The theory of transient intermodulation distortion

The existing theory of transient intermodulation distortion (TIM) is extended to cover the calculation of the duration of intermodulation bursts. It is shown that feedback values in excess of some 40 dB will cause large internal overshoots within the amplifier. The clipping of these overshoots due to the limited dynamic margins of the amplifier driver stages is shown to give rise to long periods during which the amplifier is in cut-off condition. The duration of these periods is calculated and the mathematical results are verified with digital and analogue simulation. Finally, the relationships of TIM, slew rate, and power bandwidth are discussed.