8 TO 10.9 GHZ BAND LC VCO FOR SONET COMMUNICATION

摘要

A 8 to 10.9 GHz band LC VCO for SONET communication is provided to obtain a wide tuning range using a 0.35 micrometer CMOS process. A first current source supplies a current to an LC VCO circuit. A first node is positioned between the first current source and the LC VCO circuit. The LC VCO circuit is connected between the first node and the ground. The drains of the third MOSFET(M3) and the fourth MOSFET(M4) are connected to the first node. The sources of the third MOSFET and the fourth MOSFET are connected to the positive output side node and the negative output side node. The sources of the first MOSFET(M1) and the second MOSFET(M2) are connected to the positive output side node and the negative output side node. The drains of the first MOSFET and the second MOSFET are connected to the second current source. A first inductor is connected between the positive output side node and the negative output side node. A varactor is connected between the positive output side node and the negative output side node. An NMOS cross coupled circuit is connected to a source and a gate of a third MOSFET and a fourth MOSFET. A PMOS active load circuit is connected to the NMOS cross coupled circuit.