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Information as of 2000-01-10
 Latest information online
UMA1022M; Low cost dual frequency synthesizer for radio telephones
| Description |  |
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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. 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 controlled by the serial interface. Only passive loop filters are necessary; the charge pumps function within a wide voltage compliance range to improve the overall system performance. Suitable pin layout is chosen to minimize coupling and interference between signals entering or leaving the chip.
| Features | |
- 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.
| Datasheet | |
| Products, packages, availability and ordering | |
Please note, devices listed in the "Products, packages, availability and ordering" table marked with "WIT" are discontinued. Devices marked with "DOD" will be in the near future.
Contact your nearest sales or distributor office for the latest information on product status and availability.
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