A 12.5Gb/s active-inductor based transmitter for I/O applications

This paper presents an improved PMOS-based active inductor circuit suitable for output driver in wireline link transmitters. Wider tuning range and higher inductive impedance in the desired bandwidth with respect to a previous reported topology is achieved using a varactor in the active inductor architecture and modifying the feedback resistor. Using the proposed active inductor, a prototype output driver for a wireline transmitter is designed in a 90nm CMOS technology. To model nonidealities of the active-inductor that affects the transmitter performance, an accurate large-signal, wide-band characterization technique, based on Least Square Estimation is described. Amplification of high frequency components of 10 Gb/s and 12.5 Gb/s transmitted signals over two kinds of NELCO channels using active inductors in the transmitter side, improves SNDR in the receiver side by 3 dB, as compared to the case with no inductor peaking, for the same power consumption. The transmitter circuit consumes 8.4 mW from a 1.2V power supply.