An Inductorless 6-GHz Variable Gain Differential Transimpedance Amplifier in 0.18-μm SiGe BiCMOS

Design of Differential Variable-Gain Transimpedance Amplifier in 0.18 µm SiGe BiCMOS

“…The VLC transceiver consists of a transmitter and a receiver module with the transmitter having a photodiode and the receiver having a photodetector to transmit and receive the light signal respectively [3][4][5][6][7]. A key limitation of VLC systems is the low efficiency of the electro-optical conversion for the photodiode and vice versa which is solved by improvements in LED efficiency as well as the need for larger photodetectors in the receiver to absorb sufficient light [1,2].…”

“…A key limitation of VLC systems is the low efficiency of the electro-optical conversion for the photodiode and vice versa which is solved by improvements in LED efficiency as well as the need for larger photodetectors in the receiver to absorb sufficient light [1,2]. In the receiver module, the TIA is the first circuit block after the photodetector that converts its current output into voltage [4][5][6][7]. As the first block, the TIA determines important parameters such as the bandwidth, noise, sensitivity and dynamic range, for subsequent blocks and thus, for the entire VLC system [3][4][5][6][7].…”

“…In the receiver module, the TIA is the first circuit block after the photodetector that converts its current output into voltage [4][5][6][7]. As the first block, the TIA determines important parameters such as the bandwidth, noise, sensitivity and dynamic range, for subsequent blocks and thus, for the entire VLC system [3][4][5][6][7]. Silicon-based processes, such as the complementary metal-oxide semiconductor (CMOS) and Silicon-Germanium (SiGe), have been widely used for previous TIA designs due to the fact of its technological maturity, low-cost, high reliability at high frequency and on-chip integrability with photodiodes and photodetectors [4][5][6][7].…”

“…As the first block, the TIA determines important parameters such as the bandwidth, noise, sensitivity and dynamic range, for subsequent blocks and thus, for the entire VLC system [3][4][5][6][7]. Silicon-based processes, such as the complementary metal-oxide semiconductor (CMOS) and Silicon-Germanium (SiGe), have been widely used for previous TIA designs due to the fact of its technological maturity, low-cost, high reliability at high frequency and on-chip integrability with photodiodes and photodetectors [4][5][6][7]. Both CMOS and bipolar-junction transistors (BJTs) can be made together on the same chip in a SiGe BiCMOS process.…”

“…The major challenge for TIA designs is to overcome the gain-bandwidth trade-off, with the bandwidth limited by the large photodetector parasitic capacitive load (C pd ) that drags down the frequency of the dominant pole located at the TIA input. Thus, most TIA designs try to compensate C pd by lowering the input impedance Z in of the TIA design [4][5][6][7][8]. A popular technique to do this is through the regulated cascode (RGC) design [4][5][6][7], while additional bandwidth-enhancing techniques, such as interleaving feedbacks [6,7], capacitive degeneration [7] and active-inductive peaking [8], are also common to introduce zeros to counter the dominant pole.…”