High-Speed Counter With Novel LFSR State Extension

This paper presents a high-speed counter architecture associated with novel LFSR state extension. By employing the proposed state extension, an
m
-bit LFSR counter with
$(\mathrm{2}^{m}-1)$
states is modified to cover
$\mathrm{2}^{m}$
states without degrading the counting rate. Based on the property that only the low-order bits are frequently switched, the proposed counter consists of two sub-counters to achieve a high counting rate and reduce the hardware complexity needed to convert an LFSR state into a binary state. The low-order sub-counter is implemented with the proposed LFSR counter, and the high-order sub-counter is designed by employing the conventional synchronous binary counter. In addition, the implemented counter takes into account the speed degradation caused by the large fan-out of the high-order sub-counter. The proposed counter designed with standard cells operates at 2.08 GHz in a 65 nm CMOS technology, and its counting rate is almost independent of the counter size.