| 摘要 |
A digital-controlled circulator and a radio frequency identification reader having the same are provided to secure convenience for high integration in an MMIC(Monolithic Microwave Integrate Circuit) or an RFIC(Radio Frequency Integrate Circuit) form and reduce manufacturing cost by being composed of lumped elements such as an inductor, a resistor, and a capacitor. In a digital-controlled circulator, first and second variable inductors(311,312) are connected between a first terminal(P1) and a second terminal(P2) in series. Third and fourth variable inductors(313,314) are connected between the first terminal(P1) and a third terminal(P3) in series. A variable resistor(320) is connected between a first node(N1) and a second node(N2), wherein the first node(N1) is a connection point of the first and second variable inductors(311,312). The second node(N2) is a connection point of the third and fourth variable inductors(313,314). First, second, and third variable capacitors(331,332,333) are connected to the first terminal(P1), the first node(N1), and between the second node(N2) and a ground respectively. A logical control unit(350) provides a control value for varying each value of the first to the fourth variable inductors(311,312,313,314), the variable resistor(320), and the first to the third variable capacitors(331,332,333).
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