PMB2349 Просмотр технического описания (PDF) - Infineon Technologies

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PMB2349

Wireless Components Optimized RF/IF Dual PLL Frequency Synthesizer

Infineon Technologies 

Confidential

PMB 2349

preliminary

Functional Description

Asynchronous Mode:

The serial data is written directly to the data registers of the addressed counter

with the Enable pulse. As each counter is loading the new starting value after it

is decremented to „zero“, the counters changes therefore their counter values

asynchronously to the others.

Synchronous Mode (only for RF):

In this mode counter programming is controlled by the R- and N-counters. The

serial data (exception: higher part of long control data format) is first written with

the Enable pulse to the corresponding shadow registers. From there the values

for R-counter, A-/N-counter and charge pump current values of short/long con-

trol data format are loaded into the corresponding data register when the N-

counter reaches „zero+1“. Therefore the change of all counter states is syn-

chronised to the reloading of the N-counter to avoid additional phase error

caused by the programming. The transfer of the charge pump current values

into the corresponding data register is tied to the N-counter loading, but follows

the loading of the N-data register in the distance of one N-counter dividing ratio.

This guarantees that a new PD-current value becomes valid at the same time

when the counters are loaded with the new data.

Synchronous programming sequence:

1. Setting of synchronous counter programming by bit c13 of long control data

format.

2. Programming of the R-counter, and optional short control data format. With

the Enable signal data is loaded into the shadow registers.

3. Programming of the A/N-counter. Data is loaded into shadow registers, the

EN-signal starts the synchronous transfer to the data registers.

Synchronous data programming is of especial advantage, when large fre-

quency steps are to be made in a short time. For this purpose a high reference

frequency can be programmed in order to achieve rapid – “rough” – transient

response. This method increases the fundamental frequency by nearly the

square root of the reference frequency ratio and therefore the settling time is

reduced. When rough lock is achieved, another synchronous data transfer is

needed to switch back to the original channel spacing. A “fine” lock in will finish

the total step response. It may not be necessary to change reference frequency,

but it make sense to perform synchronous data acquisition in any case. Espe-

cially for GSM, PCN (DCS 1800) and PCS systems the synchronous mode

should be used to achieve best performance of the PMB 2347.

Wireless Components

3-9

Specification, May 2000

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