen for the driver amplifier to attain the best large-signal bandwidth, distortion, and thermal performance possible.