A 192MHz differential XO based frequency quadrupler with sub-picosecond jitter in 28nm CMOS

A low jitter 192MHz crystal reference quadrupler leverages a new active inductor based 48MHz differential XO, two skewed inverters, a new duty cycle correction circuit, and a frequency doubler. The 192MHz quadrupler can serve as a fast, low jitter reference for a low phase noise PLL and requires far less power and area than reference multiplying PLL or MDLL circuits. The measured RMS jitter is 168fs for the XO, and 184fs for 96MHz output (192MHz divide by 2). The entire circuit, including the XO, draws 5.5mA from a 1V supply and occupies 0.045mm². To our best knowledge, this is the first reference frequency quadrupler with sub-picosecond jitter.