LIN S H. A constant gain adaptive continuous time linear equalizer[J]. Microelectronics & Computer,2024,41(7):81-88. doi: 10.19304/J.ISSN1000-7180.2023.0419
Citation: LIN S H. A constant gain adaptive continuous time linear equalizer[J]. Microelectronics & Computer,2024,41(7):81-88. doi: 10.19304/J.ISSN1000-7180.2023.0419

A constant gain adaptive continuous time linear equalizer

  • A high-speed (25 Gbps) constant gain adaptive continuous time linear equalizer (CTLE) based on 22 nm CMOS process is presented. Benefits and drawbacks of conventional CTLE architecture are analyzed, several classical adaptive equalization topologies and limitations are also introduced briefly, the necessary of new adaptive equalizer architecture is interpreted. Utilizes two signal paths which are with same DC gain and different peaking gain, combines them together with adjustable weight to adjust the equalizing gain and keep the DC gain constant, which is aimed to keep the noise tolerance of signal path stable. Detects the full band and low band signal amplitude of equalizer output with rectifier, compares them with preset difference threshold and feedbacks the result to the equalizer, result in adaptive equalizing gain adjustable. The circuit is implemented in 22 nm CMOS process with 1.8 V supply and 5 mA current consumption. The simulation results show that, a 25 Gbps input signal with insert loss of 0 - 10 dB@12.5 GHz can be well adaptive compensated with the equalizer, the output eye diagram opening and jitter is improved. The proposal adaptive equalizer is simple in structure and costs less in power and area, which is well suited for some small input signal and noise/power/area sensitive scenarios, like high speed optical communication front end transceivers.
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