GENERAL DESCRIPTION
The OP275 is the frst amplifer to feature the Butler Amplifer front end. This new front end design combines both bipolar and JFET transistors to attain amplifers with the accuracy and low noise performance of bipolar transistors, and the speed and sound quality of JFETs. Total Harmonic Distortion plus Noise equals that of previous audio amplifers, but at much lower supply currents.
A very low l/f corner of below 6 Hz maintains a flat noise density response. Whether noise is measured at either 30 Hz or 1 kHz, it is only 6 nVHz. The JFET portion of the input stage gives the OP275 its high slew rates to keep distortion low, even when large output swings are required, and the 22 V/µs slew rate of the OP275 is the fastest of any standard audio amplifer. Best of all, this low noise and high speed are accomplished using less than 5 mA of supply current, lower than any standard audio amplifer.
Improved dc performance is also provided with bias and offset currents greatly reduced over purely bipolar designs. Input offset voltage is guaranteed at 1 mV and is typically less than 200 µV. This allows the OP275 to be used in many dc-coupled or sum ming applications without the need for special selections or the added noise of additional offset adjustment circuitry.
The output is capable of driving 600 Ω loads to 10 V rms while maintaining low distortion. THD + Noise at 3 V rms is a low 0.0006%.
The OP275 is specifed over the extended industrial (–40°C to +85°C) temperature range. OP275s are available in both plas tic DIP and SOIC-8 packages. SOIC-8 packages are available in 2500-piece reels. Many audio amplifers are not offered in SOIC-8 surface-mount packages for a variety of reasons; however, the OP275 was designed so that it would offer full performance in surface-mount packaging.

FEATURES
   Excellent Sonic Characteristics
   Low Noise: 6 nV/Hz
   Low Distortion: 0.0006%
   High Slew Rate: 22 V/s
   Wide Bandwidth: 9 MHz
   Low Supply Current: 5 mA
   Low Offset Voltage: 1 mV
   Low Offset Current: 2 nA
   Unity Gain Stable
   SOIC-8 Package
   PDIP-8 Package
  
APPLICATIONS
   High Performance Audio
   Active Filters
   Fast Amplifers
   Integrators