LT5537
Wide Dynamic Range
RF/IF Log Detector
DESCRIPTIO
The LT
®
5537 is a wide dynamic range RF/IF detector,
operational from below 10MHz to 1000MHz. The lower
limit of the operating frequency range can be extended to
near DC by the use of an external capacitor. The input
dynamic range at 200MHz with
±3dB
nonlinearity is 90dB
(from –76dBm to 14dBm, single-ended 50Ω input). The
detector output voltage slope is nominally 20mV/dB, and
the typical temperature coefficient is 0.01dB/°C at 200MHz.
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
FEATURES
■
■
■
■
■
■
■
Low Frequency to 1000MHz Operation
83dB Dynamic Range with
±1dB
Nonlinearity
at 200MHz
Sensitivity –76dBm or Better at 200MHz
Log-Linear Transfer Slope of 20mV/dB
Supply Voltage Range: 2.7V to 5.25V
Supply Current: 13.5mA at 3V
Tiny 8-Lead (3mm
×
2mm) DFN Package
APPLICATIO S
■
■
■
■
■
■
■
Linear-to-Log Signal Level Conversion
Received Signal Strength Indication (RSSI)
RF Power Control
RF/IF Power Detection
Receiver RF/IF Gain Control
Envelope Detection
ASK Receiver
TYPICAL APPLICATIO
7k
7k
OPTIONAL
4
CAP
+
5
CAP
–
15nF
RF IN
15nF
3
2
OFFSET
CANCELLATION
IN
+
IN
–
V
CC
6
1nF
1µF
V
OUT
(V)
DETECTOR CELLS
OUTPUT
BUFFER
OUT
7.2k
V
EE
8
V
CC
= ENBL = 3V
0
–80
–60
–40
–20
0
INPUT POWER (dBm)
–3
20
5537 TA01b
1
ENBL
BANDGAP REFERENCE
AND BIASING
EXPOSED PAD
9
7
5537 TA01a
U
U
U
Output Voltage, Linearity Error
vs Input Power at 200MHz
2.4
2.0
85°C
1.6
1.2
0.8
0.4
–40°C
25°C
1
0
–1
–2
3
2
5537fa
1
LINEARITY ERROR (dB)
LT5537
ABSOLUTE
(Note 1)
AXI U
RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
ENBL 1
IN
IN
+
–
Power Supply Voltage ........................................... 5.5V
Enable Voltage ................................... –0.2V, V
CC
+ 0.2V
Input Power (Note 2) ......................................... 22dBm
Operating Ambient Temperature Range .. – 40°C to 85°C
Storage Temperature Range ................ – 65°C to 125°C
Maximum Junction Temperature ......................... 125°C
8
9
7
6
5
OUT
V
EE
V
CC
CAP
–
2
3
CAP
+
4
DDB PACKAGE
8-LEAD (3mm
´
2mm) PLASTIC DFN
θ
JA
= 76°C/W
EXPOSED PAD (PIN 9) SHOULD BE SOLDERED TO PCB
ORDER PART NUMBER
LT5537EDDB
DDB PART MARKING
LBJR
Order Options
Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking:
http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
PARAMETER
Signal Input
Input Frequency Range
Maximum Input Power for Monotonic Output
(Note 5)
V
CC
= 3V, ENBL = 3V, T
A
= 25°C, unless otherwise specified. (Notes 3, 4)
MIN
TYP
10 to 1000
14.0
11.6
9.4
V
CC
– 0.4
1.73kΩ //1.45pF
88.8
72.5
19.6
–97
–76.7
–0.007
90.6
81.0
20
–96
–77.2
–0.005
dB
dB
mV/dB
dBm
dBm
dB/°C
dB
dB
mV/dB
dBm
dBm
dB/°C
MAX
UNITS
MHz
dBm
dBm
dBm
V
CONDITIONS
50Ω Termination
200MHz
600MHz
1GHz
Measured at 200MHz
±3dB
Error
±1dB
Error
R1 = 33k (Note 8)
V
OUT
= 0V, Extrapolated
(Notes 3, 7)
P
IN
= –20dBm
±3dB
Error
±1dB
Error
R1 = 33k (Note 8)
V
OUT
= 0V, Extrapolated
(Notes 3, 7)
P
IN
= –20dBm
DC Common Mode Voltage
Small-Signal Impedance
f = 10MHz
Linear Dynamic Range
Slope
Intercept
Sensitivity
