Tips for Analog Circuit Design (Part 1)
Analog circuit design is one of the most complicated design parts, also becomes a headache problem for most engineers. Although currently digital circuits and large-scale integrated circuit develop quickly, the analog circuit design is still inevitable, and sometimes digital circuits cannot be replaced, such as RF circuit design. The following tips are practical for your analog circuit design.
1. In order to get a stable feedback circuit, it is usually required to use a small resistor or choke outside the feedback loop to provide a buffer for the capacitive load.
2. The integral feedback circuit typically requires a small resistor (about 560 ohms) in series with each 10 pF+ integrating capacitor.
3. Do not use the RF bandwidth that is an active circuit can filter or control EMC outside the feedback loop, only passive components (RC circuit is better) can be used. The integral feedback method is effective only if the open loop gain of the op amp is greater than the closed loop gain. At higher frequencies, the integrating circuit cannot control the frequency response.
4. In order to obtain a stable linear circuit, all connections must be protected by using passive filters or other suppression methods like opto-isolated.
5. Use EMC filters or IC-related filters should be connected to the local 0V reference plane.
6. The input and output filters should be placed at the junction of the external cable, and any wire connections without the shielded system need filtering because of the antenna effect. In addition, filtering is also required at the wire connection inside the shield system of the converter which has the digital signal processing or switching mode.
To be continued…