DATA SHEET
SKY65050-372LF: 0.45-6.0 GHz Low Noise Transistor
Applications
• Wireless infrastructure: WLAN, WiMAX, broadband, cellular base
stations
• Test instrumentation
• LNA for GPS receivers
• Satellite receivers
Figure 1. SKY65050-372LF Block Diagram
Features
• Externally matched for wideband operation
• Noise Figure = 0.45 dB @ 2.4 GHz of device only
• Noise Figure = 0.65 dB @ 2.4 GHz including matching network
loss
• Gain = 15.5 dB @ 2.4 GHz
• OIP3 = +23.5 dBm @ 2.4 GHz, VDD = 3 V, IDD = 20 mA
• P1dB = +10.5 dBm @ 2.4 GHz, VDD = 3 V, IDD = 20 mA
• Adjustable supply current, 5 to 55 mA
• Small, SC-70 (4-pin, 2.20 x 1.35 x 1.10 mm) package (MSL1,
260 °C per JEDEC J-STD-020)
Description
The SKY65050-372LF is a high performance, n-channel low-noise
transistor. The device is fabricated from Skyworks advanced
depletion mode pHEMT process and is provided in a
2.20 x 1.35 x 1.10 mm, 4-pin SC-70 package.
The transistor’s low Noise Figure (NF), high gain, and excellent 3rd
Order Intercept Point (IP3) allow the device to be used in various
receiver and transmitter applications.
A functional block diagram is shown in Figure 1. The pin
configuration and package are shown in Figure 2. Signal pin
assignments and functional pin descriptions are provided in
Table 1.
Figure 2. SKY65050-372LF Pinout – 4-Pin SC-70
(Top View)
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DATA SHEET • SKY65050-372LF LOW NOISE TRANSISTOR
Table 1. SKY65050-372LF Signal Descriptions
Pin #
Name
Description
Pin #
Name
Description
1
SOURCE
Source lead. Provides DC self-biasing point
and AC ground.
3
SOURCE
Source lead. Provides DC self-biasing point
and AC ground.
2
DRAIN
RF output. Requires external matching
network for optimum performance. Supply
voltage required through external RF choke.
4
GATE
RF input. Requires external matching
network for optimum performance.
Table 2. Self-Biasing Resistors
Resistor Value (Ω)
Drain Current (mA)
130
5
47
10
27
15
20
20
15
25
10
30
Functional Description
The SKY65050-372LF is a depletion mode pHEMT designed for
low noise, high frequency applications. The SKY65050-372LF has
a typical NF of 0.65 dB tested at the 2.4 GHz wireless LAN
frequency band. A gain of 15.5 dB typical is achieved using the
same circuit. If the frequency of operation is lowered to the 1 GHz
range, NF performance of the device can approach 0.5 dB
including input matching network losses.
De-embedded scattering and noise parameters are provided in
addition to typical circuit topologies for commonly used frequency
bands. With an appropriate circuit, the SKY65050-372LF can be
used for many applications from 450 MHz up to 6 GHz. The
compact SC-70 package makes the SKY65050-372LF an ideal
low noise and low cost solution.
Biasing
To properly bias a depletion mode pHEMT, both the gate and drain
of the device must be properly biased. At VGS = 0 V and
VDS ≥ 2 V, the device is in a saturated state and draws the
maximum amount of current, IDSS. The device typically achieves
the best noise performance at VDS = 3 V and IDSS = 15 mA. To
control IDS, VGS must be biased with a negative voltage supply.
To eliminate the need for a negative DC supply, self-biasing
should be used when a resistor is placed between one of the
source leads and ground. A bypass capacitor should be placed in
parallel to this resistor to provide an RF ground and to ensure
performance remains unchanged at the operating frequency.
desired negative VGS value. This simplifies the design by
eliminating the need for a second DC supply.
Table 2 provides the resistor values used to properly bias the
SKY65050-372LF.
RF Matching Networks
The SKY65050-372LF Evaluation Board assembly diagram is
shown in Figure 12 and a circuit schematic is provided in
Figure 13. The schematic shows the recommended RF matching
network used for the 2.4 GHz wireless LAN frequency band. The
network was designed using de-embedded s- and n-parameters.
The circuit was primarily tuned for gain, NF, and input and output
return loss, while maintaining proper stability.
