AN1902 Freescale Semiconductor / Motorola, AN1902 Datasheet - Page 30

• Manufacturer Part Number: AN1902
• Description: Quad Flat Pack No-Lead (QFN)
• Manufacturer: Freescale Semiconductor / Motorola

Freescale Semiconductor, Inc.
AN1902/D
The RLC circuit model (See
Figure 32
) may be used to predict frequency bandwidth
for a package based on the transfer function between the circuit input and output
nodes. By using such a methodology, the 3dB cut-off frequency of a package can be
predicted. The graph in
Figure 32
shows the simulated frequency response for the
longest wire of a new device packaged in the 48-lead 7x7mm QFN package. The pre-
dicted value for cut-off frequency is 2.85GHz. For a device packaged in a 48ld 7x7mm
TQFP package, a value of approximately 1.5GHz would be typical.
Figure 32 Bandwidth Characteristics of 48ld QFN
In order to experimentally compare the performance of the QFN to a QFP package in
a manufacturing final test environment, an experiment was run in which known good
die from the same wafer of an RF device were packaged in 48-ld QFN and 48-ld
LQFP packages, 1000 of each test vehicle. The packaged devices were then pro-
cessed through final parametric electrical testing. Results are shown in following table.
The superior RF performance of the QFN package can be seen particularly in the
Receive Signal Strength Indicator test (RF_STAGE_GAIN, Test 3) and Signal plus
Noise and Distortion test (SINAD, Test 8). The values for the QFN package were
higher in these tests by 1.9dB and 5.1dB respectively.
30
Quad Flat Pack No-Lead (QFN)
MOTOROLA
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