SBOS394E November   2007  – July 2019 VCA824

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Differential Equalizer
      2.      Differential Equalization of an RC Load
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
    1.     Pin Functions
  7. 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 = ±5 V
    6. 7.6 Typical Characteristics: VS = ±5 V, AVMAX = 2 V/V
    7. 7.7 Typical Characteristics: VS = ±5 V, AVMAX = 10 V/V
    8. 7.8 Typical Characteristics: VS = ±5 V, AVMAX = 40 V/V
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
    4. 8.4 Device Functional Modes
      1. 8.4.1 Maximum Gain Of Operation
      2. 8.4.2 Output Current And Voltage
      3. 8.4.3 Input Voltage Dynamic Range
      4. 8.4.4 Output Voltage Dynamic Range
      5. 8.4.5 Bandwidth
      6. 8.4.6 Offset Adjustment
      7. 8.4.7 Noise
      8. 8.4.8 Input and ESD Protection
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Difference Amplifier
      2. 9.1.2 Differential Equalizer
      3. 9.1.3 Differential Cable Equalizer
      4. 9.1.4 Voltage-Controlled Lowpass Filter [application sub]
      5. 9.1.5 Wideband Variable Gain Amplifier Operation
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
      3. 9.2.3 Application Curve
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
      1. 11.1.1 Thermal Considerations
    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 Demonstration Boards
    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

9.1.1 Difference Amplifier

Because both inputs of the VCA824 are high-impedance, a difference amplifier can be implemented without any major problem. Figure 65 shows this implementation. This circuit provides excellent common-mode rejection ratio (CMRR) as long as the input is within the CMRR range of –2.1 V to 1.6 V. Note that this circuit does not make use of the gain control pin, VG. Also, it is recommended to choose RS such that the pole formed by RS and the parasitic input capacitance does not limit the bandwidth of the circuit. Figure 66 shows the common-mode rejection ratio for this circuit implemented in a gain of 10 V/V for VG = 1 V. Note that because the gain control voltage is fixed and is normally set to 1V, the feedback element can be reduced in order to increase the bandwidth. When reducing the feedback element, make sure that the VCA824 is not limited by common-mode input voltage, the current flowing through RG, or any other limitation described in this data sheet.

VCA824 ai_diff_amp_bos394.gifFigure 65. Difference Amplifier
VCA824 ai_cmrr_bos394.gifFigure 66. Common-Mode Rejection Ratio
VCA824 ai_in_out_adj_bos394.gifFigure 67. Adjusting the Input and Output Voltage Sources
VCA824 ai_simple_noise_bos394.gifFigure 68. Simple Noise Model
VCA824 ai_full_noise_bos394.gifFigure 69. Full Noise Model