UMA1021AM

Features:

· Low phase noise
· Low current from 3 V supply
· Fully programmable main divider
· 3-line serial interface bus
· Independent fully programmable reference divider,driven from external crystal oscillator
· Hard and soft power-down control.


Application

· 900 MHz and 2 GHz mobile telephones
· Portable battery-powered radio equipment.


Pinout




Description

The device UMA1021AM is designed to operate from 3 NiCd cells, in pocket phones, with low current and nominal 3 V supplies.

The synthesizer UMA1021AM operates at RF input frequencies up to 2.2 GHz with a fully programmable reference divider. All divider ratios are supplied via a 3-wire serial programming bus.

UMA1021AM Separate power and ground pins are provided to the analog (charge pump) and digital circuits. The ground leads should be externally short-circuited to prevent large currents flowing across the die and thus causing damage. VDD1 and VDD2 must also be at the same potential (VDD). VCC must be equal to or greater than VDD for wider control range of the Voltage Controlled Oscillator (VCO), e.g. VDD = 3 V and VCC = 5 V.

The UMA1021AM charge pump current (phase detector gain) is fixed by an external resistor at pin ISET and controlled via the serial interface. Only a passive loop filter is necessary; the charge pump functions within a wide voltage compliance range to improve the overall system performance.