RF2155PCBA-41X 查看數據表（PDF） - RF Micro Devices
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RF2155PCBA-41X Datasheet PDF : 10 Pages
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RF2155
Pin Function Description
Interface Schematic
1
NC
Not internally connected.
2
VCC1
Positive supply for the first stage (driver) amplifier. This is an unmatched
transistor collector output. This pin should see an inductive path to AC
VCC1
ground (VCC with a UHF bypassing capacitor). This inductance can be
achieved with a short, thin microstrip line (approximately equivalent to
RF IN
0.4nH). At lower frequencies, the inductance value should be larger (longer
microstrip line) and VCC should be bypassed with a larger bypass capaci-
From Bias
Stages
tor. This inductance forms a matching network with the amplifier stages,
setting the amplifier's frequency of maximum gain. An additional 1μF
bypass capacitor in parallel with the UHF bypass capacitor is also recom-
mended, but placement of this component is not as critical. A resistor of
39Ω from this pin to pin 3 is necessary to ensure stability under extreme
output VSWR conditions.
3
VCC2
Positive supply for the bias circuits. This pin should be bypassed with a sin-
gle UHF capacitor, placed as close as possible to the package.
4
GND
Ground connection. Keep traces physically short and connect immediately
to the ground plane for best performance.
5
GND
Same as pin 4.
6
GND1
Ground return for the first stage; this should be connected to a via very
close to the device.
7
RF IN
Amplifier RF input. This is a 50Ω RF input port to the amplifier. To improve See pin 2.
the input match over all four gain control settings, an input inductor of
6.8nH should be added. The amplifier does not contain internal DC block-
ing and, therefore, should be externally DC blocked before connecting to
any device which has DC present or which contains a DC path to ground. A
series UHF capacitor is recommended for the DC blocking.
8
PD
Power down control voltage. When this pin is at 0V, the device will be in
PD
power down mode, dissipating minimum DC power. When this pin is at 3V
the device will be in full power mode delivering maximum available gain
and output power capability. This pin should not, in any circumstance, be
higher than 3.3V. This pin should also have an external UHF and HF
To RF
Stages
bypassing capacitor.
9
NC
Not internally connected.
10
NC
Not internally connected.
11
RF OUT
Amplifier RF output. This is an unmatched collector output of the final
amplifier transistor. It is internally connected to pins 11 and 14 to provide
low series inductance and flexibility in output matching. Bias for the final
power amplifier output transistor must also be provided through one of
these pins. Typically, pin 14 is used to supply bias. A transmission line of
approximately 500mils length, followed by a bypass capacitor, is adequate.
This pin can also be used to create a second harmonic trap. A UHF and
large tantalum (1μF) capacitor should be placed on the power supply side
of the bias inductor. Pin 11 should be used for the RF output with a match-
ing network that presents the optimum load impedance to the PA for maxi-
mum power and efficiency, as well as providing DC blocking at the output.
RF OUT
From Bias
S ta g e s
12
GND
Same as pin 4.
13
GND
Same as pin 4.
14
RF OUT Same as pin 11.
15
G8
RF output power gain control 8dB bit (see specification table for logic). The
control voltage at this pin should never exceed 3.3V and a logic high
VCC2
should be at least 2.7V. This pin should also have an external UHF bypass-
ing capacitor.
Gxx
To RF
Stages
Pin Function Description
Interface Schematic
4 of 10
7628 Thorndike Road, Greensboro, NC 27409-9421 · For sales or technical
support, contact RFMD at (+1) 336-678-5570 or sales-support@rfmd.com.
Rev B9 DS080128
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