Optimal noise performance is attained when the impedance
presented to the input of the amplifier is equal to its minimum NF
impedance point. Components C1, C2, C3, L1, and L2 shown in
Figures 12 and 13 provide the necessary impedance match for NF
and input return loss. Circuit board and input matching structure
losses on the input of the amplifier directly add to the overall NF of
the amplifier. It is critical to minimize RF trace lengths and to use
high-Q components to achieve optimal NF performance.
Components R2 and C14 provide self biasing for the device and
RF grounding for one of the two source leads. Components C5 and
L3 are placed on the opposing source lead and are used to tune
the transistor’s source inductance.
When current flows from drain to source and through the resistor,
the source voltage becomes biased above DC ground. The gate
pin of the device should be left unbiased at 0 V, which creates the
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DATA SHEET • SKY65050-372LF LOW NOISE TRANSISTOR
Electrical and Mechanical Specifications
The effect of source inductance varies with frequency. Too little
source inductance increases gain and high frequency stability, but
at the cost of decreased in-band stability. Too much source
inductance decreases high frequency stability and gain, but
increases in-band stability. It is very important to find the optimum
tuning of source inductance that balances all of these variables.
The absolute maximum ratings of the SKY65050-372LF are
provided in Table 3. The recommended operating conditions are
specified in Table 4 and electrical specifications are provided in
Table 5.
Performance characteristics for the SKY65050-372LF are
illustrated in Figures 3 through 11.
The output matching topology is typical for an RF transistor.
Component L3 is the RF choke that prevents RF signals from
reaching the DC supply. Component C4 is the DC blocking
capacitor. Components C10 and C11 improve output return loss
and 3rd Order Output Intercept Point (OIP3) performance.
Table 3. SKY65050-372LF Absolute Maximum Ratings
Parameter
Symbol
Minimum
Typical
Maximum
Units
+10
dBm
+20
dBm
Input power
PIN
Output power
POUT
Drain source voltage
VDS
6.0
V
Gate to source voltage
VGS
–5.0
V
Gate to drain voltage
VGD
–5.0
V
Drain current
IDS
55
mA
Gate current
IGS
100
μA
Power dissipation
PDIS
240
mW
Channel temperature
TCHAN
150
°C
Storage temperature
TSTG
–65
+125
°C
Operating temperature
TOP
–40
+85
°C
Note:
Exposure to maximum rating conditions for extended periods may reduce device reliability. There is no damage to device with only one parameter set at the limit and all other
parameters set at or below their nominal value. Exceeding any of the limits listed here may result in permanent damage to the device.
Attention: Observe Precautions for Handling Electrostatic Sensitive Devices
ESD Man-Machine (MM) Model = 1
–
NF2 (Note 3)
rd
0.65
13.5
15.5
dB
Note 1: Performance is guaranteed only under the conditions listed in this Table and is not guaranteed over the full operating or storage temperature ranges. Operation at elevated
temperatures may reduce reliability of the device.
Note 2: NF of device only. Input RF connector, board, and input matching network loss de-embedded from measurement.
Note 3: NF of device and matching network. Input RF connector and board loss de-embedded from measurement.
Typical Performance Characteristics
(TOP = +25 °C, Characteristic Impedance [ZO] = 50 Ω, VDD = 3 V, IDD = 20 mA, Includes a 2.4 GHz Matching Network, Unless Otherwise
Noted)
Figure 3. Typical IV Curves
Figure 4. Small Signal Gain vs Frequency, PIN = –20 dBm
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DATA SHEET • SKY65050-372LF LOW NOISE TRANSISTOR
Figure 5. Input Return Loss vs Frequency, PIN = –20 dBm
Figure 6. Reverse Isolation vs Frequency, PIN = –20 dBm
Figure 7. Output Return Loss vs Frequency, PIN = –20 dBm
Figure 8. NF vs Frequency, Input RF Connector and Board Loss
De-Embedded From Measurement
Figure 9. Gain vs Input Power, F = 2.4 GHz
Figure 10. Minimum NF and Associated Gain vs Frequency,
IDD = 15 mA
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DATA SHEET • SKY65050-372LF LOW NOISE TRANSISTOR
Figure 11. Minimum NF and Associated Gain vs Drain Current,
F = 2.4 GHz
Evaluation Board Description
Package Dimensions
The SKY65050-372LF Evaluation Board is used to test the
performance of the SKY65050-372LF low noise transistor. An
assembly drawing for the Evaluation Board is shown in Figure 12.
