PCB新聞 - 類比電路pcb設計中應注意的12個問題

類比電路的設計是工程師們頭疼的問題, 但這也是設計的致命部分! 總結了類比電路中應注意的問題 電路設計 和你分享.

(1) In order to obtain a 迴響PCB電路 穩定性好, 通常需要在迴響回路外使用一個小電阻器或扼流圈，為電容性負載提供緩衝.

(2) The integral feedback circuit usually requires a small resistor (about 560 ohms) in series with each integral capacitor larger than 10pF.

(3) Do not use active circuits to filter or control the RF bandwidth of EMC outside the feedback loop, but only use passive components (preferably RC circuits). 積分迴響方法僅在運算放大器的開環增益大於閉環增益的頻率下有效. 在更高的頻率下, 積分器電路無法控制頻率回應.

(4) In order to obtain a stable linear circuit, all connections must be protected by passive filters or other suppression methods (such as photoelectric isolation).

(5) Use EMC filters, 所有與集成電路相關的濾波器應連接到局部0V基準面.

(6) Input and output filters should be placed at the connection of the external cable, 由於天線效應，非遮罩系統內的任何接線都需要過濾. 此外, 在具有數位信號處理或開關模式的變流器遮罩系統內的接線處也需要濾波.

(7) High-quality RF decoupling is required on the power and ground reference pins of analog ICs, 與數位積體電路相同. 但類比集成電路通常需要低頻電源去耦, because the power supply noise rejection ratio (PSRR) of analog components increases very little after being higher than 1KHz. RC或LC濾波應用於每個運算放大器的類比功率跟踪, 比較器和資料轉換器. 電力濾波器的轉角頻率應補償裝置的PSRR轉角頻率和斜率，以在整個工作頻率範圍內獲得所需的PSRR.

(8) For high-speed analog signals, 根據連接長度和通信頻率高，傳輸線科技是必要的. 即使是低頻訊號, 使用傳輸線科技可以提高其抗干擾效能, 但是，不正確匹配的傳輸線將產生天線效應.

(9) Avoid using high-impedance inputs or outputs, 對電場非常敏感.

(10) Since most of the radiation is generated by common-mode voltage and current, 因為大多數環境電磁干擾是由共模問題引起的, balanced transmission and reception (differential mode) technology is used in analog circuits It will have a good EMC effect and can reduce crosstalk. The balanced circuit (differential circuit) drive will not use the 0V reference system as the return current loop, 囙此，可以避免大電流回路, 從而减少射頻輻射.

(11) The comparator must have hysteresis (positive feedback) to prevent erroneous output conversion due to noise and interference, 並防止在中斷點處出現振盪. Do not use a comparator that is faster than required (keep dV/dt在要求範圍內, as low as possible).

(12) Some analog ICs themselves are particularly sensitive to RF fields, 囙此，經常需要使用安裝在PCB上並連接到 PCB板 遮罩此類類比組件. 筆記, 確保散熱條.