TDC-GPX datasheet(43/54 Pages) AMSCO

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TDC-GPX

acam-messelectronic gmbh - Am Hasenbiel 27 - D-76297 Stutensee-Blankenloch - Germany - www.acam.de

8.5 ns

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 .

RaSpeed & Delx

Pulse-pair resolution

5.5 ns

6.5 ns

7.5 ns

8.5 ns

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.

Derating by

Minimal

Maximal

Voltage

0.91 at 3.6V

1.2 at 2.85V

Temperature

0.889 at –

40°C

1.17 at

+125°C

Process

0.74

1.31

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:

Best

Worst

Resolution

21 ps

38 ps

The BIN or LSB width is defined by the setting of the

resolution adjust unit (1.6.1 Resolution adjust),

The standard deviation (1

σ) of the result is typically

1.4 LSB + 2,8 ps *

∆t/µs.

R-Mode, Standard deviation, TTL-inputs

0,0

5,0

10,0

15,0

20,0

25,0

30,0

35,0

40,0

45,0

Delay

∆

∆∆

∆t (µs)

Figure 31

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

= 54 x 32767 x 27 ps

= 47 µs

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:

TDC-GPX: DNL, R-Mode

BIN

Figure 32

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