UMA1022M
Overview
- Low phase noise
- Low current from 3 V supply
- Fully programmable dividers
- 3-line serial interface bus
- Input reference buffer configurable as an oscillator with external crystal resonator
- Wide compliance voltage charge pump outputs
- Two power-down input control pins. APPLICATIONS
- 900 MHz and 2 GHz digital radio telephones
- Portable battery-powered radio equipment. GENERAL DESCRIPTION The UMA1022M BICMOS device integrates prescalers, programmable dividers, a crystal oscillator/buffer and phase comparators to implement two phase-locked loops. The device is designed to operate from 3 NiCd or a single LiIon cell in pocket phones, or from an external 3 V supply. UMA1022M The synthesizers operate at RF input frequencies up to 2.1 GHz and 550 MHz. All divider ratios are supplied via a 3-wire serial programming bus. The reference divider uses a common, fully programmable part and a separate subdivider section. In this way the comparison frequencies are related to each other allowing optimum isolation between charge pump pulses. Separate power and ground pins are provided to the analog (charge pump, prescaler) and digital (CMOS) circuits. An independent supply for the crystal oscillator section allows maximum frequency stability. The ground leads should be externally short-circuited to prevent large currents flowing across the die and thus causing damage. VDD and VDDX must be at the same potential. VCCA and VCCB must be equal to each other and equal to or greater than VDD (e.g. VDD = 3 V and VCCA = 5.5 V for wider VCO control voltage range). The charge pump currents (phase detector gain) are fixed by internal resistances and contro
