User Guide

Frequency synthesizers

RF ASIC N7505 has a single synthesizer that is used to generate right frequencies for both TX and RX. The

synthesizer consists of:

• PLL (Phase-Locked Loop)

• loop filter

• VCO (Voltage Controlled Oscillator)

• balun

The VCO frequencies are locked by PLLs into a reference oscillator, VCTCXO (Voltage Controlled Temperature

Compensated Crystal Oscillator).

The PLLs is controlled via RFBus.

The VCOs operate at the channel frequency multiplied by two in the upper bands (for example, GSM1800/1900)

and by four in EGSM900 and GSM850. The required frequency dividers required for modulators and

demodulators are integrated in N7505.

Reference oscillators

A 38.4MHz VCTCXO is used as a reference oscillator for the frequency synthesizers.

Regulators

N7505 contains integrated regulators to supply regulated voltages for their internal circuitry and other RF

parts.

RM-170; RM-171

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