Transconductance amplifier using parasitic bipolar transistors to embody a constant voltage source

A transconductance amplifier, comprising:

• an active load including current mirrors;
• amplifying means provided with a pair of first and second NMOS transistors including gate terminals connected respectively to positive and negative input signal terminals and drain terminals connected to said active load, the drain terminal of said second NMOS transistor being connected to a current output terminal;
• and
• bias means provided with a pair of third and fourth NMOS transistors including gate terminals connected respectively to the positive and negative input signal terminals and drain terminals connected to a voltage source terminal, a pair of fifth and sixth NMOS transistors including gate terminals connected commonly to a bias voltage source terminal, source terminals connected to a ground terminal and drain terminals connected respectively to the source terminals of said third and fourth NMOS transistors, and a pair of first and second parasitic bipolar transistors including base terminals connected respectively to the source terminals of said third and fourth NMOS transistors, collector terminals connected to the voltage source terminal and emitter terminals connected respectively to source terminals of said second and first NMOS transistors in said amplifying means and to the ground terminal respectively through first and second current sources.