alm-1412 Avago Technologies, alm-1412 Datasheet - Page 6

• Manufacturer Part Number: alm-1412
• Description: Gps Lna-filter Front-end Module
• Manufacturer: Avago Technologies

Figure 7. Demoboard and application schematic diagram
Notes:
x The demoboard of Figure 6 is Rogers® RO4350 with typical Dk=3.48 (@10GHz).
x L3 and the module’s internal input pre-match form the input matching network. The RFin pin, pin 1, is directly connected to a shunt inductor
x This circuit demonstrates that very low noise figure is obtainable with standard 0402 chip inductors instead of high-Q wirewound inductors.
x C2 and L2 form a matching network at the output of the LNA stage, which can be tuned to optimize gain and return loss. For example, higher
x L1 is a choke which isolates the demoboard from external disturbances during measurement. It is not needed in actual application. Likewise,
x R1 is a stability-enhancing resistor.
x C9 is a DC-blocking capacitor. It is also not required in actual operation.
x Bias control is achieved by either varying the SD voltage (Vsd) with/without R2, or fixing the SD voltage to Vdd and adjusting R2 for the desired
x For low-voltage operation such as Vdd = 1.5 V or 1.0 V, R2 may be omitted and SD (Vsd) connected directly to Vdd.
x The grounding regime for the ALM-1412 is critical to achieving the PCS- and Cell-Band Rejections shown in Figure 9. Please refer to the PCB
6
that is grounded. The RF output filter blocks DC.
gain can be obtained by increasing the value of C2 but at the expense of stability. Changing the value of L2 can improve the PCS rejection,
but impacts output return loss.
C1 and C3 mitigate the effect of external noise pickup on the Vdd and SD lines respectively. These components are not required in actual
operation.
current. Typical value for R2 is 10k Ohms for 8 mA total current at Vdd = 2.85 V and Vsd = +2.60 V. For applications where it is more appropriate
to have SD (Vsd) connected to Vdd, a 12 k Ohms resistor value for R2 is suggested (where Vdd = 2.85 V).
Land Patterns section of this document for the exact locations of the grounding vias.
50-Ohms TL
2, 4, 5, 6, 7, 9, 10, 11
GND
1, 4
L3
1
2
3
SD
MATCH
INPUT
Vdd
C2
R2
R1
L2
3
C3
12
L1
FILTER
C1
8
C9
MODULE OUTLINE
Z1
50-Ohms TL