TS8388BMFSB/QNB1 Atmel Corporation, TS8388BMFSB/QNB1 Datasheet - Page 29

• Manufacturer Part Number: TS8388BMFSB/QNB1
• Description: ADC 8-bit 1 GSPS
• Manufacturer: Atmel Corporation

2144A–BDC–04/02
Three possible line driving and back-termination scenarios are proposed (assuming V
0V):
1. 75
2. 50
3. 75
Note: This is no longer true if a 50 transmission line is used, as the latter is not matching the
buffer 75 output impedance.
Each differential output termination length must be kept identical. It is recommended to decou-
ple the midpoint of the differential termination with a 10 nF capacitor to avoid common mode
perturbation in case of slight mismatch in the differential output line lengths.
Too large mismatches (keep < a few mm) in the differential line lengths will lead to switching
currents flowing into the decoupling capacitor leading to switching ground noise.
The differential output voltage levels (75
levels, however it is possible to drive standard logic ECL circuitry like the ECLinPS logic line
from
At sampling rates exceeding 1 GSPS, it may be difficult to trigger the HP16500 or any other
Acquisition System with digital outputs. It becomes necessary to regenerate digital data and
Data Ready by means of external amplifiers, in order to be able to test the TS8388BF at its
optimum performance conditions.
Each output voltage varies between -1V and -1.42V (respectively +1.4V and +1V), leading
to
V
Each output voltage varies between -1.02V and -1.35V (respectively +1.38V and +1.05V),
leading to
mode for V
Each output voltage varies between -1.6V and -0.8V (respectively +0.8V and +1.6V),
which are true ECL levels, leading to
tively +1.2V) common mode for V
to drive directly high input impedance storing registers, without terminating the 75
mission lines. In time domain, that means that the incident wave will reflect at the 75
transmission line output and travel back to the generator (i.e.: the 75 data output buffer).
As the buffer output impedance is 75 , no back reflection will occur.
Motorola
PLUSD
±
0.41V = 0.825V in differential, around -1.21V (respectively +1.21V) common mode for
impedance transmission lines, 75 differentially terminated (Figure 32):
impedance transmission lines, 50 differentially termination (Figure 33):
impedance open transmission lines (Figure 34):
= 0V (respectively 2.4V).
®
.
±
PLUSD
0.33V = 660 mV in differential, around -1.18V (respectively +1.21V) common
= 0V (respectively 2.4V).
PLUSD
±
or 50
0.8V = 1.6V in differential, around -1.2V (respec-
= 0V (respectively 2.4V). Therefore, it is possible
termination) are not ECL standard voltage
TS8388BF
PLUSD
trans-
29
=