User Guide

PAMS Technical Documentation 3. System Module
NSD-5
Issue 1 05/02 Nokia Corporation Page 49
Figure 25: Block diagram of basic phase locked loop
The LMX2330L of monolithic, integrated, dual frequency synthesizers, including prescal-
ers, is to be used as a local oscillator for RF and first IF of a dual conversion transceiver.
In this explanation of LMX2330L IC, RF means the frequency range of the TX/RX UHF and
IF is the frequency range of the TX-VHF.
The LMX2330L contains dual modulus prescalers. A 64/65 can be selected for the RF syn-
thesizer and a 8/9 prescaler can be selected for the IF synthesizer. LMX2330L, which
employs a digital phase locked loop technique, combined with a high-quality reference
oscillator, provides the tuning voltages for voltage-controlled oscillators to generate very
stable low noise signals for RF and IF local oscillators. Serial data is transferred into the
LMX2330L via a three-wire interface (data, enable, clock).
Functional Description of LMX2330L
Two 15-bit R counters and the 15- and 18-bit N counters. The data stream is clocked (on
the rising edge of clock) into the DATA register, MSB first. The data stored in the shift
register is loaded into one of four appropriate latches on the rising edge of LE. The last
two bits are the control bits. The DATA is transferred into the counters as follows:
Programmable Reference Dividers (IF and RF R Counters)
If the control bits are 00 or 01 (00 for IF and 01 for RF), data is transferred from the
22 bit shift register into a latch, which sets the 15-bit R counter. Serial data format is
shown here: