| 摘要 |
PROBLEM TO BE SOLVED: To provide an active balun that implements single-ended-to-differential conversion over a wide band by applying an appropriate bias voltage to a grounded gate FET and a grounded source FET without requiring a DC cutoff capacitor.SOLUTION: An active balun includes a cascode current source circuit 15 comprising a current mirror circuit constituted of FETs 10-12 plus a grounded gate FET 4, and configured to apply a bias to the grounded gate FET 4 and a grounded source FET 5 in accordance with a reference current supplied to the current mirror circuit such that absolute values of transconductances of the grounded gate FET 4 and the grounded source FET 5 become equal to each other. This can apply the bias such that the absolute values of the transconductances of the grounded gate FET 4 and the grounded source FET 5 become equal to each other, without requiring a DC cutoff capacitor, to implement high accuracy single-ended-to-differential conversion over a wide band. |
