Patent ID: 7728673

Claim:
A wideband active balun using Darlington pairs, comprising: two Darlington pair modules, said Darlington pair modules comprising a first Darlington pair module 1 a and a second Darlington pair module 1 b, said first Darlington pair module having an input matching circuit, said input matching circuit comprising a first capacitor 11 a, said first Darlington pair module and said second Darlington pair module having an second inductor 20 series with the second transistor 15 , said first Darlington pair module and said second Darlington pair module separately controlling base biases of first transistors 14 and base biases of second transistors 15 through first resistors 13 and bias resistors 12 respectively, said first Darlington pair module and said second Darlington pair module being stabilized through negative feedback resistors 16 separately, said first Darlington pair module and said second Darlington pair module separately having output matching circuits, said output matching circuit comprising a third capacitor 17 and an inductor 18 with a resistor 181 , said output matching circuits of said first Darlington pair module and said second Darlington pair module separately connecting to a first output 19 a and a second output 19 b, said first Darlington pair module and said second Darlington pair module separately having the inductor 18 serially connected with the resistor 181 , a current mirror 2 comprising a second resistor 24 , two transistors and a second voltage 25 , said current mirror providing a constant current source to have said first Darlington pair module and said second Darlington pair module operated in an active region, said second resistor controlling a collector bias of a third transistor 23 , said second voltage 25 providing a working voltage, wherein a phase imbalance of said first output 19 a of said first Darlington pair module is compensated through a fourth capacitor 10 ; wherein a phase imbalance of said second output of said second Darlington pair module is compensated through a second capacitor 11 b and said fourth capacitor 10 ; and wherein said fourth capacitor is a positive feedback capacitor serially connected between said third capacitor 17 and said second capacitor 11 b.