R1 REGISTER

The R1 register address bits (R1 [1:0]) are “01”.

The IF_FREQ bits selects the default IF frequency applicable to the specific CDMA system. For the LMX2502 the default IF

frequency is 440.76 MHz, and for the LMX2512 the default IF frequencies are 367.20 MHz and 170.76 MHz, depending on

variant.

Reference Frequency Selection bit (OSC_FREQ) selects either 19.20 MHz or 19.68 MHz for the reference oscillator frequency.

The internal spurious reduction scheme is controlled by the SPUR_RDT [1:0] bits. There are two different spur reduction

schemes: a continuous tracking mode and a single optimization mode. The continuous tracking mode will adjust for variations in

voltage and temperature. The single optimization mode fixes the internal compensation parameters only when the PLL goes into

the locked state. The spur reduction can also be disabled, but it is recommended that the continuous mode be used for normal

operation.

The OB_CRL [1:0] bits determine the power level of the RF output buffer. The power level can be set according to the system

requirement.

The two bits, RF_EN and IF_EN, logically select the active state of the RF synthesizer system and the IF PLL, respectively. The

entire IC can be placed in a power down state by using the CE control pin (pin 20).

R1 REGISTER

MSB

SHIFT REGISTER BIT LOCATION

LSB

23

22 21

20 19 18 17 16 15 14 13 12

11

10 98765

4

3

2

1

0

Data Field

Address

Field

R1

(Default)

IF_

FREQ

[1:0]

OSC_

FREQ

10000000

SPUR_

RDT

[1:0]

0

0101OB_

CRL

[1:0]

RF_

EN

IF_

EN

01

Name

Functions

IF_FREQ [1:0]

IF Frequency Selection

00 = 170.76 MHz (LMX2512LQ0967)

01 = 367.20 MHz (LMX2512LQ1065)

10 = 440.76 MHz (LMX2502LQ1635)

OSC_FREQ

Reference Frequency Selection

0 = 19.20 MHz

1 = 19.68 MHz

SPUR_RDT [1:0]

Spur Reduction Scheme

00 = No spur reduction

01 = Not Used

10 = Continuous tracking of variation (Recommended)

11 = One time optimization

OB_CRL [1:0]

RF Output Power Control

00 = Minimum Output Power

01 =

10 =

11 = Maximum Output Power

RF_EN

RF Enable

0=RFOff

1=RFOn

IF_EN

IF Enable

0=IFOff

1=IFOn

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