SBOS780C March   2016  – June 2021 THS3215

PRODUCTION DATA  

  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Pin Configuration and Functions
  6. Specifications
    1. 6.1  Absolute Maximum Ratings
    2. 6.2  ESD Ratings
    3. 6.3  Recommended Operating Conditions
    4. 6.4  Thermal Information
    5. 6.5  Electrical Characteristics: D2S
    6. 6.6  Electrical Characteristics: OPS
    7. 6.7  Electrical Characteristics: D2S + OPS
    8. 6.8  Electrical Characteristics: Midscale (DC) Reference Buffer
    9. 6.9  Typical Characteristics: D2S + OPS
    10. 6.10 Typical Characteristics: D2S Only
    11. 6.11 Typical Characteristics: OPS Only
    12. 6.12 Typical Characteristics: Midscale (DC) Reference Buffer
    13. 6.13 Typical Characteristics: Switching Performance
    14. 6.14 Typical Characteristics: Gain Drift
  7. Parameter Measurement Information
    1. 7.1 Overview
    2. 7.2 Frequency Response Measurement
    3. 7.3 Harmonic Distortion Measurement
    4. 7.4 Noise Measurement
    5. 7.5 Output Impedance Measurement
    6. 7.6 Step-Response Measurement
    7. 7.7 Feedthrough Measurement
    8. 7.8 Midscale Buffer ROUT Versus CLOAD Measurement
  8. Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Differential to Single-Ended Stage (D2S) With Fixed Gain of 2 V/V (Pins 2, 3, 6, and 14)
      2. 8.3.2 Midscale (DC) Reference Buffer (Pin 1 and Pin 15)
      3. 8.3.3 Output Power Stage (OPS) (Pins 4, 7, 9, 10, 11, and 12)
        1. 8.3.3.1 Output DC Offset and Drift for the OPS
        2. 8.3.3.2 OPS Harmonic Distortion (HD) Performance
        3. 8.3.3.3 Switch Feedthrough to the OPS
        4. 8.3.3.4 Driving Capacitive Loads
      4. 8.3.4 Digital Control Lines
    4. 8.4 Device Functional Modes
      1. 8.4.1 Full-Signal Path Mode
        1. 8.4.1.1 Internal Connection With Fixed Common-Mode Output Voltage
        2. 8.4.1.2 Internal Connection With Adjustable Common-Mode Output Voltage
        3. 8.4.1.3 External Connection
      2. 8.4.2 Dual-Output Mode
      3. 8.4.3 Differential I/O Voltage Mode
  9. Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Typical Applications
        1. 9.1.1.1 High-Frequency, High-Voltage, Dual-Output Line Driver for AWGs
          1. 9.1.1.1.1 Design Requirements
          2. 9.1.1.1.2 Detailed Design Procedure
          3. 9.1.1.1.3 Application Curves
        2. 9.1.1.2 High-Voltage Pulse-Generator
          1. 9.1.1.2.1 Design Requirements
          2. 9.1.1.2.2 Detailed Design Procedure
          3. 9.1.1.2.3 Application Curves
        3. 9.1.1.3 Single-Supply, AC-Coupled, Piezo Element Driver
          1. 9.1.1.3.1 Detailed Design Procedure
        4. 9.1.1.4 Output Common-Mode Control Using the Midscale Buffer as a Level Shifter
          1. 9.1.1.4.1 Detailed Design Procedure
        5. 9.1.1.5 Differential I/O Driver With independent Common-Mode Control
          1. 9.1.1.5.1 Detailed Design Procedure
  10. 10Power Supply Recommendations
    1. 10.1 Thermal Considerations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Development Support
        1. 12.1.1.1 TINA-TI (Free Software Download)
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    3. 12.3 Receiving Notification of Documentation Updates
    4. 12.4 Support Resources
    5. 12.5 Trademarks
    6. 12.6 Electrostatic Discharge Caution
    7. 12.7 Glossary
  13. 13Mechanical, Packaging, and Orderable Information
Detailed Design Procedure

An easy way to insert a dc offset into the signal channel (without sacrificing any of the DAC dynamic range) is to apply the desired offset at VMID_IN (pin 1) and use it to bias VREF (pin 14) and VIN+ (pin 9). An example is shown in Figure 9-10. This example shows a relatively low maximum differential input of 1 VPP on any compliance voltage required by the DAC. Other configuration options include:

  1. The D2S output is offset using a dc input at VMID_IN. Although shown here as ±2 V, the dc range expands to ±3.5 V when using ±7.5 V supplies.
  2. Connect VMID_OUT (pin 15) to the VREF input to place the D2S output at the dc offset voltage along with a gain of 2 V/V version of the differential input voltage. The stated range of ±2 V, along with the ±0.5 V out of the upper input buffer, requires a peak output current from VMID_OUT of 2.5 V / 150 Ω = 16.7 mA. This value is well below the rated minimum linear output current of 40 mA for the midscale buffer.
  3. The dc offset voltage is then applied to the external OPS non-inverting input, VIN+. Connecting the circuit in this manner results in no additional dc gain for the dc offset between the D2S and OPS outputs, while continuing to retain the signal gain of the OPS configured as an inverting amplifier. The values of RF and RG in this application example are derived from Table 8-3. The OPS is setup for a gain of –4 V/V in this example. Using the resistor values from Table 8-3 results in the widest bandwidth for the OPS; however, the RG = 51.1 Ω resistor presents a heavy load to the D2S output. In such cases, the OPS external resistors can be scaled up to reduce the D2S output load, but at the expense of reduced OPS bandwidth.
  4. No filtering is shown in this example; however, introducing filtering in the OPS RG path is certainly possible. In such cases, the RG element is also the filter termination resistor. Filtering adds insertion loss that can be recovered by adjusting the OPS gain setting.