OTA

OTA stands for operational transconductance amplifier, a circuit element also known as a VCA (voltage controlled amplifier), where the signal envelope creates a control voltage sent to the OTA's control pin to control gain¹. It is one of three basic analog ways of creating compression, or an envelope controlled amplifier, alongside optical and FET designs¹. OTA compression is known for a squishy, mid-focused, and punchy vintage character, as in the MXR DynaComp and Ross Compressors². OTA-based phasers, often six-stage designs, are known for a lush, shimmery, chewy, and jet-like sound that differs from FET-based phasers³⁴. OTAs also appear in other circuits, such as the LM13600 dual OTA chip used in a current-controlled state variable filter⁵.