Hittite Microwave has released a PLL chip set. The HMC983LP5E DC to 7GHz, fractional-N divider and frequency sweeper and the HMC984LP4E low noise, digital phase-frequency detector and charge pump form a PLL chip set for PLL and FMCW (frequency modulated continuous wave) sweeper applications.
The sweeper integrates the programmable 48bit delta-sigma modulator which allows the combined PLL to achieve unparalleled fractional frequency resolution of 180nHz, says the company. A built-in frequency sweeper enables the combined PLL to generate identical, coherent, FMCW frequency sweeps that can be linear, user-defined, automatic or triggered, claims the company.
The pump can operate at high phase detector frequencies of 125 and 175MHz in fractional and integer modes, respectively. This capability enables the chip set to utilise wide loop bandwidths which result in good phase noise performance, fast PLL locking times, and fast frequency sweeps, according to the company. The PLL chip set phase noise figure of merit performance is -231dBc/Hz in integer mode and -227dBc/Hz in fractional mode.
Although the sweeper and pump can be used separately in stand-alone applications, partitioning the PLL building blocks into two distinct devices achieves good isolation and spurious emissions performance of above -60dBc/Hz inside the loop bandwidth, says the company. Both the sweeper and pump are housed in plastic leadless surface mount packages and provide temperature stability over the -40 to 85°C operating range.
