Agilent Technologies 856290216 service manual Offset Lock Loop part of A15

Offset Lock Loop (part of A15)

The 285 MHz to 297.2 MHz sampling oscillator is used to sample the YTO. The frequency can be changed by changing the programmable dividers of the offset lock loop.

,- YTO PLL -, ,p FRACTIONAL N PLL-------\

1ST LO OUTPUT 3 . 0 - 6 . 8 1 GHz

A

/ O F F S E T L O C K L O O P - ,

300 MHz

t, - R E F E R E N C E PLL--, 600 MHz

L

-@

10 MHz ocxo

spi13e

Figure 7-5. Phase Lock Loops

Fractional N PLL (part of A14)

The fractional N PLL produces an output of 60 MHz to 96 MHz. This PLL output serves as the reference frequency for the YTO PLL. A one-to-one relationship in frequency tracking exists between the fractional N PLL and the YTO. A change of 1 MHz in the fractional

N PLL will produce a 1 MHz change in the YTO frequency.

General Troubleshooting 7-47