LT5538 - 40MHz to 3.8GHz RF Power Detector with 75dB Dynamic Range

LT5538
40MHz to 3.8GHz
RF Power Detector with
75dB Dynamic Range
FEATURES
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DESCRIPTION
The LT®5538 is a 40MHz to 3800MHz monolithic logarithmic RF power detector, capable of measuring RF signals
over a wide dynamic range, from –75dBm to 10dBm. The
RF signal in an equivalent decibel-scaled value is precisely
converted into DC voltage on a linear scale. The wide linear
dynamic range is achieved by measuring the RF signal using cascaded RF limiters and RF detectors. Their outputs
are summed to generate an accurate linear DC voltage
proportional to the input RF signal in dBm. The LT5538
delivers superior temperature stable output (within ±1dB
over full temperature range) from 40MHz to 3.8GHz. The
output is buffered with a low impedance driver.
Frequency Range: 40MHz to 3.8GHz
75dB Log Linear Dynamic Range
Exceptional Accuracy over Temperature
Linear DC Output vs. Input Power in dBm
–72dBm Detection Sensitivity
Single-ended RF Input
Low Supply Current: 29mA
Supply Voltage: 3V to 5.25V
8-lead DFN 3mm × 3mm package
APPLICATIONS
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Received Signal Strength Indication (RSSI)
RF Power Measurement and Control
RF/IF Power Detection
Receiver RF/IF Gain Control
Envelope Detection
ASK Receiver
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
Output Voltage and Linearity Error
vs Input Power
40MHz - 3.8GHz Logarithmic RF Detector
2.0
1nF
1nF
OUT
CAP+
IN–
CAP–
GND
VCC
9
VOUT
5V
5538 TA01
0.1μF
100pF
3
VCC = 5V AT 880 MHz
1.7
2
1.4
1
1.1
0
0.8
–1
0.5
TA = –40°C
TA = 25°C
TA = 85°C
0.2
–75 –65 –55 –45 –35 –25 –15
INPUT POWER (dBm)
–5
LINEARITY ERROR (dB)
56
ENBL
IN+
VOUT (V)
EN
RF
INPUT
LT5538
–2
5
–3
5538 TA02
5538f
1
LT5538
ABSOLUTE MAXIMUM RATINGS
PIN CONFIGURATION
(Note 1)
TOP VIEW
Power Supply Voltage ..............................................5.5V
Enable Voltage .....................................–0.3V, VCC + 0.3V
RF Input Power ....................................................15dBm
Operating Ambient Temperature ............ –40°C to +85°C
Storage Temperature Range................. –65°C to +125°C
Maximum Junction Temperature........................... 150°C
ENBL 1
8
OUT
IN+ 2
7
CAP+
IN–
3
6
CAP–
GND 4
5
VCC
DD PACKAGE
8-LEAD (3mm × 3mm) PLASTIC DFN
θJA = 43°C/W
EXPOSED PAD (PIN 9) SHOULD BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LT5538IDD#PBF
LT5538IDD#TRPBF
LCVG
8-Lead (3mm × 3mm) Plastic DFN
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C, VCC = 5V, ENBL = 5V. (Note 2)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
RF Input
Input Frequency Range
40 to 3800
DC Common Mode Voltage
Input Resistance
MHz
VCC –0.5
V
394
Ω
fRF = 40 MHZ
RF Input Power Range
Linear Dynamic Range
–75 to 10
±1dB Linearity Error (Note 3)
76
Output Slope
Logarithmic Intercept
(Note 5)
Sensitivity
Output Variation vs Temperature
Normalized to Output at 25°C
PIN = –50dBm; –40°C < TA < 85°C
PIN = –30dBm; –40°C < TA < 85°C
PIN = –10dBm; –40°C < TA < 85°C
●
●
●
dBm
dB
19.9
mV/dB
–87.5
dBm
–72
dBm
0.1/0.6
–0.1/0.6
–0.2/0.6
dB
dB
dB
5538f
2
LT5538
