ACMD-7401
Miniature PCS Band Duplexer
Data Sheet
Description
The ACMD-7401 is a miniaturized duplexer designed
using Avago’s Film Bulk Acoustic Resonator (FBAR)
technology. The ACMD-7401 is the first duplexer built
with Avago’s innovative Microcap bonded-wafer chip
scale packaging technology. This process allows the
ultra small filters to be assembled in a molded chip-on-
board (MCOB) module that is less than 1.4 mm high with
a 5 x 5 mm footprint.
The ACMD-7401 enhances the sensitivity and dynamic range
of CDMA receivers, providing more than 50 dB attenuation
of transmitted signal at the receiver input, and more than 40
dB rejection of the transmit-generated noise in the receive
band. Typical insertion loss in the Tx channel is only 1.8 dB,
minimizing current drain from the power amplifier. Typical
insertion loss in the Rx channel is 2.2 dB, improving receiver
sensitivity.
Avago’s thin-film Bulk Acoustic Resonator (FBAR)
technology makes possible high-Q filters at a fraction
their usual size. The excellent power handling of the
bulk-mode resonators supports the high output powers
needed in PCS handsets, with virtually no added
distortion.
Features
Miniature size: less than 1.4 mm high, 5 x 5 mm footprint
Rx Band: 1930 – 1990 MHz typical performance:
Rx Noise Blocking: 44 dB
Insertion Loss: 2.2 dB typical, 3.0 dB band edge
Tx Band: 1850 – 1910 MHz typical performance:
Tx Interferer Blocking: 54 dB
Insertion Loss: 1.8 dB typical, 2.5 dB band edge
30 dBm Tx Power Handling
Applications
Handsets or data terminals operating in the US PCS
frequency band
ACMD-7401 Electrical Specifications, Z
O
= 50Ω, T
C[1]
as indicated
Symbol
S23
S23
S23
S23
S23
S22
S31
S31
S31
S31
S31
S31
S11
S33
S21
S21
S21
Parameters
Path from Antenna Port to Receiver Port
Attenuation in Transmit Band
(1850.6 – 1909.4 MHz)
Insertion Loss, lower band edge
(1930.6–1935 MHz)
Insertion Loss, mid-band
(1935–1987 MHz)
Insertion Loss, upper band edge
(1987–1989.4 MHz)
Ripple in Receive Band
Rx Port Return Loss in Receive Band
Attenuation in Receive Band
(1930.6 – 1935 MHz)
Attenuation in Receive Band
(1935–1989.4 MHz)
Insertion Loss, lower band edge
(1850.6–1853 MHz)
Insertion Loss, mid-band
(1853–1907 MHz)
Insertion Loss, upper band edge
(1907–1909.4 MHz)
Ripple in Transmit Band
Tx Port Return Loss in Transmit Band
Antenna Port Return Loss,
Tx and Rx bands
Tx-Rx Isolation, 1850.6 – 1909.4 MHz
(Transmit Band)
Tx-Rx Isolation, 1930.6–1935 MHz
(Receive Band)
Tx-Rx Isolation, 1935–1989.4 MHz
(Receive Band)
Units
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
+25°C
[1,3]
+85°C
[1,2,3,4]
–30°C
[1,2,3]
Min Typ Max
Min Typ Max
50
—
—
—
—
8.0
40
40
—
—
—
—
8.0
8.0
50
40
40
54
2.6
2.2
2.8
1.5
10
44
42
2.3
2.2
1.6
2.0
10
10
54
44
44
—
3.5
3.5
3.5
2.6
—
—
—
3.0
3.0
3.0
2.5
—
—
—
—
—
50
—
—
—
—
8.0
40
40
—
—
—
—
8.0
8.0
50
40
40
52
2.7
2.2
2.8
1.5
10
42
42
2.3
2.2
2.4
2.0
10
10
54
44
44
—
3.5
3.0
3.8
3.0
—
—
—
3.0
3.0
3.8
3.0
—
—
—
—
—
Min
50
—
—
—
—
8.0
37
40
—
—
—
—
8.0
8.0
50
38
40
Typ
52
3.2
2.2
2.7
2.0
10
42
42
2.3
2.2
1.2
2.0
10
10
54
44
44
Max
—
4.5
3.5
3.5
3.0
—
—
—
3.6
3.0
3.0
3.0
—
—
—
—
—
Path from Transmitter Port to Antenna Port
Notes:
1. T
C
is defined as case temperature, the temperature of the underside of
the duplexer where it makes contact with the circuit board. Port 1 = Tx,
Port 2 = Rx, Port 3 = Ant
2. Specifications are given at operating temperature limits and room
temperature. To estimate performance at some intermediate
temperature, use linear interpolation.
3. Specifications are guaranteed over the given temperature range,
with the input power to the Tx port equal to +29 dBm (or lower)
over all Tx frequencies. Upper transmit band edge maximum
Insertion Loss at 85°C is guaranteed to +26 dBm of input power.
