130dB-DR Transimpedance Amplifier with Monotonic Logarithmic Compression and High-Current Monitor

Receiving a high-power optical signal using a linear transimpedance amplifier (TIA) is often a very difficult task. Large input photocurrents saturate the TIA and make it insensitive to the input signal. This is especially a problem for optical sensing applications, in which the input photocurrent usually has a very wide dynamic range (DR). Various methods have been developed to overcome this limitation. The 2-stage compression concepts described here significantly improve. The DR is increased by 18 dB compared and by 10 dB. Moreover, the compression is monotonic over the full input current range. The proposed TIA responds linearly to the input currents that are smaller than the first break-point current, while larger currents are logarithmically compressed to avoid the saturation of the TIA. The lower bound on the input DR is given by the equivalent RMS input-noise and it is affected by the TIA transimpedance, which is set by the feedback resistor in the TIA. However, the BW is indirectly proportional to the transimpedance of the TIA, and therefore its minimum of 250 MHz is in the linear region, in which the overall transimpedance. Using the 2-stage compression concept, we simultaneously achieved a low equivalent RMS input-current noise of 58 nA and a very-high overdrive of 200 mA. This concept is also well suited for LAN technologies, optical data-storage systems, wireless IR links and free-space optics.