Power and Area Efficient Trans-impedance Amplifier Driving Large Capacitive Loads Based on Modified RGC Structure

Akbar Kari Dolatabadi | Mohsen Jalali

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URL :   http://research.shahed.ac.ir/WSR/WebPages/Report/PaperView.aspx?PaperID=127021
Date :  2019/10/21
Publish in :    IEEE Transactions on Circuits and Systems II: Express Briefs

Link :  https://ieeexplore.ieee.org/document/8869931
Keywords : Cross-coupled input stage , negative capacitance converter , regulated cascade , transimpedance amplifier.

Abstract :

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In this paper, an additional modification to the modified regulated cascode (RGC) transimpedance amplifiers (TIA) is applied which can greatly improve the bandwidth when the TIA has to drive a relatively large capacitive load. The cross-coupled input stage of the modified-RGC TIA is utilized as a negative capacitance converter without employing any additional active circuit and by only using an extra compensation capacitor. The method is cost-effective with no extra power budget and with very low area headroom. To confirm the efficiency of the technique, two modified-RGC TIA with and without the proposed technique are designed in a standard 0.18 m CMOS process. Post-layout simulation results with a 250 fF photodiode capacitance and a 120 fF loading capacitance show that the bandwidth without and with a compensation capacitor of 90 fF are 1.2 GHz and 3.7 GHz, respectively. The power consumption (of both cases) is about 3 mW and the area is 15 μm× 27 μm, which is increased by about 56 compared to the conventional one.