uaa1570hl NXP Semiconductors, uaa1570hl Datasheet - Page 11

• Manufacturer Part Number: uaa1570hl
• Description: Global Positioning System Gps Front-end Receiver Circuit
• Manufacturer: NXP Semiconductors

Philips Semiconductors
7
The programmability of the UAA1570HL and flexible
interface definitions allow the device to be configured for a
wide range of applications. To restrict the content of this
document the functional description of the device will
generally concentrate on the C/A-code application circuit
based on the default frequency plan.
The application circuit does not allow easy measurement,
calibration and documentation of the many sub-block
characteristics which ensure good system performance.
Therefore, test boards have been developed which allow
direct measurement of the sub-block characteristics.
The tables and graphs reflect the UAA1570HL
specification as derived from simulation and measured
results in these characterization board environments.
The tables and graphs do not directly specify application
board expectations. The functional description however,
focuses on the default application.
The RF system diagram (see Fig.3) illustrates the default
application of the UAA1570HL in the Philips GPS
demonstration board. In this application the UAA1570HL is
intended to be operated directly from a passive GPS
antenna through a very short antenna cable. Any cable
loss in this demonstrator adds directly to the system noise
figure and should therefore be minimized.
1999 May 10
Global Positioning System (GPS) front-end
receiver circuit
FUNCTIONAL DESCRIPTION
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LNA1 can be powered down in the UAA1570HL to
accommodate applications built around external LNAs,
typically where long antenna cable runs are required.
The first LNA is assumed to be matched with a 2nd-order
band-pass structure to provide some input selectivity,
since no dielectric or SAW filter has been used in the
demonstration board. It should be noted that low loss RF
SAW filters now make it possible to significantly improve
the jam immunity of this amplifier, by placing a SAW filter
at the output of the antenna.
On the demonstration board the first LNA is followed by a
low loss RF SAW filter (<2.4 dB).
On the demonstration board the second LNA has been
matched to 50
structure.
Finally, another identical RF SAW filter follows the second
LNA into the first mixer.
using a simple transmission line
UAA1570HL
Product specification