The SSM2220 is a dual， low noise， matched PNP transistor， which has been optimized for use in audio applications. The ultralow input voltage noise of the SSM2220 is typically only 0.7 nV/√Hz over the entire audio bandwidth of 20 Hz to 20 kHz. The low noise， high bandwidth （190 MHz）， and offset voltage of （200 μV maximum） make the SSM2220 an ideal choice for demand ing， low noise preamplifier applications. The SSM2220 also offers excellent matching of the current gain （ΔhFE） to about 0.5%， which helps to reduce the high order amplifier harmonic distortion. In addition， to ensure the long-term stability of the matching parameters， internal protection diodes across the base to emitter junction were used to clamp any reverse base to emitter junction potential. This prevents a base to emitter breakdown condition， which can result in degradation of gain and matching performance due to excessive breakdown current. Another feature of the SSM2220 is its very low bulk resistance of 0.3 ? typical， which assures accurate logarithmic conformance. The SSM2220 is offered in 8-lead plastic dual inline （PDIP） and 8-lead standard small outline （SOIC）， and its performance and characteristics are guaranteed over the extended industrial temperature range of ?40°C to +85°C.