SKY65111-348LF Datasheet, PDF (13/16 Pages) Skyworks Solutions Inc. – ISM 600-1100 MHz Band 2 Watt InGaP HBT Power Amplifier

DATA SHEET • SKY65111-348LF
Application Circuit Notes
Ground, (Pins 1, 3, 8, 14). Attach all ground pins to the RF
ground plane with the largest diameter and lowest inductance via
that the layout will allow. Multiple small vias are also acceptable
and will work well under the device if solder migration is an
issue. It is extremely important that the device paddle be suffi-
ciently grounded for both thermal and stability reasons. Please
refer to the enclosed Package Footprint.
RF input (Pin 2). A lumped element matching structure for good
in-band return loss has been realized on the RF input, Pin 2. This
structure is comprised of a DC blocking capacitor (C1), low pass
LC filter (L1, C1) and at the device input, a series capacitor (C25).
This combination of devices will yield a return loss better than -
11 dB over the entire 800–1100 MHz band of interest. The
placement of C1 is not critical; it can be moved as close to L1,
C2 and C25 as desired. C25 should be placed as close to the
device pin as possible to replicate performance as measured on
the applications board.
V_CC1 (Pin 4). V_CC1 is the collector bias for the first amplifier
stage in the SKY65111. Multiple bypass capacitors, C3-C5, C17
and a series inductor, L2, have been utilized to ensure stability
both in and out of the useable bandwidth of the device. The
length of transmission line between L2 and Pin 4 is not critical;
L2 can be placed as close to the pin as possible if desired.
However, placement of L2 farther away from Pin 4 than shown
on the Applications Circuit is not recommended. C3 should also
be placed in the approximate location shown on the Applications
Circuit, but placement is not critical.
V_APC1 (Pin 5). V_APC1 is the bias control voltage input for amplifier
stages 1 and 2. Nominal operating range is between 2.6 V_DC and
2.8 V_DC, with 3 V_DC producing the minimum attenuation point.
V_APC1 may also be set to 0 V_DC, to force stages 1 and 2 into
standby mode.
V_APC2 (Pin 6). V_APC2 is the bias control voltage for amplifier
stage 3. Nominal operating range is between 2.6 V_DC and
2.8 V_DC, with 3 V_DC producing the minimum attenuation point.
A 100 pF capacitor (C19) may be used for bypassing at high
frequencies. The value of this capacitor may also be made large,
greater than 1000 pF, if longer response time is acceptable.
V_APC2 may also be set to 0 V_DC, to place amplifier stage 3 into
standby status.
V_REF (Pin 7). V_REF is the bias reference voltage for amplifier
stages 2 and 3. V_REF should be operated over the same voltage
range as V_CC, with a nominal voltage of 3.5 V_DC. Bypassing of
V_REF is accomplished with C22 and C23 which should be placed
as close to the device pin as possible.
RF_OUT, V_CC3 (Pins 9-12). RF_OUT and V_CC3 are the biasing input of
the stage 3 collectors. Bias is applied to the RF output through a
length of transmission line that is approximately 827 mils (21
mm) long. Capacitors C11-C14 provide proper RF bypassing and
should be placed as shown in the Applications Circuit. Output
matching for optimal power gain is accomplished with capacitors
C15 and C16. Spacing between these capacitors with respect to
the RF output and each other is critical and is shown on the
Component Placement Diagram. Special care must be taken
when placing these devices; their locations should not deviate
significantly from the locations as shown. If these capacitors are
not located properly, large decreases in output power and effi-
ciency will occur.
Pin 13. Pin 13 has no connection and should be left open circuit.
V_CC2 (Pins 15-16). V_CC2 is the collector bias input for the second
amplifier stage in the SKY65111. Multiple bypass capacitors,
C8-C10 have been utilized to ensure stability both in and out of
the useable bandwidth of the device. Capacitor C7 is not popu-
lated with the normal tuning configuration described above.
NOTE: In most applications V_APC1 and V_APC2 pins are directly tied
together and biased from the same control voltage. V_APC1
and V_APC2 may also be split if independent control is
desired.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [e-mail] • www.skyworksinc.com
200428 Rev. E • Skyworks Proprietary Information. • Products and product information are subject to change without notice. • February 12, 2007
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