Voltage controlled oscillator with wide frequency range and low noise for integrated circuit fabrication

Abstract

A voltage-controlled oscillator (10), which is comprised of two subcircuits (10a, 10b). Each subcircuit (10a, 10b) has a pair of differentially connected transistors (Q1,Q2 and Q3,Q4). The first subcircuit (10a) is an LC oscillation subcircuit, in which each transistor (Q1, Q2) has a capacitive transformer (C11,C12 and C21,C22) in its feedback loop. The second subcircuit (10b) is a current-controlled variable-capacitance subcircuit, whose feedback loop has a gain that determines the effective capacitance of the subcircuit (10b). When the subcircuits (10a, 10b) are combined, the feedback loops on each side of the differential pairs (Q1,Q2 and Q3,Q4) share the capacitive transformer (C11,C12 and C21,C22). The result is that the effective capacitance determines the oscillation frequency for the oscillator (10).

Dependencies are inferred from the claim text.