LTC5507
100kHz to 1GHz
RF Power Detector
FEATURES
s
s
s
DESCRIPTIO
s
s
s
s
s
Temperature Compensated Internal Schottky
Diode RF Detector
Wide Input Power Range: –34dBm to 14dBm
Ultra Wide Input Frequency Range: 100kHz to
1000MHz
Buffered Output
Wide V
CC
Range of 2.7V to 6V
Low Operating Current: 550µA
Low Shutdown Current: <2µA
Low Profile (1mm) ThinSOT
TM
Package
The LTC
®
5507 is an RF power detector for applications
operating from 100kHz to 1000MHz. The input frequency
range is determined by an external capacitor. A tempera-
ture-compensated Schottky diode peak detector and buffer
amplifier are combined in a small 6-pin ThinSOT package.
The RF input voltage is peak detected using an on-chip
Schottky diode and external capacitor. The detected volt-
age is buffered and supplied to the V
OUT
pin. A power
saving shutdown mode reduces supply current to less
than 2µA.
, LTC and LT are registered trademarks of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technology Corporation
APPLICATIO S
s
s
s
s
Wireless Transceivers
Wireless and Cable Infrastructure
RF Power Alarm
Envelope Detector
TYPICAL APPLICATIO
Typical Detector Characteristics
at 100kHz, 100MHz and 1000MHz
10000
T
A
= 25°C
V
CC
= 2.7V TO 6V
4
V
BAT
2.7V TO 6V
C2
C1
RF
INPUT
6
5
V
CC
PCAP
RF
IN
V
OUT
GND
SHDN
5507 TA01
3
2
1
V
OUT
DETECTED
VOLTAGE
V
OUT
OUTPUT VOLTAGE (mV)
LTC5507
1000
DISABLE ENABLE
Figure 1. 100kHz to 1000MHz RF Power Detector
100
–34
–26
U
100kHz, 100MHz
1000MHz
–18
–10
–2
6
RF INPUT POWER (dBm)
14
5507 TA01b
U
U
5507f
1
LTC5507
ABSOLUTE
(Note 1)
AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
ORDER PART
NUMBER
TOP VIEW
SHDN 1
GND 2
V
OUT
3
6 RF
IN
5 PCAP
4 V
CC
V
CC
, V
OUT
to GND .................................... –0.3V to 6.5V
RF
IN
Voltage to GND ......................... (V
CC
±
1.8V) to 7V
SHDN Voltage to GND ................ –0.3V to (V
CC
+ 0.3V)
PCAP Voltage to GND ........................(V
CC
– 1.8V) to 7V
I
VOUT
...................................................................... 5mA
Operating Temperature Range (Note 2) .. – 40°C to 85°C
Maximum Junction Temperature ......................... 125°C
Storage Temperature Range ................ – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
LTC5507ES6
S6 PART
MARKING
LTZX
S6 PACKAGE
6-LEAD PLASTIC SOT-23
T
JMAX
= 125°C,
θ
JA
= 250°C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 3.6V, RF Input Signal is Off, unless otherwise noted.
PARAMETER
V
CC
Operating Voltage
I
VCC
Shutdown Current
I
VCC
Operating Current
V
OUT
V
OL
(No RF Input)
V
OUT
Output Current
V
OUT
Enable Time
V
OUT
Load Capacitance
V
OUT
Noise
SHDN Voltage, Chip Disabled
SHDN Voltage, Chip Enabled
SHDN Input Current
RF
IN
Input Frequency Range
Max RF
IN
Input Power
RF
IN
AC Input Resistance
RF
IN
Input Shunt Capacitance
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
Specifications over the –40°C to 85°C operating temperature
range are assured by design, characterization and correlation with
statistical process controls.
(Note 3)
F = 10MHz, RF Input = –10dBm
F = 1000MHz, RF Input = –10dBm
SHDN = 0V
SHDN = V
CC
, I
VOUT
= 0mA
R
LOAD
= 2k, SHDN = V
CC
, Enabled
SHDN = 0V, Disabled
V
OUT
= 1.75V, V
CC
= 2.7V to 6V,
∆V
OUT
= 10mV
SHDN = V
CC
, C
LOAD
= 33pF, R
LOAD
= 2k
(Note 4)
V
CC
= 3V, Noise BW = 1.5MHz, 50Ω RF Input Termination
V
CC
= 2.7V to 6V
V
CC
= 2.7V to 6V
SHDN = 3.6V
q
q
q
q
q
q
ELECTRICAL CHARACTERISTICS
CONDITIONS
MIN
q
q
q
TYP
MAX
6
2
UNITS
V
µA
mA
mV
mV
mA
µs
pF
mV
P-P
V
V
µA
MHz
dBm
Ω
Ω
pF
2.7
0.55
130
1
250
1
2
7
2
0.85
370
20
33
0.35
1.4
24
0.1– 1000
14
130
95
1.7
40
Note 3:
RF performance is tested at: 80MHz, –4dBm
Note 4:
Guaranteed by design.
