A current-shaping technique for static MOS current-mode logic prescalers

This letter presents a current-shaping technique for static MOS current-mode logic (MCML) prescalers. Simply with two extra current-shaping capacitors the self-oscillating frequecy is increased. A current vector model is also presented to illustrate the principles. The prescaler with the current-shaping technique was fabricated in a 0.18μm CMOS technology with a reference classic one. The measurement results show that the self-oscillating frequency of the prescaler with current-shaping achieves an improvement of 10%, resulting a 6GHz highest operating frequency while the classic one could only work at 5.3GHz. Consequently, the current-shaping technique improves the maxim divide range of the prescaler with 13.2%.