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C, VCC = 5V, ENBL = 5V. (Note 2)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
2nd Order Harmonic Distortion
Pin = –10dBm; At RF Input
–62
dBc
3rd Order Harmonic Distortion
Pin = –10dBm; At RF Input
–61
dBc
–75 to 10
dBm
fRF = 450 MHz
RF Input Power Range
Linear Dynamic Range
±1 dB Linearity Error (Note 3)
75
Output Slope
Logarithmic Intercept
(Note 5)
Sensitivity
Output Variation vs Temperature
Normalized to Output at 25°C
PIN = –50dBm; –40°C < TA < 85°C
PIN = –30dBm; –40°C < TA < 85°C
PIN = –10dBm; –40°C < TA < 85°C
●
●
●
dB
19.6
mV/dB
–87.3
dBm
–71.5
dBm
0.1/0.6
0.1/0.5
–0.1/0.5
dB
dB
dB
2nd Order Harmonic Distortion
Pin = –10dBm; At RF Input
–43
dBc
3rd Order Harmonic Distortion
Pin = –10dBm; At RF Input
–44
dBc
–75 to 10
dBm
fRF = 880 MHz
RF Input Power Range
Linear Dynamic Range
±1 dB Linearity Error (Note 3)
75
Output Slope
Logarithmic Intercept
19.0
(Note 5)
Sensitivity
Output Variation vs Temperature
Normalized to Output at 25°C
PIN = –50dBm; –40°C < TA < 85°C
PIN = –30dBm; –40°C < TA < 85°C
PIN = –10dBm; –40°C < TA < 85°C
●
●
●
dB
mV/dB
–88.8
dBm
–71.5
dBm
0.1/0.7
0.1/0.4
0.1/0.4
dB
dB
dB
2nd Order Harmonic Distortion
Pin = –10dBm; At RF Input
–37
dBc
3rd Order Harmonic Distortion
Pin = –10dBm; At RF Input
–40
dBc
–72 to 10
dBm
fRF = 2140 MHz
RF Input Power Range
Linear Dynamic Range
±1 dB Linearity Error (Note 3)
70
Output Slope
Logarithmic Intercept
17.7
(Note 5)
Sensitivity
Output Variation vs Temperature
Normalized to Output at 25°C
PIN = –50dBm; –40°C < TA < 85°C
PIN = –30dBm; –40°C < TA < 85°C
PIN = –10dBm; –40°C < TA < 85°C
●
●
●
dB
mV/dB
–89.0
dBm
–69.0
dBm
0.3/0.4
0.4/0.1
0.7/0.5
dB
dB
dB
fRF = 2700 MHz
RF Input Power Range
Linear Dynamic Range
–72 to 10
±1 dB Linearity Error (Note 3)
Output Slope
Logarithmic Intercept
(Note 5)
65
dBm
dB
17.6
mV/dB
–87.5
dBm
5538f
3
LT5538
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C, VCC = 5V, ENBL = 5V. (Note 2)
SYMBOL
PARAMETER
CONDITIONS
MIN
Sensitivity
Output Variation vs Temperature
TYP
MAX
–69.5
Normalized to Output at 25°C
PIN = –50dBm; –40°C < TA < 85°C
PIN = –30dBm; –40°C < TA < 85°C
PIN = –10dBm; –40°C < TA < 85°C
●
●
●
UNITS
dBm
0.3/0.3
0.7/–0.3
1.1/–0.9
dB
dB
dB
–65 to 10
dBm
fRF = 3600 MHz
RF Input Power Range
Linear Dynamic Range
±1 dB Linearity Error (Note 3)
Output Slope
Logarithmic Intercept
(Note 5)
Sensitivity
Output Variation vs Temperature
Normalized to Output at 25°C
PIN = –45dBm; –40°C < TA < 85°C
PIN = –25dBm; –40°C < TA < 85°C
PIN = –5dBm; –40°C < TA < 85°C
●
●
●
57
dB
18
mV/dB
–81.4
dBm
–63
dBm
0.6/–0.3
0.9/–0.6
1.4/–1.2
dB
dB
dB
0.350
V
Output Impedance
150
Ω
Source Current
10
mA
Output Interface
Output DC Voltage
No RF Signal Present
Sink Current
200
μA
Rise Time
0.5V to 1.6V, 10% to 90%, fRF = 880 MHz
100
ns
Fall Time
1.6V to 0.5V, 10% to 90%, fRF = 880 MHz
180
ns
Power Up/Down
ENBL = High (On)
●
ENBL = Low (Off)
●
ENBL Input Current
1
V
0.3
VENBL = 5V
V
205
μA
Turn ON time
300
ns
Turn OFF Time
1
μs
Power Supply
Supply Voltage
3
Supply Current
Shutdown Current
ENBL = Low
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: Specifications over the –40°C to 85°C temperature range are
assured by design, characterization and correlation with statistical process
control.