2
U
5507f
W
U
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W W
W
LTC5507
TYPICAL PERFOR A CE CHARACTERISTICS
LTC5507 Typical Detector
Characteristics, 100kHz,
V
CC
= 2.7V TO 6V
10000
C1 = 0.47µF
C2 = 0.47µF
10000
V
OUT
OUTPUT VOLTAGE (mV)
1000
T
A
= –40°C
V
OUT
OUTPUT VOLTAGE (mV)
T
A
= 25°C
100
–34 –28 –22 –16 –10 –4
2
RF INPUT POWER (dBm)
8
14
LTC5507 Typical Detector
Characteristics, 1000MHz
V
CC
= 2.7V TO 6V
10000
POSITIVE V
OUT
SLEW RATE (V/µs)
C1 = 33pF
C2 = 33pF
V
OUT
OUTPUT VOLTAGE (mV)
1000
T
A
= –40°C
100
–34 –28 –22 –16 –10 –4
2
RF INPUT POWER (dBm)
Negative V
OUT
Slew Rate vs C2
Capacitance
10.000
NEGATIVE V
OUT
SLEW RATE (V/µs)
10000
1.000
V
OUT
BW (kHz)
0.100
0.010
0.001
0
33
330
3300
33000
C2 CAPACITANCE (pF)
U W
T
A
= 25°C
LTC5507 Typical Detector
Characteristics, 100MHz
V
CC
= 2.7V TO 6V
C1 = 1000pF
C2 = 1000pF
1000
T
A
= 85°C
T
A
= –40°C
T
A
= 85°C
T
A
= 25°C
100
–34 –28 –22 –16 –10 –4
2
RF INPUT POWER (dBm)
8
14
5507 G01
5507 G02
Positive V
OUT
Slew Rate vs C2
Capacitance
10.0
1.0
0.10
T
A
= 85°C
0.01
8
14
33
330
3300
33000
C2 CAPACITANCE (pF)
330000
5507 G04
5507 G03
V
OUT
BW vs C2 Capacitance
1000
100
10
330000
5507 G05
1
33
330
3300
33000
C2 CAPACITANCE (pF)
330000
5507 G06
5507f
3
LTC5507
PI FU CTIO S
SHDN (Pin 1):
Shutdown Input. A logic low or no-connect
on the SHDN pin places the part in shutdown mode. A logic
high enables the part. SHDN has an internal 150k pull
down resistor to ensure that the part is in shutdown when
the enable driver is in a tri-state condition.
GND (Pin 2):
System Ground.
V
OUT
(Pin 3):
Buffered and Level Shifted Detector Output
Voltage.
V
CC
(Pin 4):
Power Supply Voltage, 2.7V to 6V. V
CC
should
be bypassed with 0.1µF and 100pF ceramic capacitors.
PCAP (Pin 5):
Peak Detector Hold Capacitor. Capacitor
value is dependent on RF frequency. Capacitor must be
connected between PCAP and V
CC
.
RF
IN
(Pin 6):
RF Input Voltage. Referenced to V
CC
. A
coupling capacitor must be used to connect to the RF
signal source. This pin has an internal 250Ω termination
and an internal Schottky diode detector.
BLOCK DIAGRA
C1
RF
SOURCE
RF
IN
C2
V
CC
PCAP
5
6
GND 2
C1 = C2
C2 (µF)
≥
1
, f = LOWEST RF INPUT FREQUENCY (MHz)
30f
1
SHDN
5507 BD
4
W
U
U
U
V
CC
4
GAIN
COMPRESSION
250Ω
SHDN
+
BUFFER
3
V
OUT
–
30k
30k
100Ω
+
RF DET
–
60µA
60µA
150k
BIAS
Figure 2.
5507f
LTC5507
APPLICATIO S I FOR ATIO
Operation
The LTC5507 integrates several functions to provide RF
power detection over frequencies up to 1000MHz. These
functions include an internally compensated buffer ampli-
fier, an RF Schottky diode peak detector and level shift
amplifier to convert the RF signal to DC, a delay circuit to
avoid voltage transients at V
OUT
when coming out of shut-
down, and a gain compression circuit to extend the
detector dynamic range.
Buffer Amplifier
The buffer amplifier has a gain of two and is capable of
driving a 2mA load. The buffer amplifier typically has an
output voltage range of 0.25V to V
CC
– 0.1V.
RF Detector
The internal RF Schottky diode peak detector and level
shift amplifier converts the RF input signal to a low
frequency signal. The frequency range of the RF pin is
typically up to 1000MHz. The detector demonstrates ex-
cellent operation over a wide range of input power. The
Schottky detector is biased at about 70µA. The hold
capacitor is external.
Gain Compression
The gain compression circuit changes the feedback ratio
as the RF peak-detected input voltage increases above
60mV. Below 60mV, the DC voltage gain from the peak
detector to the buffer output is 4. Above 140mV, the DC
voltage gain is reduced to 0.75. The compression expands
the low power detector range due to higher gain.
Modes of Operation
MODE
Shutdown
Enable
SHDN
Low
High
OPERATION
Disabled
Power Detect
U
Applications
The LTC5507 can be used as a self-standing signal strength
measuring receiver for a wide range of input signals from
–34dBm to 14dBm for frequencies up to 1000MHz.
The LTC5507 can be used as a demodulator for AM and
ASK modulated signals with data rates up to 1.5MHz.
Depending on specific application needs, the RSSI output
can be split into two branches, providing AC-coupled data
(or audio) output and DC-coupled, RSSI output for signal
strength measurements and AGC.
C1, C2 Capacitor Selection (Refer to Figure 3)
C1 couples the RF input signal to the detector input RF
IN
which is referenced to V
CC
. C2 is the peak detector
capacitor connected between PCAP and V
CC
. The value of
C2 will affect the slew rate and bandwidth. Typically C1 can
equal C2. Ceramic capacitors are recommended for C1
and C2. The values for C1 and C2 are dependent on the
operating RF frequency. The capacitive reactance should
be less than 5Ω to minimize ripple on C2.
C2(µF)
≥
1/(30 • f) where f is the lowest RF input
frequency (MHz)
C1 = C2
In general, select C1 and C2 large enough to pass the
lowest expected RF signal frequency, as described by the
above formulas. But optimize C1 and C2, subject to this
constraint, to improve output slew rate and bandwidth,
and to enable good AC performance for the highest
expected RF signal frequency.
5507f
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