The Evaluation Board schematic diagram is shown in Figure 13.
Table 6 provides the Bill of Materials (BOM) list for Evaluation
Board components.
The PCB layout footprint for the SKY65050-372LF is shown in
Figure 14. Typical case markings are shown in Figure 15.
Package dimensions for the 4-pin SC-70 are shown in Figure 16,
and tape and reel dimensions are provided in Figure 17.
The board is populated for 2.4 GHz operation and contains a
separate probe footprint for general device testing or source and
load pull characterization. The board is provisioned with two RF
connectors and a 3-pin DC launch. The RF connector and board
loss up to component C1 is approximately 0.15 dB at 2.4 GHz.
Board material is 10 mil thick VT47 FR4 with 1 oz. copper
cladding. RF input and output traces are 50 Ω.
Evaluation Board Test Procedure
Step 1: Connect RF test equipment to amplifier input/output SMA
connectors.
Step 2: Connect DC ground.
Step 3: Connect VDD to a +3 V supply with a current limit of
60 mA. Verify that the board draws approximately 20 mA.
Package and Handling Information
Since the device package is sensitive to moisture absorption, it is
baked and vacuum packed before shipping. Instructions on the
shipping container label regarding exposure to moisture after the
container seal is broken must be followed. Otherwise, problems
related to moisture absorption may occur when the part is
subjected to high temperature during solder assembly.
THE SKY65050-372LF is rated to Moisture Sensitivity Level 1
(MSL1) at 260 °C. It can be used for lead or lead-free soldering.
Care must be taken when attaching this product, whether it is
done manually or in a production solder reflow environment.
Production quantities of this product are shipped in a standard
tape and reel format. For packaging details, refer to the Skyworks
Application Note, Discrete Devices and IC Switch/Attenuators Tape
and Reel Package Orientation, document number 200083.
Step 4: Apply RF signal or noise source and verify performance
detailed in Table 5.
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DATA SHEET • SKY65050-372LF
Figure 12. SKY65050-372LF Evaluation Board Assembly Diagram
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DATA SHEET • SKY65050-372LF LOW NOISE TRANSISTOR
Figure 13. SKY65050-372LF Evaluation Board Schematic
Table 6. SKY65050-372LF (SC-70 Package) Evaluation Board Bill of Materials
Component
Value
Size
0402
Manufacturer/Part Series
C1
20 pF
Murata GJM
C2
8.2 nH
0402
Coilcraft CS
C3
0.1 pF
0402
Murata GJM
C4, C7, C8, C13
DNP
C5
1000 pF
0402
Murata GRM
C6
10 pF
0402
Murata GRM
C9
1.8 pF
0402
Murata GRM
C10
0.2 pF
0402
Murata GJM
C11
3.3 nH
0402
TDK MLG
C12
6.8 nH
0402
TDK MLG
C14
1000 pF
0402
Murata GRM
C15
1000 pF
0402
Murata GRM
L1
1.5 pF
0402
Murata GJM
L2
3.3 nH
0402
Coilcraft CS
L3
1.6 nH
0402
TDK MLG
L4
3Ω
0402
Panasonic
L5
0Ω
0402
Panasonic
R1
2.2 nH
0402
TDK MLG
R2
20 Ω
0402
Panasonic
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DATA SHEET • SKY65050-372LF LOW NOISE TRANSISTOR
Figure 14. SKY65050-372LF PCB Layout Footprint
Figure 15. Typical Part Markings
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DATA SHEET • SKY65050-372LF LOW NOISE TRANSISTOR
Figure 16. SKY65050-372LF 4-Pin SC-70 Package Dimensions
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DATA SHEET • SKY65050-372LF LOW NOISE TRANSISTOR
Figure 17. SKY65050-372LF Tape and Reel Dimensions
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DATA SHEET • SKY65050-372LF LOW NOISE TRANSISTOR
Ordering Information
Model Name
SKY65050-372LF Low Noise Transistor
Manufacturing Part Number
SKY65050-372LF
Evaluation Board Part Number
SKY65050-372LF (2400 MHz)
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