PBL40215 Просмотр технического описания (PDF) - Ericsson

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PBL40215

RF Transceiver circuit for the Digital Enhanced Cordless Telecommunications (DECT) system

Ericsson  

PBL 402 15

RX VCO.

A fully integrated balanced VCO. The VCO frequency is controlled by the voltage applied to the VTUNE pin, and has a

negative sensitivity, i.e., as the voltage increases, the VCO frequency decreases. The tuning voltage is referenced to VCCVCO.

The VCO is buffered to provide isolation against frequency pulling and reverse injection.

A divider by 2 stage, reduces the VCO frequency by 2 for the PLL.

RX VCO Table.

Parameter

Carrier frequency range

Tuning voltage

Frequency sensitivity

Frequency pulling

Frequency pushing

Noise floor

Condition

0.4≤VT≤VCC-0.4

stand-by ↔RX

stand-by ↔TX

against VCC , CPC = 2

nominal output power

Symbol

ƒC

VT

ƒSEN

ƒPULL

ƒPUSH

NFLR

Min.

3.53

0.4

~-100

Typ.

~-280

1,0

Max.

3.65

VCC-0.4

~-460

Unit

GHz

V

MHz/V

kHz

-140

MHz/V

dBc/Hz

The PLL.

REF

R

÷2

864kHz

LO

÷2

N/N+1

M

A

Store

ƒ-φ

CP

LD

LD &

DRX

The frequency synthesiser is based on a charge pump PLL ( Phase Locked Loop ).

Counter R divides the reference clock, REF. The division ratio, R, is determined by the value of CNT_R. Counters N, A and M form a

modulus pulse swallow counter which divides the LO clock by M∗N+A . The value of M is determined by CNT_M. The value of A is

taken from the CNT_A.

A combined 3 state frequency-phase detector compares the divided REF and LO signals and controls the charge pump.The

frequency-phase comparator outputs are controlled by the CPC1-0 bits and MOD_EN. The action of the CPC bits are unsynchronised.

The action of MOD_EN is synchronised to the charge pump states, holding the charge pump in tri-state mode when MOD becomes

active.

An active high lock detect signal is provided when frequency lock has been achieved for 148 µs. The signal is available on the LD

pin and on the DRX pin when SYN_EN is active and neither of RX_EN or TX_EN are active.

The PLL is designed to work with two different reference frequencies, 10.368 MHz ( = 9 x the DECT bitrate of 1.152 MHz ) or

13.824 MHz ( = 12 x the DECT bitrate of 1.152 MHz )

16

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