LTC5536 Ver la hoja de datos (PDF) - Linear Technology
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LTC5536 Datasheet PDF : 12 Pages
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LTC5536
APPLICATIO S I FOR ATIO
Higher Frequency Operation
Operation of the LTC5536 at higher frequencies, to 12GHz
or above, is possible with reduced performance. Figure 4
plots the VM switching voltage vs RFIN input power with a
12GHz RF input. Consult factory for more information.
High Speed Design Techniques
As with all high speed comparators, careful attention to
printed circuit board layout and design is important in
order to ensure signal integrity. The most common prob-
lem involves insufficient power supply bypassing. Bypass
capacitors should be placed as close as possible to the
LTC5536 VCC pin. A good high frequency capacitor, such
as a 100pF ceramic, is recommended, in parallel with a
larger capacitor (e.g., 0.1µF).
Avoid ground bounce problems by proper attention to
grounding, including the use of a low impedance ground
plane. If necessary, edge transition time at the comparator
output, VOUT, may be increased by means of an output
R-C low pass filter.
Poor trace routes and high source impedances are also
common sources of problems. Keep all trace lengths as
short as possible and avoid running the output trace close
to the VM or the LEN traces on the PC board. Also, keep the
VM source impedance low and decouple the VM pin with an
appropriate capacitor if necessary.
80
150mV
70
60
50
40
115mV
30
20
VCC = 3.6V
FALLING 350
TA = 25°C
EDGE
OUTPUT LOAD TO GROUND:
300
SHUNT R = 1kΩ, C = 10pF
250
VM = 200mV
115mV
200
150mV
150
VM = 200mV 100
10
RISING 50
EDGE
0
0
–18 –14 –10 –6 –2 2 6 10
RF INPUT POWER (dBm)
5536 F02
Figure 2. Propagation Delay vs RF Input Power
RFIN
INPUT
SIGNAL
RF INPUT = 2dBm
1000MHz,
ASK MODULATED
VOUT
OUTPUT
SIGNAL
100ns/DIV
2V/DIV
VM = 200mV
VCC = 3.6V
OUTPUT LOAD
(TO GROUND):
SHUNT R = 1k
5536 F03 SHUNT C = 10pF
Figure 3. Propagation Delay Example
5536f
9
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