TDC-GPX acam messelectronic gmbh, TDC-GPX Datasheet - Page 42

• Manufacturer Part Number: TDC-GPX
• Description: Precision Time Interval Measurement
• Manufacturer: acam messelectronic gmbh

The on-chip timings for measuring rising and falling
edge down to 1.5 ns are very critical. For some chips
it might be necessary to add an internal, additional
delay to guarantee correct data processing. These
delays are set by the RaSpeed bits and the Del-
Risex/DelFallx/DelTx in registers 2, 3 and 4. Increas-
ing those will reduce the pulse-pair resolution of the
TDC-GPX .
4.11 R-Mode Timing & Resolution
TDC-GPX is working in resolution adjust mode. The
resolution adjust unit is identical with TDC-F1’s unit.
The delay parameters vary with voltage, temperature
and process tolerance. The following table lists the
derating factors.
With the stabilization of the resolution by the resolu-
tion adjust mode, the voltage of the core decreases
with decreasing temperature, and increases with in-
creasing temperature. The setting should be done in a
way that at maximum operating temperature the
maximum core voltage is reached, and that minimum
core voltage is reached at minimum operating tem-
perature. With this method you get two limits:
Best case process, deepest temperature, lowest volt-
age: 0.74 x 0.889 x 1.2 = 0.789
Worst case process, highest temperature, highest
voltage: 1.31 x 1.17 x 0.91 = 1.394
From validation measurement the typical BIN size has
been 27 ps (typ. process, 25°C, 3.3V). With the above-
mentioned derating factors this gives two limits for the
resolution:
The BIN or LSB width is defined by the setting of the
resolution adjust unit (1.6.1 Resolution adjust),
Derating by
Voltage
Temperature
Process
Resolution
RaSpeed & Delx
acam-messelectronic gmbh - Am Hasenbiel 27 - D-76297 Stutensee-Blankenloch - Germany - www.acam.de
4
0
1
2
3
Minimal
0.91 at 3.6V
0.889 at –
40°C
0.74
Best
21 ps
Pulse-pair resolution
8.5 ns
5.5 ns
6.5 ns
7.5 ns
8.5 ns
Worst
38 ps
Maximal
1.2 at 2.85V
1.17 at
+125°C
1.31
42
Figure 32
The standard deviation (1 ) of the result is typically
1.4 LSB + 2,8 ps * t/µs.
The pulse width limit is 1.5 ns typically, limited by the
input buffers.
The measurement range depends on the bin size and
the coarse counter. Its typical value is:
Measurement range
DNL
The TDC-GPX shows a moderate differential non-
linearity (DNL) because internal propagation delays
were used for the time measurement and because
those delays are different for rising and falling edges,
but the variation from channel to channel is system-
atic. The following diagram shows the DNL data at a
resolution of 27 ps:
35
30
25
20
15
10
5
0
7
6
5
4
3
2
1
0
0,0
5,0
10,0
R-Mode, Standard deviation, TTL-inputs
TDC-GPX: DNL, R-Mode
15,0
Figure 31
= 54 x 32767 x 27 ps
= 47 µs
20,0
Delay t (µs)
BIN
25,0
TDC-GPX
30,0
35,0
40,0
45,0