SN74LVC3G04反向放大器设计38KHz晶体电路不起振

采用SN74LVC3G04作为反向放大器，设计38KHz晶体电路，存在的问题：大概率不能起振，调整晶体匹配电容C9/12和限流电阻R18验证是无效的，即使能起振的电路板，实测晶体电路负性阻抗远远不合格，存在不能稳定起振的风险。

TI的Application Report：Use of the CMOS Unbuffered Inverter in Oscillator Circuits，里面有提到：

A CMOS inverter with a Schmitt-trigger input is not suitable for use in the oscillator circuit
described previously. A Schmitt-trigger input device has two different thresholds, and it may
not be possible to bias them properly in the linear region using the circuit described
previously.

An unbuffered inverter itself may not have enough drive for a high-capacitive load. As a
result, the output voltage swing may not be rail to rail. This also will slow down the edge rate
of the output signal. To solve these problems, a buffer or inverter with a Schmitt-trigger input
can be used at the output of the oscillator. Examples of Schmitt-trigger input buffers and
inverters are the LVC1G17 and LVC1G14.

SN74LVC3G04是buffered反向器，目前判断反向器没有工作在线性放大区，反向器型号有问题，希望得到大家的帮助，谢谢

确认是反向放大器选型错误，应采用unbuffered类型