THAT4301

THAT 4301 Dynamics Processor, dubbed "THAT Analog Engine," combines in a single IC all the active circuitry needed to construct a wide range of dynamics processors. The 4301 includes a high-performance, exponentially- controlled VCA, a log-responding RMS-level sensor and three general- purpose opamps.

The VCA provides two opposing-polarity, voltage- sensitive control ports. Dynamic range exceeds 115 dB, and THD is typically 0.003% at 0 dB gain. In the 4301A, the VCA is selected for low THD at extremely high levels. The RMS detector provides accurate rms-to-dc conversion over an 80 dB dynamic range for signals with crest factors up to 10. One opamp is dedicated as a current-to-voltage converter for the VCA, while the other two may be used for the signal path or control voltage processing.

The combination of exponential VCA gain control and logarithmic detector response - "decibel- linear" response - simplifies the mathematics of designing the control paths of dynamics processors. This makes it easy to design audio compressors, limiters, gates, expanders, de-essers, duckers, noise reduction systems and the like. The high level of integration ensures excellent temperature tracking between the VCA and the detector, while minimizing the external parts count.