For higher input power, derate maximum temperature as: Tmax =
95°C – 25°C * Pin (Watts). Input power between +26 dBm and +30
dBm is safe, but the Insertion Loss at the upper transmit band edge
will degrade slightly.
4. High temperature specifications are guaranteed with thermal pads
in thermal contact with the motherboard. (See Figure 1.)
Thermal Pads ensure good
thermal contact to the motherboard.
Figure 1. Underside of the duplexer.
2
0
-35
-40
S21 (Tx to Rx isolation), (dB)
-10
S31 (Ant-Tx), (dB)
-45
-50
-55
-60
-65
-70
1.82
-30C
25C
85C
-20
-30
-30C
25C
85C
-40
-50
1.82
1.84
1.86
1.88
1.90
1.92
1.94
1.96
1.98
2.00
2.02
1.84
1.86
1.88
1.90
1.92
1.94
1.96
1.98
2.00
2.02
FREQUENCY (GHz)
FREQUENCY (GHz)
Figure 2. Loss, Tx port to antenna port.
Figure 3. Isolation (Tx to Rx ports).
0
0
-10
S23 (Ant-Rx), (dB)
-20
-30
-40
-50
-60
1.82
-30C
25C
85C
S11 (Tx Return Loss), (dB)
-5
-10
-15
-30C
25C
85C
1.84
1.86
1.88
1.90
1.92
1.94
1.96
1.98
2.00
2.02
-20
1.82 1.84
1.86
1.88
1.90
1.92
1.94
1.96
1.98
2.00 2.02
FREQUENCY (GHz)
FREQUENCY (GHz)
Figure 4. Loss, antenna port to Rx port.
Figure 5. Return Loss, Tx port.
0
S22 (Rx Return Loss), (dB)
-5
-30C
25C
85C
-30C
25C
85C
-10
-15
-20
1.82
1.84
1.86
1.88
1.90
1.92
1.94
1.96
1.98
2.00
2.02
FREQUENCY (GHz)
Figure 6. Return loss, Rx port.
freq (1.850 GHz to 1.909 GHz)
Figure 7. Tx port impedance (8 dB circle).
3
0
S33 (Ant Return Loss), (dB)
-5
-30C
25C
85C
-30C
25C
85C
-10
-15
-20
1.82
1.84
1.86
1.88
1.90
1.92
1.94
1.96
1.98
2.00
2.02
FREQUENCY (GHz)
Figure 8. Return loss, antenna port.
freq (1.930 GHz to 1.990 GHz)
Figure 9. Rx port impedance (8 dB circle).
-30C
25C
85C
-30C
25C
85C
freq (1.850 GHz to 1.910 GHz)
freq (1.930 GHz to 1.990 GHz)
Figure 10. Antenna port impedance, Tx band (8 dB circle).
Figure 11. Antenna port impedance, Rx band (8 dB circle).
4
Applications Information
Avago’s ACMD-7401 duplexers provide high RF
performance in a very small package. However, in
order to achieve all the performance available from the
duplexer, care must be taken in the design of the board
onto which it is mounted. The purpose of this information
is to provide Avago’s recommendations on the design of
that board (called the motherboard in this note).
Areas where care in design must be observed are thermal
ground, RF ground, in/out connection design, and solder
mask/solder stencil design. These four design areas,
which are sometimes interrelated, will be considered one
at a time below.
Thermal Ground
FBAR resonators have a negative temperature coefficient
of frequency — as temperature goes up, the frequency
response of the filter shifts down in frequency. See Figure
12. Typical coefficients are 57 KHz/°C for the Tx filter and
40 KHz/°C for the Rx filter. In Figure 13, the same data are
presented with the scale narrowed down to the upper
end of the Tx band. Note that all these data are taken at
low input power levels (+10 dBm).
When input power is +29 dBm, heating in the Tx filter due
to RF losses causes the filter membranes to heat up beyond
85°C. This, in turn, causes the filter response to shift further
left (down in frequency), resulting in increased insertion
loss at the high end of the Tx band (1910 MHz). Avago
Technologies takes this into account in the manufacture
and final test of the duplexer — all specifications for
insertion loss (and other parameters) will be met at the
specified input power level and motherboard temperature.
Note that high power/high temperature testing done at
Avago is performed with the duplexer soldered down to a
test board having a very good heat sink.
0
0.0
-0.5
-10
S31 (TX to Ant Loss), (dB)
-1.0
-1.5
-2.0
-2.5
-3.0
-3.5
-4.0
S31 (Ant-Rx), (dB)
-20
-30
-30C
25C
85C
-30C
25C
85C
-40
-50
-4.5
-5.0
1.845
-60
1.82
1.86
1.90
1.94
1.98
2.02
1.855
1.865
1.875
1.885
1.895
1.905
1.915
FREQUENCY (GHz)
FREQUENCY (GHz)
Figure 12. Tx Filter Response with Temperature.
Figure 13. Tx Filter Response with Temperature (expanded).
5
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