Novel Tunable Equalizers with Ferroelectric BST Tunable Capacitors to Improve Signal Integrity

In this paper, the performance of a differential equalizer tuned with commercial BST capacitor is presented for the first time to improve signal integrity. The proposed equalizer is a RLC circuit where C is a 3 terminal BST capacitor supplied by manufacturer ‘STMicroelectronics’. The important features of a BST capacitor are- 1) tunability is independent of voltage polarity & 2) size is smaller than its counterparts for a given capacitance due to its high dielectric constant. The signal integrity is analyzed in terms of eye diagram at the output of a 40” lossy differential channel by using a 5Gb/s PRBS7 pattern and changing the bias to the BST capacitor.