同样看数据手册也能看出来:
ADXL335:
Noise Density XOUT, YOUT                         150μg/√Hz rms
Noise Density ZOUT                                      300μg/√Hz rms

MMA7260:
Noise
RMS (0.1 Hz – 1 kHz)(4)                                                  nRMS 4.7mVrms
Power Spectral Density RMS (0.1 Hz – 1 kHz)(4)       nPSD 350μg√Hz

现在总算大概了解所谓"μg√Hz"是个什么效果了