COIL ENHANCEMENT CIRCUIT

摘要

An enhancement circuit for enhancing the value of the inductance of a coil having a first winding (L1). The enhancement circuit comprises a second winding (L2) forming a transformer (T) with the first winding and having a first terminal (3) coupled to the ground (Vgrd) and a second terminal (4) coupled to an input of a feedback circuit. The feedback circuit senses the voltage (VL) over the coil and comprises a transconductance amplifier (gm) that amplifies and converts the sensed voltage into a current (12) injected back in the second winding. In a preferred embodiment, the coil has a pair of windings (L1a, L1b). The pair of windings (L1a, L1b) is electronically coupled between input terminals (Line+, Line-) and output terminals (POTS+, POTS-) of the low-pass filter. The improved enhancement circuit comprises a third (L2) and a fourth (L3) winding both magnetically coupled to the first (L1a) and second (L1b) windings.. The feedback circuit senses the voltage (VL) over the coil and comprises a transconductance amplifier (gm) that amplifies and converts the sensed voltage into a current (13) injected in the fourth winding (L3) via the second terminal (6) thereof.