ZHCSGP3D September   2017  – December 2018

PRODUCTION DATA.

1. 特性
2. 应用
3. 说明
4. 修订历史记录
5. Pin Configuration and Functions
6. Specifications
7. Detailed Description
1. 7.1 Overview
2. 7.2 Functional Block Diagrams
3. 7.3 Feature Description
4. 7.4 Device Functional Modes
8. Application and Implementation
1. 8.1 Application Information
2. 8.2 Typical Applications
1. 8.2.1 Active Filters
2. 8.2.2 Implementing a 2:1 Active Multiplexer
3. 8.2.3 1-Bit PGA Operation
9. Power Supply Recommendations
10. 10Layout
11. 11器件和文档支持
1. 11.1 文档支持
2. 11.2 相关链接
3. 11.3 接收文档更新通知
4. 11.4 社区资源
5. 11.5 商标
6. 11.6 静电放电警告
7. 11.7 术语表
12. 12机械、封装和可订购信息

• DCK|5
• DBV|6
• DCK|5

#### 8.1.7 Differential to Single-Ended Amplifier

Figure 78 shows a differential amplifier that converts differential signals to single-ended in a single stage and provides gain (or attenuation) and level shifting. This circuit can be used in applications such as a line receiver for converting a differential signal from a Cat5 cable to a single-ended output signal.

The output of the amplifier can be calculated according to Equation 9 if VIN+ = VCM + VSIG+ and VIN– = VCM + VSIG–.

Equation 9.

The signal gain of the circuit is shown in Equation 10, VCM is rejected, and VREF provides a level shift or reference voltage around which the output signal swings. The single-ended output signal is in-phase with the noninverting input signal. VREF is often ground when split supplies are used on the op amp.

Equation 10.

Line termination can be accomplished by adding a shunt resistor across the VIN+ and VIN– inputs. The differential impedance is the shunt resistance in parallel with the input impedance of the amplifier circuit, which is usually much higher. For low gain and low line impedance, the resistor value to add is approximately the impedance of the line. For example, if a 100-Ω Cat5 cable is used with a gain of 1 V/V amplifier and RF = RG = 2 kΩ, adding a 100-Ω shunt across the input gives a differential impedance of 99 Ω, which is an adequate match for most applications.

For best CMRR performance, resistors must be matched. Assuming CMRR ≈ the resistor tolerance, a 0.1% tolerance provides approximately 60-dB CMRR.