ATF521P8 Avago Technologies US Inc., ATF521P8 Datasheet - Page 17
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ATF521P8
Manufacturer Part Number
ATF521P8
Description
Manufacturer
Avago Technologies US Inc.
Datasheet
1.ATF521P8.pdf
(23 pages)
Specifications of ATF521P8
Configuration
Single Dual Source
Drain-gate Voltage (max)
-5 to 1V
Operating Temperature (max)
150C
Operating Temperature Classification
Military
Mounting
Surface Mount
Lead Free Status / Rohs Status
Compliant
PCB Layout
A recommended PCB pad layout for the Leadless Plastic
Chip Carrier (LPCC) package used by the ATF‑521P8 is
shown in Figure 10. This layout provides plenty of plated
through hole vias for good thermal and RF grounding. It
also provides a good transition from microstrip to the
device package. For more detailed dimensions refer to
Section 9 of the data sheet.
Figure 10. Microstripline Layout.
RF Grounding
Unlike SOT packages, ATF‑521P8 is housed in a leadless
package with the die mounted directly to the lead
frame or the belly of the package shown in Figure 11.
Figure 11. LPCC Package for ATF-521P8.
Figure 12. ATF-521P8 demoboard.
17
Pin 7 (Drain)
Pin 8
Pin 6
Pin 5
Bottom View
J1
Pin 1 (Source)
Pin 2 (Gate)
Pin 3
Pin 4 (Source)
C1
C4
C3
R4
R2
short
L1
0
R1
R3
C6
C7
C5
C8
J2
This simplifies RF grounding by reducing the amount
of inductance from the source to ground. It is also
recommended to ground pins 1 and 4 since they are
also connected to the device source. Pins 3, 5, 6, and 8
are not connected, but may be used to help dissipate
heat from the package or for better alignment when
soldering the device.
This three‑layer board (Figure 12) contains a 10‑mil layer
and a 52‑mil layer separated by a ground plane. The first
layer is Getek RG200D material with dielectric constant
of 3.8. The second layer is for mechanical rigidity and
consists of FR4 with dielectric constant of 4.2.
High Linearity Tx Driver
The need for higher data rates and increased voice
capacity gave rise to a new third generation standard
know as Wideband CDMA or UMTS. This new standard
requires higher performance from radio components
such as higher dynamic range and better linearity. For
example, a WCDMA waveform has a very high peak to
average ratio which forces amplifiers in a transmit chain
to have very good Adjacent Channel Leakage power
Ratio or ACLR, or else operate in a backed off mode.
If the amplifier is not backed off then the waveform is
compressed and the signal becomes very nonlinear.
This application example presents a highly linear
transmit drive for use in the 2.14GHz frequency range.
Using the RF matching techniques described earlier,
ATF‑521P8 is matched to the following input and output
impedances: