SBOS875B August   2017  – July 2018 THS3491

PRODUCTION DATA.  

  1. Features
  2. Applications
  3. Description
    1.     Device Images
      1.      Typical Arbitrary Waveform Generator Output Drive Circuit
      2.      Harmonic Distortion vs Frequency
  4. Revision History
  5. Device Comparison Table
  6. Pin Configuration and Functions
    1.     Pin Functions
  7. Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics: VS = ±15 V
    6. 7.6 Electrical Characteristics: VS = ±7.5 V
    7. 7.7 Typical Characteristics: ±15 V
    8. 7.8 Typical Characteristics: ±7.5 V
  8. Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Power-Down (PD) Pin
      2. 8.3.2 Power-Down Reference (REF) Pin
      3. 8.3.3 Internal Junction Temperature Sense (TJ_SENSE) Pin
    4. 8.4 Device Functional Modes
      1. 8.4.1 Wideband Noninverting Operation
      2. 8.4.2 Wideband, Inverting Operation
      3. 8.4.3 Single-Supply Operation
      4. 8.4.4 Maximum Recommended Output Voltage
  9. Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Driving Capacitive Loads
      2. 9.1.2 Video Distribution
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
      1. 11.1.1 PowerPAD™ Integrated Circuit Package Design Considerations (DDA Package Only)
        1. 11.1.1.1 PowerPAD™ Integrated Circuit Package Layout Considerations
        2. 11.1.1.2 Power Dissipation and Thermal Considerations
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Community Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

Wideband Noninverting Operation

The THS3491 is a 900-MHz current-feedback operational amplifier that is designed to operate from a power supply of ±7 V to ±16 V.

Figure 61 shows the THS3491 in a noninverting gain configuration of 5 V/V which is used to generate the majority of the performance curves. Most of the curves are characterized using signal sources with a 50-Ω source impedance and measurement equipment presenting a 50-Ω load impedance.

THS3491 ths3491-rgt-noninverting-gain.gifFigure 61. Wideband Noninverting Gain Configuration (5 V/V)

Current-feedback amplifiers are highly dependent on the RF feedback resistor for maximum performance and stability. Table 2 shows the optimal resistor values for RF and RG at different gains to achieve maximum bandwidth with minimal peaking in the frequency response. Use lower RF values for higher bandwidth. Note that this can cause additional peaking and a reduction in phase margin. Conversely, increasing RF decreases the bandwidth but phase margin increases and stability improves. To gain further insight on the feedback and stability analysis of current-feedback amplifiers like the THS3491, see the Current-feedback Amplifiers section of TI Precision Labs.

Table 2. Recommended Resistor Values for Minimum Peaking and Optimal Frequency Response
With RLOAD = 100 Ω

GAIN (V/V) RGT PACKAGE DDA PACKAGE
RG (Ω) RF (Ω) RG (Ω) RF (Ω)
2 976 976 2.1k 2.1k
5 143 576 200 798
10 54.9 499 78.7 704
20 20 383 29.4 564