Temperature Coefficient
f = 50MHz
Linear Dynamic Range
Slope
Intercept
Sensitivity
Temperature Coefficient
2
U
5537fa
W
U
U
W W
W
LT5537
ELECTRICAL CHARACTERISTICS
PARAMETER
f = 100MHz
Linear Dynamic Range
Slope
Intercept
Sensitivity
Temperature Coefficient
f = 200MHz
Linear Dynamic Range
Slope
Intercept
Sensitivity
Temperature Coefficient
f = 400MHz
Linear Dynamic Range
Slope
Intercept
Sensitivity
Temperature Coefficient
f = 600MHz
Linear Dynamic Range
Slope
Intercept
Sensitivity
Temperature Coefficient
f = 1GHz
Linear Dynamic Range
Slope
Intercept
Sensitivity
Temperature Coefficient
Output
Starting Voltage
Response Time
Baseband Modulation Bandwidth
Shutdown Mode
ENBL = High (On)
ENBL = Low (Off)
ENBL Input Current
Turn-On Time
Turn-Off Time
V
ENBL
= 3V
V
ENBL
= 0V
±3dB
Error
±1dB
Error
±3dB
Error
±1dB
Error
±3dB
Error
±1dB
Error
±3dB
Error
±1dB
Error
±3dB
Error
±1dB
Error
V
CC
= 3V, ENBL = 3V, T
A
= 25°C, unless otherwise specified. (Notes 3, 4)
MIN
TYP
90.5
82.8
20.3
–95
–77
–0.004
90.3
83.5
21.2
–94
–76.4
0.010
88.2
70.8
23.1
–91
–75.3
0.019
85.8
72.5
25.2
–89
–74.1
0.026
63.5
51.7
31.4
–80
–69.2
0.031
0.4
110
6
1
0.3
100
0
100
100
MAX
UNITS
dB
dB
mV/dB
dBm
dBm
dB/°C
dB
dB
mV/dB
dBm
dBm
dB/°C
dB
dB
mV/dB
dBm
dBm
dB/°C
dB
dB
mV/dB
dBm
dBm
dB/°C
dB
dB
mV/dB
dBm
dBm
dB/°C
V
ns
MHz
V
V
µA
µA
µs
µs
5537fa
CONDITIONS
R1 = 33k (Note 8)
V
OUT
= 0V, Extrapolated
(Notes 3, 7)
P
IN
= –20dBm
R1 = 33k (Note 8)
V
OUT
= 0V, Extrapolated
(Notes 3, 7)
P
IN
= –20dBm
R1 = 33k (Note 8)
V
OUT
= 0V, Extrapolated
(Notes 3, 7)
P
IN
= –20dBm
R1 = 33k (Note 8)
V
OUT
= 0V, Extrapolated
(Notes 3, 7)
P
IN
= –20dBm
R1 = 33k (Note 8)
V
OUT
= 0V, Extrapolated
(Notes 3, 7)
P
IN
= –20dBm
No RF Signal Present
Input from –30dBm to 0dBm, C
LOAD
= 2.5pF
Output Load Capacitance = 2.5pF
3
LT5537
ELECTRICAL CHARACTERISTICS
PARAMETER
Power Supply
Supply Voltage
Supply Current
Shutdown Current
(Note 6)
V
CC
= 3V
ENBL = Low
V
CC
= 3V, ENBL = 3V, T
A
= 25°C, unless otherwise specified. (Notes 3, 4)
MIN
2.7
10
13.5
500
TYP
MAX
5.25
15
UNITS
V
mA
µA
CONDITIONS
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
Maximum differential AC input voltage between IN
+
and IN
–
is 4V
peak. Equivalent to 22dBm with 50Ω input impedance or 16dBm with
200Ω input impedance (1:4 transformer used).
Note 3:
Tests are performed as shown in the configuration of Figure 13.
Note 4:
Specifications over the –40°C to 85°C temperature range are
assured by design, characterization and correlation with statistical process
control.
Note 5:
Operation at lower frequency is possible as described in the “Low
Frequency Operation” section in Applications Information.
Note 6:
The maximum output voltage is limited to approximately V
CC
–
0.6V. Either the output slope should be reduced or input power level
should be limited in order to avoid saturating the output circuit when V
CC
<
3V. See discussion in “Dynamic Range” section.
Note 7:
Sensitivity is defined as the minimum input power required for the
output voltage to be within 3dB of the ideal log-linear transfer curve.
