Gtran Corporation

Linear Technology Corporation

Xiaoqiang Shou

Ruai Yu

Kevin Cheng

A multistage amplifier may include a multistage amplifier circuit and a resistive voltage divider network. The multistage amplifier circuit may have multiple transconductance input stages, each of which may have differential inputs and an adjustable tail current input that controls the amount of the transconductance of the input stage. The resistive voltage divider network may control the closed loop gain of the multistage amplifier circuit and include multiple resistors that provide different voltage divider ratios at different points. Each point may be connected to one of the transconductance input stages. Adjustment of tail currents at the tail current inputs may control the degree to which each point affects the closed loop gain of the multistage amplifier.

Trimming gain and CMMR in difference amplifier

A transponder having a dynamic remapping circuit remaps a value of decision threshold voltage Vdtc and a value of optical power RXP to a reference voltage Vref to minimize the bit error rate BER of a communication system. The dynamic remapping circuit implements a bilinear mapping of Vdtc and RXP to Vref with three bilinear remapping constants 'a', 'b', and &#x201c;c&#x201d; selected to align a remapped value of Vdtc_opt to a selected Vdtc normalization value, Vdtc_norm. A transponder in accord with an embodiment of the invention prevents BER from exceeding a threshold value of BER whether RXP or OSNR, or both, remain constant, change continuously, or change intermittently. Constants &#x201c;a&#x201d;, &#x201c;b&#x201d;, and &#x201c;c&#x201d; are related to parameters resulting from mathematically fitting a line to data comprising Vdtc_opt versus RXP. Another embodiment comprises a method for dynamically optimizing Vdtc and RXP to Vref in a transponder with a bilinear remapping circuit.

Growing community of inventors

Westford, MA, United States of America

Xiaoqiang Shou