Note 3: The linearity error is calculated by the difference between the
incremental slope of the output and the average slope from –50dBm
5.25
V
29
36
mA
1
100
μA
to –20dBm. The dynamic range is defined as the range over which the
linearity error is within ±1dB.
Note 4: Sensitivity is defined as the minimum input power required for the
linearity error within 3dB of the ideal log-linear transfer curve.
Note 5: Logarithmic Intercept is an extrapolated input power level from the
best-fitted log-linear straight line, where the output voltage is 0V.
5538f
4
LT5538
TYPICAL PERFORMANCE CHARACTERISTICS
2
2
30
1.4
1
1.1
0
0.8
–1
25
20
0.5
TA = –40°C
TA = 25°C
TA = 85°C
2.5
3
5
3.5
4
4.5
SUPPLY VOLTAGE VCC (V)
0.2
–75 –65 –55 –45 –35 –25 –15
INPUT POWER (dBm)
5.5
–5
3
1.1
0
0.8
–1
0.2
–75 –65 –55 –45 –35 –25 –15
INPUT POWER (dBm)
–5
5538 G03
Output Voltage, Linearity Error vs
Input Power at 880MHz
2.0
1
1.4
1
1.1
0
0.8
–1
0
–1
–5
0.2
–75 –65 –55 –45 –35 –25 –15 –5
INPUT POWER (dBm)
5
5538 G05
3
3
2
1
1.4
1
1.1
0
0.8
–1
VOUT (V)
2
–3
–75 –65 –55 –45 –35 –25 –15
INPUT POWER (dBm)
–5
5
5538 G07
TA = –40°C
TA = 25°C
TA = 85°C
0.2
–75 –65 –55 –45 –35 –25 –15
INPUT POWER (dBm)
–5
–2
5
5538 G08
–3
LINEARITY ERROR (dB)
1.7
0.5
–3
5
VOUT Variation vs Input Power at
2.14GHz
Output Voltage, Linearity Error vs
Input Power at 2.14GHz
VCC = 5V
–2
5538 G06
2
TA = –40°C
TA = 85°C
TA = –40°C
TA = 25°C
TA = 85°C
0.5
–3
–75 –65 –55 –45 –35 –25 –15
INPUT POWER (dBm)
2.0
–2
3
VCC = 5V
2
TA = –40°C
TA = 85°C
–3
5
1.7
VCC = 5V
NORMALIZED AT 25°C
–1
–5
2
VOUT Variation vs Input Power at
880MHz
0
–3
–75 –65 –55 –45 –35 –25 –15
INPUT POWER (dBm)
VCC = 5V
NORMALIZED AT 25°C
5538 G04
3
TA = –40°C
TA = 85°C
–3
–2
–2
5
–1
–2
VOUT (V)
1
TA = –40°C
TA = 25°C
TA = 85°C
0
LINEARITY ERROR (dB)
1.4
LINEARITY ERROR (dB)
2
VOUT VARIATION (dB)
3
1.7
0.5
1
VOUT Variation vs Input Power at
450MHz
Output Voltage, Linearity Error vs
Input Power at 450MHz
VCC = 5V
5
VCC = 5V
NORMALIZED AT 25°C
5538 G02
5538 G01
2.0
–2
TA = –40°C
TA = 25°C
TA = 85°C
VOUT VARIATION (dB)
10
VCC = 5V
VOUT VARIATION (dB)
35
1.7
VOUT (V)
SUPPLY CURRENT ICC (mA)
3
2.0
LINEARITY ERROR (dB)
3
40
15
VOUT (V)
VOUT Variation vs Input Power at
40MHz
Output Voltage, Linearity Error vs
Input Power at 40MHz
Supply Current vs Supply Voltage
VOUT VARIATION (dB)
(Test Circuit shown in Figure 5)
VCC = 5V
NORMALIZED AT 25°C
1
0
–1
–2
TA = –40°C
TA = 85°C
–3
–75 –65 –55 –45 –35 –25 –15 –5
INPUT POWER (dBm)
5
5538 G09
5538f
5
LT5538
TYPICAL PERFORMANCE CHARACTERISTICS
Output Voltage, Linearity Error vs
Input Power at 2.7GHz
VOUT Variation vs Input Power at
2.7GHz
1.2
1
0.9
0
0.6
–1
–2
0
