CMOS current-controlled oscillators using multiple-feedback-loop ring architectures

Three types of high-frequency current-controlled oscillators (ICO) having multiple-feedback loops are implemented in a 0.8 /spl mu/m CMOS technology. Three stage single-feedback-loop ICO (SICO) and double-feedback-loop ICO (DICO) and four-stage triple-feedback-loop ICO (TICO) are tested and compared. They all use the differential current steering logic (DCSL). Using the multiple-feedback-loop ring architectures, the operation frequencies of the ICO's are considerably improved and obtained 1.69 GHz.