STA5630

Applications

Doc ID 16055 Rev 1

3/7

1

Applications

Three main applications cases are considered and described hereafter.

The first uses a passive antenna and only a single RF SAW in front of the internal LNA. It

targets low cost and medium performance applications. In this case LNA is ON and RFA is

set at minimum gain.

The second uses a passive antenna and two RF SAWs. It maximizes the performances in

presence of severe blockers. In this case LNA is ON and RFA is set at maximum gain.

The third case uses an active antenna. This solution targets applications where the GPS

antenna is far from the RF front-end. In this case the signal can be fed into either LNA or

RFA input depending on the application conditions.

STA5630 is suitable for baseband requiring 16.368/4.092 clock/RF interface and one, two or

three bits samples. It accepts reference clocks (TCXO) in the range of 10-52 MHz and

delivers a TCXO buffered copy to the baseband.

The STA5630 has two default modes selectable by an external pin (MODE):

●

MODE 0: the chip is configured to use 16.368 MHz as reference frequency,

●

MODE 1: the chip is configured to use 26 MHz as reference frequency.

Other modes are programmed through the serial interface

1.1

Block diagram

Figure 1.

Block diagram

Digital

Interface

CP

Buffer

PFD

Image

Rejection

Mixer

Complex IF

filter

GPS_CLK

/48

or

/ 96

TCXO_CLK

LNA_IN

MAG1

SIGN

/ 2

/ R

1 ÷ 63

SPI_NCS

SPI_CLK

SPI_DI

SPI_DO

<chip config >

ADC

TCXO

TP_IF_N

MAG1

AGC

CHIP_EN

LNA

RFA

RFA

Selectable BW

GPS BW = 2MHz

GALILEO BW = 4MHz

Selectable BW

GPS BW = 2MHz

GALILEO BW = 4MHz

Digital

Integrator

3

bits

MAG0

Default Mode Selector

MODE0: TCXO=16.368 MHz

MODE1: TCXO=26 MHz

RF_EN

MODE

F_LO = 3142.656 MHz

F_IF = 4.092 MHz

LNA_OUT

RFA_IN

VGA

LDO

V18_IN

V12_OUT

V12_RFOUT

LNA_EN

TP_IF_P

/ N

56 ÷ 2047

V18_IO