Philips Semiconductors

Objective specification

SA9024

900 MHz transmit modulator and 1.3 GHz

fractional–N synthesizer

1997 Aug 01

10

Functional Description Main Channel Synthesizer

& Auxiliary Synthesizer

SERIAL INPUT + PROGRAM LATCHES

MAIN DIVIDERS

NORMAL

OUTPUT

CHARGE

PUMP

INTEGRAL

OUTPUT

CHARGE

PUMP

AUXILIARY

OUTPUT

CHARGE

PUMP

MAIN

PHASE

DETECTOR

MAIN

REFERENCE

SELECT

SPEED-UP

OUTPUT

CHARGE

PUMP

REFERENCE DIVIDER

÷2

÷2

÷2

AUXILIARY

REFERENCE

SELECT

AUXILIARY

PHASE

DETECTOR

AUXILIARY DIVIDER

DATA

CLOCK

STROBE

INM1

INM2

INR

INA

FB

RN

PHP

PHI

RN

PHA

LOCK

PD1

NMAIN

FMOD

NF

16

3

FDAC

8

2

PD1

NR

PD1 + PD2

12

SA

PD2

NAUX

2

SM

PD2

2

2

14

FRACTIONAL

ACCUMULATOR

FB

1

SR01112

FDAC

8

FDAC

8

FDAC

8

Figure 4.

Synthesizer Block Diagram

Serial Programming Input

The serial input is a 3-wire input (CLOCK, DATA, STROBE) used to

program all counter ratios, DACs, selection and enable bits. The

programming data is structured into 24-bit words; each word

includes 2 or 3 address bits. Figure [5] shows the timing diagram of

the serial input. When STROBE = L, the clock driver is enabled and

on positive edges of the CLOCK, the signal on DATA input is

clocked into a shift register. When STROBE = H, the clock is

disabled and the data in the shift register remains stable.

Depending on the 2 or 3 address bits, data is latched into different

working or temporary registers. In order to fully program the

synthesizer, 3 words must be sent: A, B and C. The D word

programs all other functions within the SA9024. Those functions are