LTC5535ES6 LINER [Linear Technology], LTC5535ES6 Datasheet - Page 9

• Manufacturer Part Number: LTC5535ES6
• Description: Precision 600MHz to 7GHz, RF Detector with Adjustable Gain and 12MHz Baseband Bandwidth
• Manufacturer: LINER [Linear Technology]

APPLICATIO S I FOR ATIO
Operation
The LTC5535 RF detector integrates several functions to
provide RF power detection over frequencies ranging
from 600MHz to 7GHz. These functions include an internal
frequency compensated output amplifier, an RF Schottky
diode peak detector and a level shift amplifier to convert the
RF input signal to DC. The LTC5535 has both gain setting
and voltage offset adjustment capabilities.
Output Amplifier
The output amplifier is capable of supplying typically
20mA into a load. The negative terminal V
to a pin for gain selection. External resistors connected
between V
the gain of this amplifier.
The amplifier is not unity gain stable; a minimum gain of
two is required. The output amplifier has a bandwidth of
20MHz with a gain of 2. For increased gain applications,
the bandwidth is reduced according to the formula:
For stable operation the gain setting resistors should be
low values and the board capacitance on V
minimized. R
500Ω for all gain settings.
Gain = 1 + R
Bandwidth = 40MHz/(Gain) = 40MHz • R
OUT
B
and V
A
is recommended to be no greater than
/R
B
U
M
(R
A
) and V
U
ADJUSTMENT
M
RF
OFFSET
to ground (R
W
IN
R1
(OPT)
M
is brought out
39pF
B
C4
M
/(R
should be
U
1
2
3
B
A
LTC5535ES6
) will set
Demo Board Schematic
RF
GND
V
+ R
OS
IN
V
B
V
OUT
)
V
CC
M
6
5
4
The V
amplifier. V
output voltage is not to be changed. The output amplifier
is initially trimmed to 200mV (Gain = 2) with V
nected to ground.
The V
voltage. This function, in combination with gain adjust-
ment enables the LTC5535 output to span the input range
of a variety of analog-to-digital converters. V
change until V
V
where gain is the output amplifier gain. For a gain of 2,
V
RF Detector
The internal RF Schottky diode peak detector and level
shift amplifier converts the RF input signal to a low
frequency signal. The detector demonstrates excellent
efficiency and linearity over a wide range of input power.
The Schottky diode is biased at about 50µA and drives a
5pF internal peak detector capacitor.
OUT
OUT
V
C2
100pF
OUT
for V
will exactly track V
OS
OS
= 0.5 • V
input controls the DC input voltage to the output
R2
500Ω
1%
R3
500Ω
1%
pin is used to change the initial V
5535 DB
OS
C1
0.1µF
OS
V
2.7V TO 5.5V
GND
CC
>200mV is:
OS
must be connected to ground if the DC
OS
exceeds 200mV. The starting voltage at
R
(OPT)
LOAD
• Gain
V
OUT
OS
above 200mV.
LTC5535
OUT
OUT
OS
starting
will not
con-
9
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