uaa1570hl NXP Semiconductors, uaa1570hl Datasheet - Page 39

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

Philips Semiconductors
8
Table 3 Programmable operating modes
8.1
Some applications of the UAA1570HL may require the use of an external LNA. Since LNA1 is self contained and includes
independent bias circuitry, it can be powered down simply by not connecting the respective supply pin or tying it to
ground. Some considerations apply to optimize performance when using an external LNA. Generally the UAA1570HL
has been optimized with approximately 15 dB of gain in the first LNA. To prevent degradation of the system noise figure
or dynamic range in subsequent system functions, such as the first mixer or synthesizer, some limitations on the nominal
effective gain and noise figure of external devices should be taken into account. The following values are not specified,
since exceeding the recommended ranges may still result in adequate dynamic performance in some 1-bit GPS system
applications.
Note: LNA2 has to be powered-up under all circumstances, i.e. its supply pin has to be connected to V
circumstances due to biasing constraints.
Table 4 Operation with external LNAs
Notes
1. The maximum external noise figure listed is that which will produce approximately a 1 dB degradation in system
2. If a high gain external LNA is used, both LNA1 and LNA2 should be removed from the signal path. However, the
1999 May 10
Normal
Partial power-down
Undefined
Complete power-down
Normal
LNA1
replacement;
note 1
LNA1/LNA2
replacement;
notes 1 and 2
Global Positioning System (GPS) front-end
receiver circuit
noise figure using the minimum recommended external gain. The maximum recommended external gain listed
results in approximately 1 dB compression in the second mixer input with an in-band continuous wave jammer
present (J/S = 35 dB) for nominal processed parts.
LNA2 supply pin has to be connected to V
OPERATING MODE SELECTION TABLES
MODE
Manual selection operating modes
MODE
V
CC(LNA1)
yes
no
no
V
CC(LNA2)
p0
0
0
1
1
yes
yes
yes
EXTERNAL GAIN
RECOMMENDED
FILTER LOSSES
p1
0
1
0
1
CABLE AND
INCLUDING
MAXIMUM
10 dB
25 dB
41 dB
CC
to retain power to the first mixer.
LNA1
yes
no
no
39
EXTERNAL GAIN
RECOMMENDED
LNA2
FILTER LOSSES
yes
no
no
CABLE AND
INCLUDING
MINIMUM
21 dB
3.5 dB
8 dB
VCO
yes
yes
no
RECOMMENDED
FILTER LOSSES
MX1, MX2,
NOISE FIGURE
CABLE AND
INCLUDING
EXTERNAL
1-BIT
MAXIMUM
yes
no
no
3.5 dB
4 dB
4 dB
UAA1570HL
Product specification
2nd LO
yes
no
no
CC
REDUCTION
INTERNAL
CURRENT
under all
6.5 mA
6.5 mA
DPLL
yes
yes
no