am working on tdc1000 for that am generating 40Khz clock but am getting spikes how can remove it suggest me an solution if any one got solution

First make sure the spikes are real and not being generated in your scope lead. They can be generated at this frequency by the inductance of the lead or any long wire. They can be reduced by adding a low seriese resistor about 470R, or by a higher value of pull up resistor on the line.

And how are you generating the 40kHz?