AK1543

[AK1543] AK1543 1300MHz Delta-Sigma Fractional-N Frequency Synthesizer 1. Overview The AK1543 is a Delta-Sigma Fractional-N PLL (Phase Locked Loop) frequency synthesizer with a frequency switching function, covering a wide range of frequencies from 400 to 1300MHz. This product consists of an 18-bit Delta-Sigma modulator, a low-noise phase frequency comparator, a highly accurate charge pump, a reference divider and a dual-module prescaler (P/P+1). An excellent PLL can be achieved by combining this synthesizer with the external loop filter and VCO (Voltage Controlled Oscillator). The access to the registers is controlled via a three-lines serial interface. The operating supply voltage is from 2.7V to 5.5V; and the charge pump and serial interface can be driven by individual supply voltages. 2. Features     Delta-Sigma Fractional-N frequency synthesizer providing shorter lockup time, lower phase noise and low spurious performance Operating frequency: On-chip charge pump for fast lockup Programmable charge pump current: In a normal operating scheme, the charge pump current can be set in 16 steps, in the range from 10.6uA to 168.9uA. In a fast lockup scheme, the charge pump current can be set in 8 steps, in the range from 0.84mA to 2.32mA.        Supply Voltage: Separate power supply for the charge pump: On-chip power-saving features On-chip PLL lock detect feature: Direct output to the PFD (Phase Frequency Detector) or digital filtering output can be selected. Very l...