–70 –60 –50 –40 –30 –20 –10
INPUT POWER (dBm)
2
1
1.2
1
0.9
0
0.6
–1
0
–1
TA = –40°C
TA = 85°C
–3
–70 –60 –50 –40 –30 –20 –10
INPUT POWER (dBm)
0
5538 G10
40
PERCENTAGE DISTRIBUTION (%)
VOUT VARIATION (dB)
2
1
0
–1
–2
30
25
20
15
10
0
0
10
12
10
8
6
4
16
16.8 17.6 18.4 19.2
SLOPE (mV/dB)
20
0
–98 –96 –94 –92 –90 –88 –86 –84 –82 –80 –78
LOGARITHMIC INTERCEPT (dBm)
20.8
5538 G15
5538 G14
Output Voltage, Linearity Error vs
VCC @3600MHz
Output Voltage, Linearity Error vs
VCC @2140MHz
Output Voltage, Linearity Error vs
VCC @40MHz
2.0
TA = –40°C
TA = 25°C
TA = 85°C
14
2
5538 G13
3
2.0
NORMALIZED AT 5V
1.8
3
1
1.1
0
0.8
–1
–2
0.5
VCC = 5V
VCC = 3V
–5
5
5538 G16
–3
VOUT (V)
1.4
1.7
2
1.4
1
1.1
0
0.8
–1
0.5
–2
VCC = 5V
VCC = 3V
0.2
–75 –65 –55 –45 –35 –25 –15
INPUT POWER (dBm)
–5
5
5538 G17
–3
1.5
2
1.2
1
0.9
0
0.6
–1
0.3
0
–65
LINEARITY ERROR (dB)
2
LINEARITY ERROR (dB)
1.7
3
VCC = 5V
NORMALIZED AT 5V
LINEARITY ERROR (dB)
VOUT (V)
16
TA = –40°C
TA = 25°C
TA = 85°C
35
–3
5
Logarithmic Intercept Distribution
vs Temperature at 2.14GHz
5
TA = –40°C
TA = 85°C
–3
–70 –60 –50 –40 –30 –20 –10
INPUT POWER (dBm)
–45 –35 –25 –15 –5
INPUT POWER (dBm)
–2
5538 G12
Slope Distribution vs
Temperature at 2.14GHz
VCC = 5V
NORMALIZED AT 25°C
0.2
–75 –65 –55 –45 –35 –25 –15
INPUT POWER (dBm)
0
–65 –55
10
5538 G11
VOUT Variation vs Input Power at
3.6GHz
3
TA = –40°C
TA = 25°C
TA = 85°C
0.3
–2
–3
10
0
1.5
PERCENTAGE DISTRIBUTION (%)
TA = –40°C
TA = 25°C
TA = 85°C
3
VCC = 5V
2
VOUT (V)
0.3
VOUT VARIATION (dB)
2
1.8
VCC = 5V
NORMALIZED AT 25°C
LINEARITY ERROR (dB)
1.5
3
Output Voltage, Linearity Error vs
Input Power at 3.6GHz
VOUT (V)
3
VCC = 5V
LINEARITY ERROR (dB)
VOUT (V)
1.8
(Test Circuit shown in Figure 5)
–2
VCC = 5V
VCC = 3V
–55 –45 –35 –25 –15 –5
INPUT POWER (dBm)
–3
5
5538 G18
5538f
6
LT5538
PIN FUNCTIONS
ENBL (Pin 1): Enable Pin. An applied voltage above 1V will
activate the bias for the IC. For an applied voltage below
0.3V, the circuits will be shut down (disabled) with a corresponding reduction in power supply current. If the enable
function is not required, then this pin can be connected
to VCC. Typical enable pin input currents are 100μA for
EN = 3V and 200μA for EN = 5V, respectively. Note that at
no time should the ENBL pin voltage be allowed to exceed
VCC by more than 0.3V.
This pin should be connected to ground with an external
ac-decoupling capacitor for low frequency operation.
GND (Pin 4, Exposed Pad Pin 9): Circuit Ground Return
for the entire IC. This pin must be soldered to the printed
circuit board ground plane.
VCC (Pin 5): Power Supply Pin. This pin should be decoupled using 100pF and 0.1μF capacitors.
