10-Gb/s 0.13-μm CMOS Inductorless Modified-RGC Transimpedance Amplifier

This paper presents an inductorless 0.13-mu m CMOS TIA structure that is a modified version of a regulated cascode (RGC) TIA. An immittance converter is incorporated to reduce power consumption while increasing transimpedance gain. Measured 3-dB bandwidth is 7 GHz, sufficient for 10-Gb/s operation, in the presence of 250 fF capacitance at the TIA input, representative of typical CMOS photodiode capacitance. The transimpedance gain of the single-stage TIA is 50 dB Omega, and the group-delay variation is less than +/- 19 ps over the 3-dB bandwidth. The circuit occupies an active area of 180 mu m x 90 mu m and consumes 7 mW from a 1.5-V supply. The measured average input-referred current noise of the TIA is 31 pA/root Hz. Simulations and analysis show that the proposed single-stage TIA architecture is capable of achieving improvement in the transimpedance limit over a single-stage RGC TIA designed for the same data rate and the same input photodiode capacitance. A comparison of measurement results to published TIAs also demonstrates the competitive performance of the proposed TIA in terms of the TIA transimpendance gain, band-width, area, and power consumption.