文氏橋振盪器 由放大器和文氏橋反饋電路組成(圖1)。放大器由兩級共發射極負反饋電路級聯而成,輸出與輸入同相。反饋電路由R1C1、R2C2串並聯而成,在某一頻率上,其輸出亦與輸入同相。兩者構成正反饋。R1C1串聯支路、R2C2並聯支路和反饋電阻Rf、R
![RC 振盪器](/img/6/95c/ml2ZuM3XxcTO0MjNxAzMxgDM5ETMwADMwADMwADMwADMxAzLzEzLxczLt92YucmbvRWdo5Cd0FmLyE2LvoDc0RHa.jpg)
![RC 振盪器](/img/b/238/nBnauM3XxkzNwQjNxAzMxgDM5ETMwADMwADMwADMwADMxAzLzEzLxkzLt92YucmbvRWdo5Cd0FmLwE2LvoDc0RHa.jpg)
K>3K
為放大電路的放大倍數,為了減小輸出波形的失真,放大器應工作線上性區;其振盪幅度由負溫度係數的熱敏電阻Rf來限制。用同軸電位器或雙聯電容器同時改變R1、R2的電阻值或C1、C2的電容量,可以連續改變振盪頻率。測量用的可變低頻信號發生器大多採用此類振盪電路。用集成式運算放大器代替電晶體構成文氏橋振盪器(圖2),可使電路結構更為簡單。
![RC 振盪器](/img/4/4d3/nBnauM3XyIDO0UjNxAzMxgDM5ETMwADMwADMwADMwADMxAzLzEzLyIzLt92YucmbvRWdo5Cd0FmLzE2LvoDc0RHa.jpg)
![RC 振盪器](/img/2/f61/nBnauM3XwUTN2YjNxAzMxgDM5ETMwADMwADMwADMwADMxAzLzEzLwUzLt92YucmbvRWdo5Cd0FmL0E2LvoDc0RHa.jpg)