Low Pass Filter-Less Pulse Width Controlled PLL Using Time to Soft Thermometer Code Converter

Toru NAKURA  Kunihiro ASADA  

IEICE TRANSACTIONS on Electronics   Vol.E95-C   No.2   pp.297-302
Publication Date: 2012/02/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E95.C.297
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Integrated Electronics
PLL,  PWCO,  pulse width control,  soft thermometer code,  LPF-less,  quantization noise free,  

Full Text: FreePDF

This paper demonstrates a pulse width controlled PLL without using an LPF. A pulse width controlled oscillator accepts the PFD output where its pulse width controls the oscillation frequency. In the pulse width controlled oscillator, the input pulse width is converted into soft thermometer code through a time to soft thermometer code converter and the code controls the ring oscillator frequency. By using this scheme, our PLL realizes LPF-less as well as quantization noise free operation. The prototype chip achieves 60 µm 20 µm layout area using 65 nm CMOS technology along with 1.73 ps rms jitter while consuming 2.81 mW under a 1.2 V supply with 3.125 GHz output frequency.