CAP–, CAP+ (Pins 6, 7): Optional Filter Capacitor Pins.
These pins are internally connected to the detector outputs
in front of the output buffer amplifier. An external low-pass
filtering can be formed by connecting a capacitor to Vcc
from each pin for filtering a low frequency modulation signal. See the Applications Information section for detail.
IN+ (Pin 2): RF Input Pin. The pin is internally biased to
VCC –0.5V and should be DC blocked externally. The input
is connected via internal 394Ω resistor to the IN– pin which
should be connected to ground with an ac-decoupling
capacitor.
IN– (Pin 3): AC Ground Pin. The pin is internally biased to
VCC –0.5V and coupled to ground via internal 20pF capacitor.
OUT (Pin 8): Detector DC Output Pin.
BLOCK DIAGRAM
5 VCC
DC OFFSET CANCELLATION
1 ENBL
IN+ 2
RF LIMITER
IN–
RF LIMITER
RF LIMITER
RF LIMITER
RF LIMITER
3
8 OUT
RF DETECTOR CELLS
4
9
GND
6
7
5538 BD01
CAP– CAP+
5538f
7
LT5538
APPLICATIONS INFORMATION
The LT5538 is a 40MHz to 3.8 GHz logarithmic RF power
detector. It consists of cascaded limiting amplifiers and
RF detectors. The output currents from every RF detector
are combined and low-pass filtered before applied to the
output buffer amplifier. As a result, the final DC output
voltage approximates the logarithm of the amplitude of the
input signal. The LT5538 is able to accurately measure an
RF signal over a 70dB dynamic range (–68dBm to 2dBm
at 2.1GHz) with 50Ω single-ended input impedance. The
slope of linear to log transfer function is about 17.7mV/dB
at 2.1GHz. Within the linear dynamic range, very stable
output is achieved over the full temperature range from
–40°C to 85°C and over the full operating frequency
range from 40MHz to 3.8GHz. The absolute variation over
temperature is typically within ±1dB over 65dB dynamic
range at 2.1GHz.
RF INPUT
The simplified schematic of the input circuit is shown in
Figure 1. The IN+ and IN– pins are internally biased to
VCC –0.5V. The IN– pin is internally coupled to ground via
20pF capacitor. An external capacitor of 1nF is needed to
connect this pin to ground for low frequency operation.
The impedance between IN+ and IN– is about 394Ω. The
RF input pin IN+ should be DC blocked when connected
to ground or other matching components. A 56Ω resistor
(R1) connected to ground will provide better than 10dB
input return loss over the operating frequency range up
to 1.5GHz. At higher operating frequency, additional LC
matching elements are needed for a proper impedance
matching to a 50Ω source as shown in Figure 2. Refer to
Figure 6 for the circuit schematic of the input matching
network. The input impedance vs frequency of the RF input
port IN+ is detailed in Table 1.
Table 1. RF Input Impedance
FREQUENCY
(MHz)
RF INPUT
IMPEDANCE (Ω)
MAG
ANGLE(°)
40
47.3 + j129.7
0.800
38.5
100
246.6 + j210.7
0.790
11.5
200
408.7 – j37.8
0.785
–1.5
400
192.9 – j190.9
0.772
–14.9
600
105.6 – j158.4
0.756
–25.3
800
69.3 – j127.4
0.737
–34.4
1000
51.8 – j106.2
0.720
–42.7
1200
41.5 – j90.9
0.707
–50.6
1400
34.2 – j78.7
0.697
–58.2
1600
29.2 – j60.0
0.687
–65.6
1800
25.4 – j60.7
0.678
–73.1
2000
22.6 – j53.8
0.669
–80.4
2200
20.5 – j47.7
0.659
–87.7
2400
18.9 – j42.4
0.649
–94.6
2600
17.9 – j37.6
0.638
–101.5
2800
17.1 – j33.4
0.627
–108.2
3000
16.4 – j29.5
0.615
–114.7
3200
16.1 – j26.0
0.602
–121.0
3400
15.9 – j22.8
0.589
–127.0
3600
15.9 – j20.0
0.574
–132.8
3800
15.9 – j17.5
0.560
–137.9
0
VCC
–5
5.3k
INPUT RETURN LOSS (dB)
5.3k
S11
IN+
394
IN–
20p
+
–
5538 F01
–10
–15
–20
–25
–30
W/O L1 AND C8
L1 = 1.5nH, C8 = 1pF
C4, C11 = 12pF, C8 = 0.7pF
0 0.4 0.8 1.2 1.6 2 2.4 2.8 3.2 3.6 4.0
FREQUENCY (GHz)
5538 F02
Figure 1. Simplified Schematic of the Input Circuit
Figure 2. Input Return Loss with Additional LC Matching Network
5538f
8
LT5538
APPLICATIONS INFORMATION
OUTPUT INTERFACE
The output interface of the LT5538 is shown in Figure 3.
