SKY12207-478LF Datasheet, PDF (10/18 Pages) Skyworks Solutions Inc. – SKY12207-478LF 0.9-4.0 GHz 50 W High Power Silicon PIN Diode SPDT Switch

DATA SHEET • SKY12207-478LF 50 W PIN DIODE SPDT SWITCH
Figure 10. Transmit Power Derating, Maximum CW Incident
Power (Insertion Loss = 0.3 dB) vs Temperature on Bottom of
Package Ground Plane
Figure 12. SKY12207-478LF Equivalent Circuit Diagrams
Figure 11. Transmit Power Derating, Maximum CW Incident
Power (Insertion Loss = 0.3 dB) vs Temperature on Bottom of
Printed Circuit Board
Evaluation Board Description
The SKY12207-478LF Evaluation Board is used to test the
performance of the SKY12207-478LF PIN Diode SPDT switch. An
assembly drawing for the Evaluation Board is shown in Figure 13.
The layer detail is provided in Figure 14.
The SKY12207-478LF is designed to handle very large signals.
Sufficient power may be dissipated by this switch to cause
heating of the PIN diodes contained in the switch. It is very
important to use a printed circuit board design that provides
adequate cooling capability to keep the junction temperature of
the PIN diodes below their maximum rated operating temperature.
As indicated in Figure 10, the x-axis temperature is referenced to
the bottom of the QFN package. A printed circuit board with a very
low thermal resistance and external heat sink design must be
used to achieve the results shown in this Figure. The power
derating curve with the x-axis temperature referenced to the
bottom of the printed circuit board is provided in Figure 11.
The evaluation circuit is designed to facilitate control of the
SKY12207-478LF transmit/receive switch with bias signals
derived from positive voltages. The state of the PIN diodes within
the SKY12207-478LF is controlled with 5 V applied to the ANT
port and bias voltages of either 28 V or 0 V applied to the
remaining bias inputs (RX and TX ports). The switch state circuit
diagrams are shown in Figure 12.
The value of resistor R1, 80 Ω, is selected to provide 50 mA of
forward current through the "on" series diode with 5 V applied to
the ANT port bias pin. The R2 resistance value of 540 Ω is
selected to produce approximately 50 mA of forward bias current
in the RX shunt diode with a source voltage of 28 V.
The magnitudes of the voltages applied to the TX and RX ports
determine which of the RX or TX series diodes is biased into
forward conduction. For example, to place the SKY12207-478LF
into the transmit state, 0 V is applied to the TX port (which forward
biases the diode between pins 2 and 14), 28 V is applied to the RX
port (which reverse biases the diode between pins 2 and 7), and
0 V is applied to the RX_BIAS port (which applies a forward bias
through R2 to the diode connected between pins 7 and 9).
The component values shown in the Evaluation Board circuit
diagram (Figure 15) were selected to optimize performance in the
2.0 to 3.5 GHz band.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [e-mail] • www.skyworksinc.com
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February 14, 2013 • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • 201678C