RF5163 Datasheet, PDF (4/12 Pages) RF Micro Devices – 3V-5V, 2.5GHZ LINEAR POWER AMPLIFIER

RF5163
Theory of Operation and Application Information
RF5163PCBA Evaluation Board
The RF5163 is a two-stage device with a nominal gain of 20dB in the 2.4GHz to 2.5GHz Industrial, Scientific, and Medi-
cal (ISM) band. The RF5163 is designed primarily for fixed IEEE802.11g/n WLAN applications requiring exceptionally
linear RF output powers of +23dBm to +28dBm.
The RF5163 requires a single positive supply of 5.0V nominal to operate to full specifications. Power control is provided
through two (2) separate and independent methods. The first method is through two (2) bias control pins (V_REG1 and
V_REG2). In most applications, both V_REG1 and V_REG2 are tied together and used as a single control input. The second
method is through the use of a dedicated Power Down (P_Down) pin. Applying less than (<) 0.6V_DC to the RF5163
P_Down pin fully turns “ON” both V_CC and V_CC1 power circuits. Applying 2.5V_DC to 3.5V_DC to the RF5163 P_Down pin
fully turns “OFF” both V_CC and V_CC1 circuits. Turning the RF5163 “ON” and/or “OFF” by using the P_Down pin is accom-
plished without regard to system voltage regulator turn-on and turn-off settling time restraints.
There is some external matching on the input and output of the RF5163, thus allowing the RF5163 to be used in other
applications outside the 2.4GHz to 2.5GHz ISM band (such as IEEE802.16d/e in the 2.3GHz band). Both the input and
output of the device require a series DC-blocking capacitor. In some cases, a capacitor used as a matching component
can also serve as the blocking cap. The circuits used on the RF5163PCBA and RF5163PCBA-WD Evaluation Boards
are optimized for V_CC=+5.0V_DC operation.
The RF5163 is not difficult to implement, however, care in printed circuit board layout and component selection is highly
recommended when implementing 2.5GHz capable circuits. Critical passive components in the RF5163PCBA Evalua-
tion Board circuit are interstage and output matching components (C13, C15, and C16). In these cases, high-Q (Quality
factor) capacitors suitable for RF application are used on the evaluation board (an evaluation board bill of material (BOM)
is available upon request). High-Q components are not required in every design, but it is strongly recommended that the
initial design be implemented with the same components used on the RF5163PCBA Evaluation Board. After establishing
initial baseline performance, less costly components may be substituted to evaluate performance impact.
The input matching inductor L1 and the DC blocking capacitor C14 helps to tune the peak of the small-signal gain
response as well as improve the linearity of the PA. The input impedance of the PA will not be 50Ω with this input match
so do not use a Smith Chart for guidance for value selection and parts placement. With a 50Ω input into the input match
as shown on the Evaluation Board schematic, the PA will perform as expected with an expected input return loss of
~-2dB. The input L1 should be placed with reference to the position as shown on the RF5163PCBA Evaluation Board
schematic.
The interstage matching capacitor, C13, along with the combined inductance of the internal bond wire, the short length
of circuit board trace, and the parasitic inductance of the capacitor, tunes the peak of the small-signal gain response. The
trace length between C13 and RF5163 pins 14 and 15 should be kept as close to the evaluation board schematic as pos-
sible.
The output matching capacitors are C15 and C16. These capacitors are placed with reference to position along trans-
mission line segments TL1 and TL2, as shown on the RF5163PCBA Evaluation Board schematic. These segments
should be duplicated as closely as possible. Due to variations in FR-4 characteristics and PCB manufacturer process
variations, some benefit is obtained from small adjustments to TL1 and TL2 length when the evaluation board is dupli-
cated. Prior to full scale manufacturing, the board layout of early prototypes should include some additional exposed
ground areas around C15 and C16 to optimize this part of the circuit. The AC coupling capacitor, C10, may be placed
very close to C15. The output match is complete at C15.
R3 at RF5163 pin 4 (P_Detect) desensitizes the P_Detect line from the value of C12. Without R3, the value of C12 may
affect error vector magnitude (EVM) under certain operational conditions.
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Rev A12 061114