STA8090GA datasheet(24/32 Pages) STMICROELECTRONICS

24 / 32 page

Electrical characteristics

STA8090GA

24/32

DS10820 Rev 5

4.8.2

Oscillator electrical specifications

This device contains two oscillators:



a 32.768 kHz oscillator/buffer for RTC circuit.



an OSCI oscillator/buffer in the RF Front-End

When used in oscillator mode, each oscillator requires a specific crystal, with parameters

that must be as close as possible to the following recommended values. When used in input

buffer mode, an external clock source must be applied.

32.768 kHz OSCI32 oscillator specifications

The 32.768 kHz OSCI32 oscillator is connected between RTC_XTI (oscillator amplifier

input) and RTC_XTO (oscillator amplifier output). It also requires two external capacitors of

18 pF(b), as shown on Figure 3.

OSCI32 is disabled by default and must be enabled by setting bit28-OSCI_EN of

PRCC_BACKUP_REG0 to have 32.768KHz oscillation when an XTAL pi-network is

connected to RTC_XTI/RTC_XTO pins.

Conversion gain from

RF input to ADC input

VGA at max gain

—

118

VGA at min gain

—

IP1dB

RF-IF-VGA input

compression point

VGA min

—

-80

dBm

IRR

Image rejection ratio

—

BWGNS/BDU -3dB IF bandwidth

—

MHz

ATT

Alias frequency rejection

F = 53 MHz

(fs = 65.474 MHz)

—30(1)

TgGNS/BDU

IF filter group delay

variation

—20(1)

1. Not tested in production.

Table 20. Synthesizer

Symbol

Parameter

Min.

Typ.

Max.

Unit

FTCXO_XTAL

Input frequency for xtal amplifier (1)

1. That amplifier can be used also as a TCXO input buffer.

MHz

RDIV

Reference divider range

NDIV

Loop divider range

2047

FLO

LO operating frequency

3142.656

MHz

Table 19. RFCHAIN – GLONASS/BeiDou filter and VGA (continued)

Symbol

Parameter

Test conditions

Min

Typ

Max

Unit

b. Using crystal with recommended characteristics as per Table 21.

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