2.8.2 IF_B[13:0] - IF Synthesizer Programmable Binary Counter (B Counter) (R4[20:7])

The IF_B control word is used to setup the IF synthesizer’s B counter. The B counter is a 14-bit programmable binary counter

used in the programmable feedback divider. The IF_B control word can be programmed to values ranging from 3 to 16383. Divide

ratios less than 3 are prohibited.

Divide

Ratio

IF_B[13:0]

13

12

11

10

987654321

0

3

0000000000001

1

4

0000000000010

0

•

•••••••••••••

•

16383

1111111111111

1

2.8.3 IF_P - IF Synthesizer Prescaler Select (R4[22])

The LMX243x IF synthesizer utilizes a selectable dual modulus prescaler. An 8/9 or a 16/17 prescale ratio can be selected.

Control Bit

Register Location

Description

Function

01

IF_P

R4[22]

IF Prescaler Select

8/9 Prescaler

Selected

16/17 Prescaler

Selected

2.8.4 IF_PD - IF Synthesizer Powerdown (R4[23])

The IF_PD bit is used to switch the IF PLL between a powered up and powered down mode.

Furthermore, the IF_PD bit operates in conjuction with the IF_CPT bit to set a synchronous or an asynchronous powerdown

mode. Refer to Section 2.7.4 for more details on how to program the IF_CPT bit.

Control Bit

Register Location

Description

Function

01

IF_PD

R4[23]

IF Powerdown

IF PLL Active

IF PLL Powerdown

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