Design considerations for linear optically coupled isolation amplifiers

A hybrid optically coupled isolation amplifier is described which optimizes DC performance, bandwidth, physical size, and cost. The design utilizes a blend of monolithic and hybrid technologies to achieve this unique set of characteristics. The development of the linear optical coupler is traced. Optical and electronic circuit techniques are presented that combine, for the first time, precision performance with miniature packaging. Optional connections allow unipolar/bipolar and inverting/noninverting operation with both voltage and current inputs. Typical performance, based upon production runs, includes: 1000 V isolation voltage, 10 nA offset current, 1 pA//spl deg/C offset drift, 0.3 /spl mu/A barrier leakage at 60 Hz, 0.05 percent nonlinearity, and a bandwidth of over 60 kHz.