A current mode equalizer for an optical disc front-end

A 1.2 V current-mode 7th-order Bessel low pass filter (LPF) with programmable boosting gain for an optical disc front-end is presented. The wide cut-off frequency tuning is achieved by using current-mode buffers, triode region MOS resistors and varactors. The constant gm biasing and the current-mode oscillator ensure that frequency characteristics are robust to process, voltage and temperature variations. It covers a wide frequency tuning range of 1-140 MHz and speeds of CD 4x - BD 8x, for CD/DVD/BD. It has a low power consumption of 19 mW and a small size of 0.167 mm², and is fabricated with 0.13 mum CMOS technology.