oDRV

Opto Driver

The oDRV takes the signal from the ADC, and it has to provide the amplified voltage with enough swing to drive a Mach Zehnder modulator. The high necessary output swing limits the linearity performances of the oDRV, as consequence the most challenging stage is the last of the chain. To improve the THD performances, closed loop solution are explored with different techniques to increase the BW, as zero in the loop gain or feedforward path.

Quantized Opto Driver

To modulate the Mach-Zehnder, the required voltage swing can be very high, leading to high supply voltage and power consumption to keep good the distortion performances. To improve this tradeoff, the Liquid Logic can be used : the single amplifier is sliced into multiple elements and each slice is dedicated to amplify only a portion of the input signal. You can change the DC operating point of any slice : they can work in parallel toghether (all in the same DC condition) or shifted in order to process different voltage interval of the input signal. In that way it's possible to change the gain setting with less consequences to the distortion degradation at low gain.

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