This output buffer circuit can source 10mA current to the
load and sink 200 μA current from the load. The smallsignal output bandwidth is approximately 4MHz when the
output is resistively terminated or open. The full-scaled
10% to 90% rise and fall times are 100nS and 180nS,
respectively. The output transient responses at varied
input power levels are shown in Figure 4.
VCC
200
C6
200
100μA
20p
+
–
C9
OUT
CAP+
+
–
CAP–
OUTPUT CURRENTS
FROM RF DETECTORS
150
200μA
+
–
LT5538
5538 F03
Figure 3. Simplified Schematic of the Output Interface
3.0
2.5
VOUT (V)
1.5
1.0
RF PULSE ON
RF PULSE OFF
EXTERNAL FILTERING AT CAP+, CAP–
The CAP+ and CAP– Pins are internally biased at VCC –0.36V
via a 200Ω resistor from voltage supply VCC as shown in
Figure 3. These two pins are connected to the differential
outputs of the internal RF detector cells. In combination
with the 20pF in parallel, a low-pass filter is formed with
–3dB corner frequency of 20MHz. The high frequency
rectified signals (particularly second-order harmonic of
the RF signal) from the detector cells are filtered and then
the DC output is amplified by the output buffer amplifier. In
some applications, the LT5538 may be used to measure a
modulated RF signal with low frequency AM content (lower
than 20MHz), a large modulation signal may be present
at these two pins due to insufficient low-pass filtering,
resulting in output voltage fluctuation at the LT5538’s
output. Its DC content may also vary depending upon the
modulation frequency. To assure stable DC output of the
LT5538, external capacitors C6 and C9 can be connected
from CAP+ and CAP– to VCC to filter out this low frequency
AM modulation signal. Assume the modulation frequency
of the RF signal is fMOD, the capacitor value in Farads of
C6 and C9 can be chosen by the following formula:
6
2
RF PULSE OFF
–2
PIN = 0dBm
PIN = 10dBm
PIN = 20dBm –6
PIN = 30dBm
PIN = 40dBm
–10
PIN = 50dBm
0.5
–14
0
–18
0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
TIME (μs)
RF PULSE ENABLE (V)
2.0
AT 880MHZ
When the part is enabled, the output impedance is about
150Ω. When it is disabled, the output impedance is about
29.5kΩ referenced to ground.
C6 (or C9) ≥ 10/(2π • 200 • fMOD)
Do not connect these two filtering capacitors to ground
or any other low voltage reference at any time to avoid an
abnormal start-up condition.
5538 F04
Figure 4. Simplified Circuit Schematic of the Output Interface
5538f
9
LT5538
APPLICATIONS INFORMATION
μA. To disable or turn off the chip, this voltage should be
below 0.3V. It is important that the voltage applied to the
ENBL pin should never exceed VCC by more than 0.3V.
Otherwise, the supply current may be sourced through the
upper ESD protection diode connected at the ENBL pin.
Under no circumstances should voltage be applied to the
ENBL Pin before the supply voltage is applied to the VCC
pin. If this occurs, damage to the IC may result.
