UMA1022M

The UMA1022M 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.

UMA1022M 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 UMA1022M 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.

UMA1022M Suitable pin layout is chosen to minimize coupling and interference between signals entering or leaving the chip.