i need you guy to help me on the ADC testing..so for the first step what are the things that i need to know before doing the ADC testing and what is the characteristic that usually tester check on the ADC ... Thank you (",)
do you test your circuit on chip or on the pcb board?
they are different.
if you testing on chip you should think about your probe to acquisition data,
if you testing on board ,there are more free room to design your scheme.
About the test board:
- If you use an external Vref be carefull with the buffer design. It must be able to drive the ADC without ringing. Place decoupling cap close to the Vref pin.
- Be carefull with the clock pattern. If you use an external generator and high freq (over 100MHz), I would not apply a square directly but a sine and use a LVDS circuit on board to fix it. Refer to the evaluation kits of TI, analog devices or maxim for design ideas.
Sorry for the late reply.
LVDS stands for Low-Voltage Differential Signal. It's a way to transmit logic signal at high speed. Instead of 0-VDD it uses a few hundred mV sine.
The point is that the receiver is able to transform a high frequency sine wave in a nice pulse.
If you generate directly a 100MHz pulse, the cable loss for the generator to the PCB, and the PCB traces loss are important. It's easier to transmit a 100mV sine rather than a 0-3.3V pulse.
So on the PCB you put a LVDS receiver close to your IC to transorm the sine into a pulse clock. If it's close enought to the IC pin, the loss a minimum.
Exemples of receivers are the MAX9113 (Maxim) or MC100LVEL16 (Onsemi).