ENBL (ENABLE) PIN OPERATION
A simplified circuit schematic of the ENBL Pin is shown
in Figure 5. The enable voltage necessary to turn on the
LT5538 is 1V. The current drawn by the ENBL pin varies
with the voltage applied at the pin. When the ENBL voltage is 3V, the ENBL current is typically 100 μA. When the
ENBL voltage is 5V, the ENBL current is increased to 200
VCC
ENBL
42k
42k
5538 F05
Figure 5. Simplified Schematic of the Enable Circuit
TEST CIRCUIT
ENABLE
R4
4.99k
L1
RF
INPUT
1.5nH
C8
1pF
R1
56Ω
1
C4
1nF
C5
1nF
LT5538
ENBL
OUT
8
R5
O
2
IN+
CAP+
7
3
IN–
CAP–
6
4
GND
VCC
9
5
C9
OPT
5538 TC01
C2
100pF
C1
0.1μF
C7
OPT
VOUT
C6
OPT
C10
100pF
5V
Figure 6. Evaluation Board Circuit Schematic
40MHz to 2.7GHz
3.6GHz to 3.8GHz
REF DES
VALUE
SIZE
PART NUMBER
REF DES
C1
0.1μF
0603
AVX 0603ZC104KAT
C4, C11
12pF
0402
MURATA, GRM155C1H120JZ01B
C2, C10
100pF
0402
AVX 0402YC101KAT
C8
0.7pF
0402
MURATA, GJR155C1HR70BB01
C5
OPEN
C4, C5
1nF
0603
AVX 0402ZC102K
C8
1pF
0402
AVX 0402YA1ROCAT
R1
56
0402
VISHAY, CRCW040256ROFKED
R4
4.99k
0402
VISHAY, CRCW04024K99FKED
L1
1.5nH
0402
TOKO, LL1005-FH2IN5S
VALUE
SIZE
PART NUMBER
NOTE: Replace L1 with C11.
5538f
10
LT5538
TEST CIRCUIT
5538 TC02
Figure 7. Component Side of Evalution Board
PACKAGE DESCRIPTION
DD Package
8-Lead Plastic DFN (3mm × 3mm)
(Reference LTC DWG # 05-08-1698)
R = 0.115
TYP
5
0.38 ± 0.10
8
0.675 ±0.05
3.5 ±0.05
1.65 ±0.05
2.15 ±0.05 (2 SIDES)
3.00 ±0.10
(4 SIDES)
PACKAGE
OUTLINE
1.65 ± 0.10
(2 SIDES)
PIN 1
TOP MARK
(NOTE 6)
(DD8) DFN 1203
0.200 REF
0.25 ± 0.05
0.50
BSC
2.38 ±0.05
(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
0.75 ±0.05
0.00 – 0.05
4
0.25 ± 0.05
1
0.50 BSC
2.38 ±0.10
(2 SIDES)
BOTTOM VIEW—EXPOSED PAD
NOTE:
1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-1)
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION
ON TOP AND BOTTOM OF PACKAGE
5538f
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
11
LT5538
RELATED PARTS
PART NUMBER DESCRIPTION
COMMENTS
Infrastructure
LT5514
Ultralow Distortion, IF Amplifier/ADC Driver with Digitally
Controlled Gain
850MHz Bandwidth, 47 dBm OIP3 at 100MHz, 10.5dB to 33dB Gain Control
Range
LT5515
1.5GHz to 2.5GHz Direct Conversion Quadrature Demodulator 20dBm IIP3, Integrated LO Quadrature Generator
LT5516
0.8GHz to 1.5GHz Direct Conversion Quadrature Demodulator 21.5dBm IIP3, Integrated LO Quadrature Generator
LT5517
40MHz to 900MHz Quadrature Demodulator
21dBm IIP3, Integrated LO Quadrature Generator
LT5518
1.5GHz to 2.4GHz High Linearity Direct Quadrature
Modulator
22.8dBm OIP3 at 2GHz, –158.2dBm/Hz Noise Floor, 50Ω Single-Ended RF
and LO Ports, 4-Channel W-CDMA ACPR = –64dBc at 2.14GHz
LT5519
0.7GHz to 1.4GHz High Linearity Upconverting Mixer
17.1dBm IIP3 at 1GHz, Integrated RF Output Transformer with 50Ω
Matching, Single-Ended LO and RF Ports Operation
LT5520
1.3GHz to 2.3GHz High Linearity Upconverting Mixer
15.9dBm IIP3 at 1.9GHz, Integrated RF Output Transformer with 50Ω
Matching, Single-Ended LO and RF Ports Operation
LT5521
10MHz to 3700MHz High Linearity Upconverting Mixer
24.2dBm IIP3 at 1.95GHz, NF = 12.5dB, 3.15V to 5.25V Supply, SingleEnded LO Port Operation
LT5522
600 MHz to 2.7GHz High Signal Level Downconverting
