SKY72301-22 Datasheet | Skyworks Solutions

Description Skyworks SKY72301-22 direct digital modulation fractional-N frequency synthesizer provides ultra-fine frequency resolution, fast switching speed, and low phase-noise performance. This synthesizer is a key building block for high-performance radio system designs that require low power and fine step size. The ultra-fine step size of less than 100 Hz allows this synthesizer to be used in very narrowband wireless applications. With proper temperature sensing or through control channels, the synthesizer’s fine step size can pensate for crystal oscillator or Intermediate Frequency (IF) filter drift. As a result, crystal oscillators or crystals can replace temperature- pensated or ovenized crystal oscillators, reducing parts count and associated ponent cost. The device’s fine step size can also be used for Doppler shift corrections. The SKY72301-22 has a phase noise floor of - 95 d Bc/Hz up to 1.0 GHz operation as measured inside the loop bandwidth. This is permitted by the on-chip low noise dividers and low divide ratios provided by the device’s high fractionality. Reference crystals or oscillators up to 50 MHz can be used with the SKY72301-22. The crystal frequency is divided down by independent programmable divider ratios of 1 to 32 for the main and auxiliary synthesizers. The phase detectors can operate at a maximum speed of 25 MHz, which allows better phase noise due to the lower division value. With a high reference frequency, the loop bandwidths can also be increased. Larger loop bandwidths improve the settling times and reduce in-band phase noise. Therefore, typical switching times of less than 100 µs can be achieved. The lower in-band phase noise also permits the use of lower cost Voltage Controlled Oscillators (VCOs) in customer applications. The SKY72301-22 has a frequency power steering circuit that helps the loop filter steer the VCO when the frequency is too fast or too slow, further enhancing acquisition time. Features - Spur-free operation - 1.0...