MSA-2743-TR1 HP [Agilent(Hewlett-Packard)], MSA-2743-TR1 Datasheet - Page 11

• Manufacturer Part Number: MSA-2743-TR1
• Description: Cascadable Silicon Bipolar Gain Block MMIC Amplifier
• Manufacturer: HP [Agilent(Hewlett-Packard)]

is a safety feature and can be
omitted from the circuit, a typical
value for R3 is 1K . Rc is a
feedback element that keeps I
constant. The value of Rc is
approximated by assuming a 0.5V
drop across it; see equation below.
For 50 mA I
typical value for R1 is 560 and
R2 is 110 . A CAD program such
as Agilent Technologies ADS
recommended to determine the
values of R1 and R2 at other bias
levels. The value of the RF choke
should be large compared to 50 ,
typical value for a 1.9 GHz ampli-
fier would be 22 nH. The DC
blocking capacitors are calculated
as described above. A typical
value for C3 would be 1.0 uF.
Rc = 0.5
The active bias solution will only
require about a 1.3V difference
between Vcc and V
stability over temperature. For
more details on the active bias
circuit please refer to application
note AN-A003 Biasing MODAMP
MMICs.
Figure 4. Active Bias Circuit.
1.9 GHz Design
To illustrate the simplicity of using
the MSA-2743, a 1.9 GHz amplifier
for PCS type applications is
presented. The amplifier uses a
5.25V, 50 mA supply. The input and
C1
I
d
27x
d
, 5Volt Vcc bias, a
C3
V
d
R3
RFC
R1
d
for good bias
C2
Rc
R2
®
d
is
Vcc
output of the MSA-2743 is already
well matched to 50 and no
additional matching is needed.
Figure 5. Schematic of 1.9 GHz Circuit.
A schematic diagram of the
complete 1.9 GHz circuit with DC
biasing is shown in Figure 5. DC
bias is applied to the MSA-2743
through the RFC at the RF Output
pin. The power supply connection
is bypassed to ground with
capacitor C3. Provision is made
for an additional bypass capacitor,
C4, to be added to the bias line
near the +5 volt connection. C4
will not normally be needed unless
several stages are cascaded using
a common power supply.
The input terminal of the
MSA-2743 is not at ground
potential, an input DC blocking
capacitor is needed.
The values of the DC blocking and
RF bypass capacitors should be
chosen to provide a small reac-
tance (typically < 5 ohms) at the
lowest operating frequency. For
this 1.9 GHz design example,
18 pF capacitors with a reactance
of 4.5 ohms are adequate. The
reactance of the RF choke (RFC)
should be high (i.e., several
hundred ohms) at the lowest
frequency of operation. A 22 nH
inductor with a reactance of
262 ohms at 1.9 GHz is sufficiently
high to minimize the loss from
circuit loading.
C1=18 pf
27x
22 nH
RFC=
11
C2=18 pF
Rc=27
C3=330 pF
Vcc=5.25V
Table 2. Component Parts List for the
MSA-2743 Amplifier at 1.9 GHz.
R1
RFC
C1,C2
C3
The completed 1.9 GHz amplifier
for this example with all compo-
nents and SMA connectors
assembled is shown in Figure 6.
Figure 6. Complete 1.9 GHz Amplifier.
Performance of MSA-2743 1.9 GHz
Amplifier
The amplifier is biased at a Vcc of
5.25 volts, I
measured gain, noise figure, input
and output return loss of the
completed amplifier is shown in
Figure 7. Noise figure is a nominal
4.0 to 4.1 dB from 1800 through
2000 MHz. Gain is a minimum of
15.1 dB from 1800 MHz through
2000 MHz. The amplifier output
intercept point (OIP3) was
measured at a nominal +28.5 dBm.
P
Figure 7. Gain, Noise Figure, Input and Output
Return Loss Results.
-1dB
-10
-20
-30
20
10
0
1.5
measured +15.0 dBm.
Agilent Technologies
MSA-2X43
d
1.7
27 chip resistor
22 nH LL1608-FH22N
18 pF chip capacitor
330 pF chip capacitor
of 50 mA. The
IN
FREQUENCY (GHz)
1.9
OUT
IP 4/00
Vcc
2.1
2.3