SKY72300-21数据手册集成电路（IC）的时钟发生器PLL频率合成器规格书PDF

描述 Description

Skyworks SKY72300-21 direct digital modulation fractional-Nfrequency synthesizer provides ultra-fine frequency resolution,fast switching speed, and low phase-noise performance. Thissynthesizer is a key building block for high-performance radiosystem designs that require low power and fine step size.

The ultra-fine step size of less than 100 Hz allows this synthesizerto be used in very narrowband wireless applications. With propertemperature sensing or through control channels, thesynthesizer’s fine step size can compensate for crystal oscillatoror Intermediate Frequency (IF) filter drift. As a result, crystaloscillators or crystals can replace temperature-compensated orovenized crystal oscillators, reducing parts count and associatedcomponent cost. The device’s fine step size can also be used forDoppler shift corrections.

The SKY72300-21 has a phase noise floor of –90 dBc/Hz up to2.1 GHz operation as measured inside the loop bandwidth. This ispermitted by the on-chip low noise dividers and low divide ratiosprovided by the device’s high fractionality.

Reference crystals or oscillators up to 50 MHz can be used withthe SKY72300-21. The crystal frequency is divided down byindependent programmable dividers (1 to 32) for the main andauxiliary synthesizers. The phase detectors can operate at amaximum speed of 25 MHz, which allows better phase noise dueto the lower division value. With a high reference frequency, theloop bandwidths can also be increased. Larger loop bandwidthsimprove the settling times and reduce in-band phase noise.Therefore, typical switching times of less than 100 s can beachieved. The lower in-band phase noise also permits the use oflower cost Voltage Controlled Oscillators (VCOs) in customerapplications.

The SKY72300-21 has a frequency power steering circuit thathelps the loop filter to steer the VCO when the frequency is toofast or too slow, further enhancing acquisition time.

The unit operates with a three-wire, high-speed serial interface. Acombination of large bandwidth, fine resolution, and the threewire,high-speed serial interface allows for a direct frequencymodulation of the VCO. This supports any continuous phase,constant envelope modulation scheme such as FrequencyModulation (FM), Frequency Shift Keying (FSK), Minimum ShiftKeying (MSK), or Gaussian Minimum Shift Keying (GMSK).

This capability can eliminate the need for In-phase andQuadrature (I/Q) Digital-to-Analog Converters (DACs), quadratureupconverters, and IF filters from the transmitter portion of theradio system.

Please note: SKY72300-21 is being discontinued and is not recommended for new design.

特性 Features

• Spur-free operation
• 2.1 GHz maximum operating frequency
• 500 MHz maximum auxiliary synthesizer
• Ultra-fine step size, 100 Hz or less
• High internal reference frequency enables large loop bandwidth implementations
• Very fast switching speed (e.g., below 100 µs)
• Phase noise to –91 dBc/Hz inside the loop filter bandwidth @ 1800 MHz
• Software programmable power-down modes
• High-speed serial interface up to 100 Mbps
• Three-wire programming
• Programmable division ratios on reference frequency
• Phase detectors with programmable gain to provide a programmable loop bandwidth
• Frequency power steering further enhances rapid acquisition time
• On-chip crystal oscillator
• Frequency adjust for temperature compensation

简介

SKY72300-21属于集成电路（IC）的时钟发生器PLL频率合成器。由制造生产的SKY72300-21时钟发生器，PLL，频率合成器时钟发生器、PLL 和频率合成器集成电路 (IC) 可为逻辑器件提供参考信号的稳定定时脉冲，这些器件包括计算机、微控制器、数据通信系统和图形/视频发生器。这些集成电路可能包括缓冲器、驱动器、分频器、倍频器、多路复用器、合成器、扇出分配器和预分频器。