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TDC-GP2 Measurement Range 2

Digital TDCs use internal propagation delays of signals through gates to measure time intervals with very high precision (see also measurement range 1).

  • 2 stop channels referring to one start channel
  • Each of typ. 50 ps resolution, 65 ps BIN size
  • 15 ns pulse pair resolution
  • 4-fold multihit capability for each stop channel
  • Measurement range 3.5 ns to 1,8 µs
  • Selectable rising/falling edge sensitivity for each channel
  • Enable pins for powerful windowing functionality
  • The possibility to arbitrarily measure all events against each other

In measurement range 2 the maximum time interval is extended using a pre-divider. The resolution in LSB remains unchanged by that. In this mode the high-speed unit of the TDC does not measure the whole time interval but only time intervals from START and STOP to the next rising edge of the reference clock (fine-counts). In between the fine-counts the TDC counts the number of periods of the reference clock (coarse-count).

The BIN size (LSB) is typically 65 ps at 3.6 V and 25 °C ambient temperature. The gate propagation delay times strongly depend on temperature and voltage. In measuring range 2 the result is the sum of different fine and coarse-count results. Therefore it is necessary in measuring range 2 to make a calibration. During a calibration the TDC measures 1 and 2 periods of the reference clock.

The measuring unit is actuated by a START signal and stopped by a STOP signal. Based on the position of the ring oscillator and the coarse counter the time interval between START and STOP is calculated with a 26 Bit measurement range.

The measurement range is limited by size of the coarse counter:
tyy = Tref x 16384 ~ 4 ms

Time (Condition)Description
tph2.5 nsMinimum pulse width
tpl2.5 nsMinimum pulse width
tss500 ns min.Start to Stop
trrnsRising edge to rising edge
tffnsFalling edge to falling edge
tva4.6 µs calibratedLast hit to data valid
tyy4 msMeasurement range