We would like to interface to a TDC7201 for short range distance measurements, using optical technology as ultrasound is not possible in our application.
The distance measurement range is 8 cm to 150cm with about 1.5cm accuracy, which is appears to be within the measurement capability of the TDC7201. However, to achieve good precision requires very fast rise times on the STOP inputs, which are single ended. High speed transimpedance amplifiers with integrated gain resistors are fast and have low jitter (e.g. MAX3658), but have differential outputs with insufficient output swing. Following the transimpedance amp with a comparator is possible, but single ended comparators have slower rise times than differential ones and compromise the accuracy. Using a linear amp such as an LMH6629 has lower gain, and adding more gain stages would add jitter and to variability.
Any suggestions for a very fast interface between a photodiode and the TDC7201 would be appreciated.
Thanks
Bernard
