LMX2330UTM datasheet(35/42 Pages) NSC

35 / 42 page

2.0 Programming Description (Continued)

2.4 IF R REGISTER

The IF R register contains the IF R_CNTR, PD_POL IF, ID

o IF, and TRI-STATE IDo IF control words, in addition to two bits that

compose the F

oLD control word. The detailed descriptions and programming information for each control word is discussed in the

following sections. IF R_CNTR[14:0]

Reg. Most Significant Bit

SHIFT REGISTER BIT LOCATION

Least Significant Bit

9876543210

Data Field

Address

Field

FoLD0 FoLD2

TRI-

STATE

IDo

PD_

POL

IF R_CNTR[14:0]

2.4.1 IF R_CNTR[14:0]

IF SYNTHESIZER PROGRAMMABLE REFERENCE DIVIDER (R COUNTER)

IF R[2:16]

The IF reference divider (IF R_CNTR) can be programmed to support divide ratios from 3 to 32767. Divide ratios less than 3 are

prohibited.

Divide Ratio

IF R_CNTR[14:0]

9876543210

000000000000011

000000000000100

•

•••••••••••••••

32767

111111111111111

2.4.2 PD_POL IF

IF SYNTHESIZER PHASE DETECTOR POLARITY

IF R[17]

The PD_POL IF bit is used to control the IF synthesizer’s phase detector polarity based on the VCO tuning characteristics.

Control Bit

Description

Function

PD_POL IF

IF R[17]

IF Phase Detector

Polarity

IF VCO Negative

Tuning

Characteristics

IF VCO Positive

Tuning

Characteristics

IF VCO Characteristics

10136609

2.4.3 ID

o IF

IF SYNTHESIZER CHARGE PUMP CURRENT GAIN

IF R[18]

The ID

o IF bit controls the IF synthesizer’s charge pump gain. Two current levels are available.

Control Bit

Description

Function

o IF

IF R[18]

IF Charge Pump

Current Gain

LOW

0.95 mA

HIGH

3.80 mA

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