SLOS358C September   2011  – April 2020 THS4531

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
    1. 2.1 1 kHz FFT Plot on Audio Analyzer
  3. 3 Description
  4. 4 Revision History
  5. 5 Packaging and Ordering Information
  6. 6 Electrical Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 Thermal Information
    3. 6.3 Electrical Characteristics: VS = 2.7 V
    4. 6.4 Electrical Characteristics: VS = 5 V
  7. 7 Device Information
    1. 7.1 PIN Configurations
      1. Table 2. PIN Functions
  8. 8 Table of Graphs
  9. 9 Typical Characteristics: VS = 2.7 V
  10. 10Typical Characteristics: VS = 5 V
  11. 11Application Information
    1. 11.1 Typical Characteristics Test Circuits
      1. 11.1.1 Frequency Response and Output Impedance
      2. 11.1.2 Distortion
      3. 11.1.3 Slew Rate, Transient Response, Settling Time, Overdrive, Output Voltage, and Turn-On and Turn-Off Time
      4. 11.1.4 Common-Mode and Power Supply Rejection
      5. 11.1.5 VOCM Input
      6. 11.1.6 Balance Error
    2. 11.2 Application Circuits
      1. 11.2.1  Differential Input to Differential Output Amplifier
      2. 11.2.2  Single-Ended Input to Differential Output Amplifier
      3. 11.2.3  Differential Input to Single-Ended Output Amplifier
      4. 11.2.4  Input Common-Mode Voltage Range
      5. 11.2.5  Setting the Output Common-Mode Voltage
      6. 11.2.6  Single-Supply Operation
      7. 11.2.7  Low Power Applications and the Effects of Resistor Values on Bandwidth
      8. 11.2.8  Driving Capacitive Loads
      9. 11.2.9  Audio Performance
      10. 11.2.10 Audio On and Off Pop Performance
    3. 11.3 Audio ADC Driver Performance: THS4531 AND PCM4204 Combined Performance
    4. 11.4 SAR ADC Performance
      1. 11.4.1 THS4531 and ADS8321 Combined Performance
      2. 11.4.2 THS4531 and ADS7945 Combined Performance
    5. 11.5 EVM and Layout Recommendations
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Third-Party Products Disclaimer
    2. 12.2 Documentation Support
    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

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メカニカル・データ（パッケージ｜ピン）
サーマルパッド・メカニカル・データ
発注情報

11.2.7 Low Power Applications and the Effects of Resistor Values on Bandwidth

The THS4531 is designed for the nominal value of RF to be 2 kΩ. This gives excellent distortion performance, maximum bandwidth, best flatness, and best pulse response. It also loads the amplifier. For example, in gain of 1 with RF = RG = 2 kΩ, RG to ground, and VOUT+ = 4 V, 1 mA of current will flow through the feedback path to ground. In low power applications, it is desirable to reduce this current by increasing the gain setting resistors values. Using larger value gain resistors has two primary side effects (other than lower power) due to their interaction with the device and PCB parasitic capacitance:

  1. Lowers the bandwidth.
  2. Lowers the phase margin
    1. This will cause peaking in the frequency response.
    2. And will cause over shoot and ringing in the pulse response.

Figure 76 shows the small signal frequency response for gain of 1 with RF and RG equal to 2 kΩ, 10 kΩ, and 100 kΩ. The test was done with RL = 2 kΩ. Due to loading effects of RL, lower values may reduce the peaking, but higher values will not have a significant effect.

As expected, larger value gain resistors cause lower bandwidth and peaking in the response (peaking in frequency response is synonymous with overshoot and ringing in pulse response).

THS4531 G067_Gain_vs_Freq_RF.pngFigure 76. THS4531 Frequency Response with Various Gain Setting Resistor Values