US 12,438,442 B1
Active variable inductor circuit
Danting Xu, Hong Kong (HK); Yue Ma, Hong Kong (HK); and Chengyong Li, Hong Kong (HK)
Assigned to Hong Kong Applied Science and Technology Research Institute Company Limited, Hong Kong (HK)
Filed by Hong Kong Applied Science and Technology Research Institute Company Limited, Hong Kong (HK)
Filed on Oct. 23, 2024, as Appl. No. 18/923,891.
Int. Cl. H02M 1/14 (2006.01); H02M 1/15 (2006.01); H02M 3/156 (2006.01); H02M 3/158 (2006.01)
CPC H02M 1/14 (2013.01) [H02M 1/143 (2013.01); H02M 1/15 (2013.01); H02M 3/1566 (2021.05); H02M 3/158 (2013.01); H02M 3/1588 (2013.01)] 20 Claims
OG exemplary drawing
 
1. An active inductor circuit comprising:
a mutual inductor device having primary windings between primary terminals and having secondary windings between secondary terminals, wherein the primary windings and the secondary windings are electrically isolated from each other and are magnetically coupled together by mutual inductance generated by currents flowing through the primary windings and the secondary windings;
an op amp having a first input connected to a first of the secondary terminals;
a ground resistor connected between a second of the secondary terminals and a second input of the op amp;
a feedback device connected between an output of the op amp and the second input of the op amp;
a modulation network connected between the output of the op amp and the first input of the op amp;
a switch in the modulation network, the switch modulating a secondary current flowing through the secondary windings of the mutual inductor device,
the modulation network modulating an output current generated at the output of the op amp and applying a modulated current to the second of the secondary terminals of the mutual inductor device;
wherein when the switch is in a first state, the secondary current has a first current value;
wherein when the switch is in a second state, the secondary current has a second current value that is greater than the first current value;
wherein when the switch is in the first state, the secondary current flowing through the secondary windings increases a primary equivalent inductance value of the first windings by mutual inductance through the mutual inductor device;
wherein when the switch is in the second state and the secondary current has the second current value, the primary equivalent inductance value is greater than the primary equivalent inductance value when the switch is in the first state,
whereby the primary equivalent inductance value is switched between two values by the switch that modulates the secondary current.