10Gbps class parallel optical receiver module with low inter-channel crosstalk

Abstract

For future high-end high data rate system, 10 Gb/s optical receiver array with low inter-channel crosstalk is realized by exploiting an InGaP/GaAs HBT technology in a three-dimensional multilayer LTCC (low temperature co-firing ceramics) module. In chapter II, as a preliminary research, single ended TIA circuit investigation shows that proposed inductive buffer peaking technique gives most effective results in bandwidth extension with low power consumption. IC evaluation of inductive buffer peaking TIA with 3nH on-chip inductor shows 8.9GHz of bandwidth with 65mW power consumption. In chapter III, Single channel InGaP/GaAs HBT TIA for multi channel receiver with three cascading neutralization gain stages shows a bandwidth of 7.5GHz with fully differential I/O. Especially in this work, low supply voltage operation circuit maintaining differential topology is focused due to the limitations in conventional wideband differential gain stage. In chapter IV, novel LTCC module structure for parallel receiver enabled to get rid of on-chip buses for supply voltage and ground which causes two significant interchannel crosstalk paths. Frequency domain measurement revealed that LTCC embedded bus module shows -27 dB crosstalk at 5 GHz and -15 dB at 10 GHz. BER test showed that LTCC embedded bus module has input sensitivity of -9.5dBm for the error rate of $10^{-12}$. Careful network calculation based on measured BER shows that input sensitivity of LTCC embedded bus can be improved to -12.5dBm with conventional device technology. LTCC embedded bus module shows only 0.8dB penalty and its clear significance in suppressing inter-channel crosstalk at 10Gbps comparing to any other research results. On the basis of this remarkable modification, LTCC embedded bus module shows successful receiver specifications to be adapted to OIF VSR5 link configuration without any link budget degradation.