A compact 22-Gb/s transmitter for optical links with all-digital phase-locked loop

An optical transmitter for driving a Mach-Zehnder (MZ) Interferometer is proposed which incorporates an alldigital phase-locked loop (ADPLL) and a source-series terminated (SST) driver. The proposed optical transmitter is composed of a pattern generator, a clock synthesizer and a modulator driver. The transmitter for an external modulator should drive a large capacitance with a high voltage swing, which requires both large power consumption and area. In this work, the ADPLL is employed for the clock synthesizer to achieve a small area and low power consumption. A high voltage swing over 2 V_diff-pp with low power is obtained by adopting the SST driver. The implemented transmitter occupies only 0.58 mm² with power dissipation of 391.6 mW at operating data rate of 21.6 Gb/s.