Mixer
4.5V to 5.25V Supply, 25dBm IIP3 at 900MHz, NF = 12.5dB, 50Ω SingleEnded RF and LO Ports
LT5524
Low Power, Low Distortion ADC Driver with Digitally
Programmable Gain
450MHz Bandwidth, 40dBm OIP3, 4.5dB to 27dB Gain Control
LT5525
High Linearity, Low Power Downconverting Mixer
Single-Ended 50Ω RF and LO Ports, 17.6dBm IIP3 at 1900MHz, ICC = 28mA
LT5526
High Linearity, Low Power Downconverting Mixer
3V to 5.3V Supply, 16.5dBm IIP3, 100kHz to 2GHz RF, NF = 11dB,
ICC = 28mA, –65dBm LO-RF Leakage
LT5527
400MHz to 3.7GHz High Signal Level Downconverting
Mixer
IIP3 = 23.5dBm and NF = 12.5dBm at 1900MHz, 4.5V to 5.25V Supply,
ICC = 78mA, Conversion Gain = 2dB
LT5528
1.5GHz to 2.4GHz High Linearity Direct Quadrature
Modulator
21.8dBm OIP3 at 2GHz, –159.3dBm/Hz Noise Floor, 50Ω, 0.5VDC Baseband
Interface, 4-Channel W-CDMA ACPR = –66dBc at 2.14GHz
LT5557
400MHz to 3.8GHz, 3.3V High Signal Level
Downconverting Mixer
IIP3 = 23.7dBm at 2600MHz, 23.5dBm at 3600MHz, ICC = 82mA at 3.3V
LT5560
Ultra-Low Power Active Mixer
10mA Supply Current, 10dBm IIP3, 10dB NF, Usable as Up- or Down-Converter.
LT5568
700MHz to 1050MHz High Linearity Direct Quadrature
Modulator
22.9dBm OIP3 at 850MHz, –160.3dBm/Hz Noise Floor, 50Ω, 0.5VDC
Baseband Interface, 3-Ch CDMA2000 ACPR = –71.4dBc at 850MHz
LT5572
1.5GHz to 2.5GHz High Linearity Direct Quadrature
Modulator
21.6dBm OIP3 at 2GHz, –158.6dBm/Hz Noise Floor, High-Ohmic 0.5VDC
Baseband Interface, 4-Ch W-CDMA ACPR = –67.7dBc at 2.14GHz
LT5575
800MHz to 2.7GHz High Linearity Direct Conversion I/Q
Demodulator
50Ω, Single-Ended RF and LO Inputs. 28dBm IIP3 at 900MHz, 13.2dBm
P1dB, 0.04dB I/Q Gain Mismatch, 0.4° I/Q Phase Mismatch
RF Power Detectors
LTC®5505
RF Power Detectors with >40dB Dynamic Range
300MHz to 3GHz, Temperature Compensated, 2.7V to 6V Supply
LTC5507
100kHz to 1000MHz RF Power Detector
100kHz to 1GHz, Temperature Compensated, 2.7 to 6V Supply
LTC5508
300MHz to 7GHz RF Power Detector
44dB Dynamic Range, Temperature Compensated, SC70 Package
LTC5509
300MHz to 3GHz RF Power Detector
36dB Dynamic Range, Low Power Consumption, SC70 Package
LTC5530
300MHz to 7GHz Precision RF Power Detector
Precision VOUT Offset Control, Shutdown, Adjustable Gain
LTC5531
300MHz to 7GHz Precision RF Power Detector
Precision VOUT Offset Control, Shutdown, Adjustable Offset
LTC5532
300MHz to 7GHz Precision RF Power Detector
Precision VOUT Offset Control, Adjustable Gain and Offset
LT5534
50MHz to 3GHz Log RF Power Detector with 60dB
Dynamic Range
±1dB Output Variation over Temperature, 38ns Response Time, Log Linear
Response
LTC5536
Precision 600Mhz to 7GHz RF Power Detector with Fast
Comparator Output
25ns Response Time, Comparator Reference Input, Latch Enable Input,
–26dBm to +12dBm Input Range
LT5537
Wide Dynamic Range Log RF/IF Detector
Low Frequency to 1GHz, 83dB Log Linear Dynamic Range
LT5570
2.7GHz RMS Power Detector
Fast Responding, up to 60dB Dynamic Range, ±0.3dB Accuracy Over
Temperature and Dynamic Range
5538f
12 Linear Technology Corporation
LT 0408 • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507 ● www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2008