hosseineslahi7
Junior Member level 1
Hi All,
I have designed an analog circuit in sub-threshold the frequency of which is tunned from kHz to a few MHz range. For measurement purposes, I know that a buffer with a small output impedance is needed for each voltage node and this buffer should be added to the layout before fabrication. I have already designed a buffer showing an acceptable swing, however, I was informed that the probs, pad, and package capacitance are altogether around 15pF. Therefore, a buffer should be tested for such a big load before I add its layout to my main layout.
The problem is that the buffer cannot be loaded by this capacitor, the output bandwidth of it gets too small, and there is no signal in the output. The solution is to increase the width of transistors in the buffer but it did not work for my design.
Has anyone ever designed test points for analog measurement? Any ideas can help a lot.
Cheers,
Hossein
I have designed an analog circuit in sub-threshold the frequency of which is tunned from kHz to a few MHz range. For measurement purposes, I know that a buffer with a small output impedance is needed for each voltage node and this buffer should be added to the layout before fabrication. I have already designed a buffer showing an acceptable swing, however, I was informed that the probs, pad, and package capacitance are altogether around 15pF. Therefore, a buffer should be tested for such a big load before I add its layout to my main layout.
The problem is that the buffer cannot be loaded by this capacitor, the output bandwidth of it gets too small, and there is no signal in the output. The solution is to increase the width of transistors in the buffer but it did not work for my design.
Has anyone ever designed test points for analog measurement? Any ideas can help a lot.
Cheers,
Hossein