On-chip jitter tolerance measurement technique with independent jitter frequency modulation from VCO in CDR

Abstract

We present an on-chip measurement technique to characterize the jitter tolerance of a clock and data recovery (CDR) circuit. The proposed jitter modulation scheme incorporates a modulated-charge-pump and a pulse generation circuits to apply a periodic triangular form voltage directly to the control voltage of CDR circuit. This jitter frequency generation scheme independent from the VCO in the CDR allows a wide and linear control of jitter. The modulated jitter amplitude range was 0.05–2 UIpp at 10 MHz, and the jitter frequency range was 100 KHz–20 MHz. The circuit was fabricated in 65 nm CMOS, and the jitter tolerance was successfully measured at 5 Gbps with a 2⁷-1 PRBS pattern. The accuracy was within 10% error from the external BER equipment measurement result. The whole CDR circuit consumes 29.9 mW at a supply voltage of 1.2 V.