A 15-mW 7-GHz inductorless transimpedance amplifier and a 1-THz+ GBP limiting amplifier for 10GbE optical receivers

An inductorless 10 Gb/s optical receiver including a novel transimpedance amplifier (TIA) with dual feedback loop and a limiting amplifier (LA) with third-order nested feedback is presented. The current-buffer based TIA employs an active Cherry-Hooper (CH) stage in the auxiliary amplifier and reuses the tail current source to achieve 10 Gbps operation in the presence of a 1pF photodiode input capacitance. The use of nested feedback in the four stage limiting amplifier enables a gain-bandwidth-product (GBP)>1THz without the use of area-consuming inductors. Implemented in IBM 130nm CMOS technology, the optical receiver achieves a BER<10⁻¹² at 10 Gbps for an input current of 30 µA, delivering 600 mV p-p at the output of the 50 Ω buffer. Optical testing confirmed a −13.8 dBm sensitivity for a data rate of 7.5 Gbps, mainly limited by the 850nm source used for measurement. The receiver dissipates 108mW from a 1.2V supply, while occupying a core area of only 0.08 mm².