Abstract: A phase-locked loop (PLL) frequency synthesizer having a two-point data modulation scheme and &Sgr;&Dgr; modulator, fractional-N architecture. In the synthesizer, data are modulated at both the PLL frequency divider and the voltage-controlled oscillator (VCO). The complementary frequency responses at these two modulation points allow the PLL bandwidth to be sufficiently narrow to attenuate phase noise from the phase detector, frequency divider, and &Sgr;&Dgr; quantization error, without adversely affecting the data. Fractional-N architecture allows a large range of reference frequencies to be used with the PLL and high frequency resolution of the output signal. The &Sgr;&Dgr; modulator modulates the feedback signal generated by the PLL frequency divider with data and quantizes the spurious signals inherent in a fractional-N design to high frequencies that the PLL loop filter can attenuate.

Abstract: The invention is directed to a process and apparatus for recovering refrigerant from a refrigeration purge stream wherein a gaseous purge stream containing a refrigerant and non-condensible gasses is countercurrently contacted with a high boiling point liquid which absorbs the refrigerant from the purge stream. Preferably a scrubbing column is used to effect countercurrent contact between the purge stream and the liquid stream.