A high gain wide dynamic range transimpedance amplifier for optical receivers

As the front-end preamplifiers in optical receivers, transimpedance amplifiers （TIAs） are commonly required to have a high gain and low input noise to amplify the weak and susceptible input signal. At the same time, the TIAs should possess a wide dynamic range （DR） to prevent the circuit from becoming saturated by high input currents. Based on the above, this paper presents a CMOS transimpedance amplifier with high gain and a wide DR for 2.5 Gbit/s communications. The TIA proposed consists of a three-stage cascade pull push inverter, an automatic gain control circuit, and a shunt transistor controlled by the resistive divider. The inductive-series peaking technique is used to further extend the bandwidth. The TIA proposed displays a maximum transimpedance gain of 88.3 dBΩ with the -3 dB bandwidth of 1.8 GHz, exhibits an input current dynamic range from 100 nA to 10 mA. The output voltage noise is less than 48.23 nV/√Hz within the -3 dB bandwidth. The circuit is fabricated using an SMIC 0.18 μm 1P6M RFCMOS process and dissipates a dc power of 9.4 mW with 1.8 V supply voltage.

A method to accurately measure and respond to an underwater sound pulse in a wide dynamic range

This paper presents a method to control the gain within pulse and accurately measure the amplitude of an underwater sound pulse in a wide dynamic range. In the method a loop composed of a gain controlled unit and a microcomputer is employed.This method also gives satisfactory results when there exist distortion of signal cnvelop and fluctuation of signal amplitude. The basic mathematical model of instantaneous amplitude-gain control and amplitude measurement and its hardware structure are presented. The calibration method of the system for retransmitting (responding) with required sound level is given as well.

Low Power Penalty Operation of a Wide Input Dynamic Range Cross-Phase Modulation Wavelength Converter

We successfully demonstrated low power penalty operation of a cross-phase modulated (XPM) wavelength converter using a semiconductor optical amplifier (SOA) power equalizer. We also clarified the SOA equalizing level for more adaptive wavelength conversion and achieved a power penalty of less than 1 dB over the wide input dynamic range of 15 dB.

THE ROLE OF RED NUCLEUS IN THE MODULATION OF SPINAL NOCICEPTIVE TRANSMISSION AND IN NOCICEPTION ELICITED BY MUSCLE SPINDLE AFFERENTS

Objective To analyse the antinociceptive effect of red nucleus (RN) and its role in the antinociceptive effect of muscle spindle afferents. Methods The single units of RN or wide dynamic range (WDR) neuron in the spinal cord dorsal horn were extracelluarly recorded. The effects of RN stimulation on nociceptive responses (C fibers evoked responses, C responses) of WDR neurons were observed. The influence of muscle spindle afferents elicited by intravenous administration of succinylcholine (Sch) on the spontaneous discharge of RN neurons and on C responses of WDR neurons were observed. The effect of muscle spindle afferents on C responses of WDR neurons after unilateral lesions of RN was also observed. Results Electrical stimulation of the RN produced a significantly inhibitory effect on the nociceptive responses of WDR neurons. RN neurons were excited by muscle spindle afferents. Muscle spindle afferents significantly inhibited C response of WDR neurons and this inhibitory effect was reduced by lesions of RN. Conclusion RN neurons have a significant antinociceptive effect and might be involved in the antinociceptive effects elicited by muscle spindle afferents.

Low-cost,large-coverage,and high-flexibility coherent PON for next-generation access networks:advances,challenges,and prospects[Invited]

Increasing bandwidth requirements have posed significant challenges for traditional access networks.It is difficult for intensity modulation/direct detection to meet the power budget and flexibility requirements of the next-generation passive optical network(PON)at 100G and beyond considering the new requirements.This is driving researchers to develop novel optical access technologies.Low-cost,wide-coverage,and high-flexibility coherent PON is emerging as a strong contender in the competition.In this article,we will review technologies that reduce the complexity of coherent PON(CPON),enabling it to meet the commercial requirements.Also,advanced algorithms and architectures that can enhance system coverage and flexibility are also discussed.