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RF2363
Rev B3 DS040114
7628 Thorndike Road, Greensboro, NC 27409-9421 · For sales or technical
support, contact RFMD at (+1) 336-678-5570 or sales-support@rfmd.com.
RF2363 Theory of Operation and Application Information
The RF2363 contains two independent low noise amplifiers which have been optimized for dual-band applications in the GSM
(905MHz to 960MHz) and DCS (1805MHz to 1880MHz) frequency bands. Fabricated using heterojunction bipolar transistor
(HBT) technology, the RF2363 delivers high linear gain at a very low noise figure and low power consumption. Internal temper-
ature compensation keeps the gain tightly controlled over temperature extremes (typically less than 1dB of gain variation from
-40°C to +85°C at 2.8V). A 50
Ω input impedance allows the part to be connected to standard receiver front end filters without
additional matching components.
MODE CONTROL
The RF2363 incorporates two enable pins (EN1 and EN2) for biasing the desired LNA according to the table below.
900MHz LNA
The 900MHz LNA is a single-stage, common emitter amplifier. Since the input pin contains a DC bias, an AC coupling capacitor
is required at this pin. An external bias inductor from the output pin (RF OUT1) to VCC provides DC biasing for the amplifier tran-
sistor and assists in matching the output impedance to the next receiver stage. A capacitor having a good RF bypass character-
istic at the frequency of operation should be placed as close as possible to the supply voltage side of the bias inductor; a low
frequency bypass capacitor should also be included. The EN1 pin supplies VCC to the bias circuits of the LNA and should also
be effectively bypassed with both low and high frequency capacitors.
1900MHz LNA
The 1900MHz LNA is implemented by two common emitter stages in cascade. The first stage is biased through an external
inductor at the EN2 pin. This inductor also acts as an interstage match; a resistor in parallel with the inductor is recommended
to 'de-Q' the inductor, thus providing a broader band interstage match. An external bias inductor from the output pin (RF OUT2)
to VCC provides DC biasing for the second stage transistor and assists in matching the output impedance to the next receiver
stage. Low and high frequency bypass capacitors should be used on the supply side of both the EN2 and RF OUT2 bias induc-
tors. An AC coupling capacitor is required at the RF IN2 pin.
LAYOUT CONSIDERATIONS
To provide optimal balance of gain and linearity, a small amount of inductance is required in the ground traces of the PCB. The
recommended inductance is between 0.5 and 1.0nH, with 0.75nH used on the Evaluation Board. Depending on the applica-
tion, more gain with less linearity or more linearity with less gain may be desired. Appropriate adjustment of the ground induc-
tance can accomplish these objectives. Minimizing the ground inductance will maximize the gain at the expense of linearity
while increasing the ground inductance will increase the linearity at the expense of gain. It is important to remember that the
pin 7 ground inductance affects the performance of both LNAs, while the pin 2 ground inductance affects only the 1900MHz
LNA.
EN1
EN2
Mode
GND
GND
Power Down
GND
VCC
1900MHz LNA On
VCC
GND
900MHz LNA On
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