Sensitivity can be improved by as much as 10dB by using a narrowband
input impedance transformation network. See discussion in “Input
Matching” section.
Note 8:
The output slope is adjustable using an external pull-down resistor
(R1). See Applications Information for description of the output circuit.
TYPICAL PERFOR A CE CHARACTERISTICS
Supply Current vs Supply Voltage
20
RF INPUT SIGNAL OFF
ENBL = V
CC
ENBL CURRENT (µA)
T
A
= 85°C
16
T
A
= 25°C
14
18
SUPPLY CURRENT (mA)
12
10
2.5
3.0
4
U W
ENBL Current vs Supply Voltage
250
RF INPUT SIGNAL OFF
ENBL = V
CC
200
T
A
= 85°C
150
T
A
= 25°C
T
A
= –40°C
100
T
A
= –40°C
50
3.5
4.0
4.5
SUPPLY VOLTAGE (V)
5.0
5.5
5537 G02
2.5
3.0
3.5
4.0
4.5
SUPPLY VOLTAGE (V)
5.0
5.5
5537 G03
5537fa
LT5537
TYPICAL PERFOR A CE CHARACTERISTICS
Output Voltage, Linearity Error
vs Input Power at 10MHz
2.4
2.0
25°C
1.6
V
OUT
(V)
–40°C
1.2
0.8
0.4
0
–80
85°C
0
–1
–2
–3
–60
–40
–20
0
INPUT POWER (dBm)
20
5537 G04
V
CC
= ENBL = 3V
V
OUT
VARIATION (dB)
0
–1
–2
–3
–80
85°C
V
OUT
(V)
V
OUT
Variation vs Input Power
at 50MHz
3
2
V
OUT
VARIATION (dB)
85°C
1
0
–1
–2
–3
–80
–40°C
V
OUT
(V)
1.6
1.2
0.8
0.4
NORMALIZED AT 25°C
V
CC
= ENBL = 3V
25°C
V
OUT
VARIATION (dB)
–60
–40
–20
0
INPUT POWER (dBm)
Output Voltage, Linearity Error
vs Input Power at 200MHz
2.4
2.0
85°C
1.6
V
OUT
(V)
25°C
–40°C
V
OUT
VARIATION (dB)
1.2
0.8
0.4
0
–1
–2
–3
20
5537 G10
0
–1
–40°C
–2
–3
–80
V
OUT
(V)
V
CC
= ENBL = 3V
0
–80
–60
–40
–20
0
INPUT POWER (dBm)
U W
20
5537 G07
V
OUT
Variation vs Input Power
at 10MHz
3
2
LINEARITY ERROR (dB)
LINEARITY ERROR (dB)
Output Voltage, Linearity Error
vs Input Power at 50MHz
2.4
2.0
85°C
1.6
1.2
0.8
0.4
0
–80
25°C
V
CC
= ENBL = 3V
3
2
LINEARITY ERROR (dB)
1
0
–1
–2
–3
–60
–40
–20
0
INPUT POWER (dBm)
20
5537 G06
3
2
1
NORMALIZED AT 25°C
V
CC
= ENBL = 3V
1
–40°C
–40°C
–60
–40
–20
0
INPUT POWER (dBm)
20
5537 G05
Output Voltage, Linearity Error
vs Input Power at 100MHz
2.4
2.0
85°C
1
0
–1
–2
–3
–60
–40
–20
0
INPUT POWER (dBm)
20
5537 G08
V
OUT
Variation vs Input Power
at 100MHz
3
2
V
CC
= ENBL = 3V
3
2
85°C
1
0
–1
–40°C
–2
–3
–80
LINEARITY ERROR (dB)
NORMALIZED AT 25°C
V
CC
= ENBL = 3V
–40°C
0
–80
–60
–40
–20
0
INPUT POWER (dBm)
20
5537 G09
V
OUT
Variation vs Input Power
at 200MHz
3
2
1
3
2
85°C
1
NORMALIZED AT 25°C
V
CC
= ENBL = 3V
Typical Detector Characteristics
2.4
2.0
1.6
1.2
0.8
0.4
0
–80
T
A
= 25°C
200MHz
ENBL = V
CC
5V
3V
–60
–40
–20
0
INPUT POWER (dBm)
20
5537 G11
–60
–20
–40
INPUT POWER (dBm)
0
20
5537 G12
5537fa
5
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