Low-frequency noise measurement of optoelectronic devices

A noise measurement setup was designed with emphasis on low frequency noise characterization of optoelectronic devices. Two different low noise amplifiers can be chosen according to desired measurement quantity. By using voltage amplifier SR560, the noise floor of 280nV//spl radic/Hz can be achieved, while for current amplifier an equivalent input current get down to 10fA//spl radic/Hz both at f=100 mHz. The noise spectra can be acquired by a SR780 FFT network signal analyzer in the range from 102.4 KHz down to 244 /spl mu/Hz. The amplifiers feature built in battery power supply, which together with an effective shielding arrangement enables good low frequency interference protection in noisy environments.