| 摘要 |
A differential voltage controlled oscillator and a quadrature voltage controlled oscillator using coupling of a transformer are provided to obtain a broadband tuning range while reducing a voltage oscillation gain. A resonant circuit(230) includes a transformer, a first variable capacitance part, a second variable capacitance part, a third variable capacitance part, and a fourth variable capacitance part, and oscillates frequencies according to a first control voltage and a second control voltage. A primary coil of the transformer is connected between a first node and a third node. A secondary coil of the transformer is connected between a second node and a fourth node. A first amplifying circuit(250A) includes a first PMOS transistor and a second PMOS transistor, and differentially amplifies an oscillation frequency outputted from the resonant circuit. The first PMOS transistor is connected between a power voltage and the first node. The second PMOS transistor is connected between the power voltage and the second node. A second amplifying circuit(250B) includes a first NMOS transistor and a second NMOS transistor, and differentially amplifies an oscillation frequency outputted from the resonant circuit. The first NMOS transistor is connected between the third node and a fifth node. The second NMOS transistor is connected between the fourth node and the fifth node. |
