TS8388BMFSB/QNB1 Atmel Corporation, TS8388BMFSB/QNB1 Datasheet - Page 27

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

Figure 29. Single-ended Clock Input (Ground common mode):
VCLK Common Mode = 0V; VCLKB = 0V; 4 dBm Typical Clock Input Power Level (into 50
Differential ECL Clock
Input
Figure 30. Differential Clock Inputs (ECL Levels)
2144A–BDC–04/02
-0.8V
-1.8V
+0.5V
-0.5V
[mV]
[V]
VCLK
VCLK
This is true so long as the inverted phase clock input pin is 50 terminated very closely to one
of the neighboring shield ground pins, which constitutes the local Ground reference for the
inphase clock input.
Thus the TS8388BF differential clock input buffer will fully reject the local ground noise (and
any capacitively and inductively coupled noise) as common mode effects. Moreover, a very
low phase noise sinewave generator must be used for enhanced jitter performance.
The typical inphase clock input amplitude is 1V peak to peak, centered on 0V (ground) com-
mon mode. This corresponds to a typical clock input power level of 4 dBm into the 50
termination resistor. Do not exceed 10 dBm to avoid saturation of the preamplifier input
transistors.
The inverted phase clock input is grounded through the 50 termination resistor.
Note:
The clock inputs can be driven differentially with nominal -0.8V/-1.8V ECL levels.
In this mode, a low phase noise sinewave generator can be used to drive the clock inputs, fol-
lowed by a power splitter (hybrid junction) in order to obtain 180 degrees out of phase
sinewave signals. Biasing tees can be used for offseting the common mode voltage to ECL
levels.
Note: As the biasing tees propagation times are not matching, a tunable delay line is required
in order to ensure the signals to be 180 degrees out of phase especially at fast clock rates in
the GSPS range.
Do not exceed 10 dBm into the 50 termination resistor for single clock input power level.
VCLK
VCLKB
Common mode = -1.3V
VCLK = 0V
t
t
(external)
(external)
CLK or CLKB double pad (pins 37, 38 or 39, 40)
50
CLK or CLKB double pad (pins 37, 38 or 39, 40)
CLK or CLKB
50
CLK or CLKB
-2V
50 reverse termination
50 reverse termination
termination resistor)
1 M
1 M
TS8388BF
0.4 pF
0.4 pF
27