TDC-GPX acam messelectronic gmbh, TDC-GPX Datasheet - Page 27

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

Derating by
Voltage
Temperature
Process
2.9 Differential Inputs
It is possible to use the differential inputs also in I-
Mode. Setting register 6, InSelECL= ‘1’ switches the
measurement channels to the two available differential
inputs.
The power for the differential inputs has to be
switched on separately by setting register 6, Power-
OnECL = ‘1’.
2.10 I-Mode Timing & Resolution
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
With a typical resolution of 81 ps (typ. process, 25°C,
3.3 V) you get 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),
The standard deviation (1 ) of the result is typically
0.9 LSB + 2,5ps * t/µs.
Resolution
Hit FIFOs 1, 2 …or/and 8 are full
Interface FIFOs 1, 2 …or/and 8 are full
PLL not locked
acam-messelectronic gmbh - Am Hasenbiel 27 - D-76297 Stutensee-Blankenloch - Germany - www.acam.de
Minimal
0.91 at 3.6V
0.889 at –40°C
0.74 at BC
Best
64 ps
Worst
113 ps
Maximal
1.2 at 2.85V
1.17 at +125°C
1.31 at WC
27
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 strongly
systematic. The following diagram shows the DNL data
at a resolution of 74 ps:
INL
The integral non-linearity describes the deviation over
the full measuring range. The INL of the TDC-GPX for a
single Start-Stop measurement with a delay > 6 ns is
below our measurement capability and can be ne-
glected. In the close-up region below 6 ns the deviation
is about 100 ps.
100
90
80
70
60
50
40
30
20
10
0
1,6
1,4
1,2
0,8
0,6
0,4
0,2
1
0
0,0
I-Mode, Standard deviation, TTL-inputs
2,0
Figure 22: DNL
TDC-GPX: DNL, I-Mode
Figure 21
4,0
Delay t (µs)
Bin
TDC-GPX
6,0
8,0
10,0