这个电路是经过我仿真的，在仿真中第一级的直流偏置是正常的，但在实际搭建的电路上，第一级的放大输出直流偏置不正确，应该是VCC/2，但变为接近电源电压了？
这是我仿真的电路图
这是仿真的AC波形
这是仿真的DC波形
在实际电路板上的波形如下
输入信号AC波形
第一级放大AC波形
第二级放大AC波形
第一级放大DC波形
第二级放大DC波形
Hi:
I agree it looks like it's clipping, but the OP279 has rail to rail input and you only seem to be using fairly small signals, so it should not be clipping.
Are you using 10x probes, or 1x probes, or just BNC cables, to the oscilloscope? Is the oscilloscope input impedance 1M, or 50 Ohms?
I just using 1x probes and the oscilloscope input impedance is 1M.
On 2nd review, I noticed your first stage DC oscillograph has 2V/DIV and shows almost 5V of DC. I think that is your problem. Did you set up your signal generator as 2.25V, but then not terminate it with 50 Ohms? Most generators assume 50 Ohm termination, so without termination the signal is 2x too large.
I suspect that the first stage of dc has been amplified twice, and that the first stage amplifies the output close to the supply voltage when there is no signal the first stage input
the first stage output