Over-60-GHz design technology for an SCFL dynamic frequency divider using InP-based HEMTs

A toggle operation of 39-63.5 GHz without tuning has been achieved by a digital dynamic frequency divider (DFD). The DFD employs a pair of clocked inverters (CIs) with source-coupled FET logic (SCFL) and uses 0.1-μm-gate InAlAs/InGaAs/InP high electron-mobility transistors (HEMTs) of good uniformity and high performance. On a 2-in wafer, the frequency divider showed a maximum toggle frequency (f_tog,max) of 59.1±3.3 GHz and a fabrication yield of 89%. This is the highest operation frequency ever reported for a broad-band digital frequency divider. Comparison of the DFD and the static frequency divider (SFD) showed that the ratio of f_tog,max for the DFD to that for the SFD is much higher than the value expected from the linear-response theory. The comparison also showed that the ratio of the measured f_tog,max for the DFD to that for the SFD is 1.7, in contrast with the value of two expected from the circuit simulation. Delay-time analysis revealed that this 15% decrease of the ratio is due to the transmission delay of interconnections and charging time for stray capacitance