- 积分
- 2860
- 在线时间
- 1357 小时
- 最后登录
- 2024-5-1
- 阅读权限
- 100
- 精华
- 0
  
- UID
- 838909
- 帖子
- 2941
- 精华
- 0
- 经验
- 2860 点
- 金钱
- 2809 ￥
- 注册时间
- 2017-10-4
|
2) 平衡输入。标准单运放差分输入级如图9所示。与仪器仪表工作不同，超高CMRR通常是不必要的。普通的1%电阻和不调整的情况下，共模抑制比（CMRR）不会超过45 dB；但对于高质量音频工作来说，这通常已经足够了。
任何一个输入悬空都是绝对不能接受的，因为这会导致噪声、嗡嗡声等严重恶化。将冷输入本地接地以产生不平衡输入是很好的选择，但自然会失去所有平衡噪声抑制性能。热输入可以在本地接地，冷输入可以驱动，以产生反相输入，从而在其他位置校正相位误差，但这不是一个好做法，正确的做法是理清原始相位误差。
http://www.douglas-self.com/ampins/balanced/balanced.htm
2) Balanced inputs. A standard one-op-amp differential input stage is shown in Fig 9. Unlike instrumentation work, a super-high CMRR is usually unnecessary. Ordinary 1% resistors and no trimming will not give CMRR better than 45 dB; however this is usually adequate for even high-quality audio work.
It is never acceptable to leave either input floating, as this will cause serious deterioration of noise, hum etc. Grounding the cold input locally to create an unbalanced input is quite alright, though naturally all the balanced noise rejection is lost. The hot input can be locally grounded instead, and the cold input driven, to create a phase- inverting input that will correct a phase error elsewhere, but this is not good practice- the right thing to do is to sort out the original phase error.
http://www.douglas-self.com/ampins/balanced/balanced.htm |
|
发表于 2023-10-7 17:01
楼主
