Low PM noise regenerative dividers

This paper describes the various contributions to the PM noise added oscillating regenerative divide-by-two (halver). Two circuits are investigated: a 100 MHz to 50 MHz divider and a 18.4 GHz to 9.2 GHz divider. Several configurations of the 100 MHz to 50 MHz divider were studied. It was found that the broadband noise floor is determined by the thermal noise of the amplifier. We found that the thermal noise of the amplifier at the image frequency (3/2) v_o, unless eliminated, contributes to the thermal noise of the divider and thus increases the broadband noise by 3 dB. A PM noise performance of L(f)=10^-14.4/f+10^-17.9 was ultimately achieved using a medium drive power mixer. PM noise measurements of the 18.4 GHz to 9.2 GHz divider show that the broadband noise is L(10 MHz)=-168 dB below the carrier in a 1 Hz bandwidth (dBc/Hz), probably limited by the measurement system noise. A close-in noise of L(10 Hz)=-136 dBc/Hz and L(10 kHz)=-157 dBc/Hz was achieved. This design could easily be extended to 40 GHz and beyond, limited only by the availability of the mixer