Patent ID: 7924102

Claim:
An oscillator comprising: a delay cell comprising: a first symmetric load comprising a first current source-connected transistor, a first diode-connected transistor, and a first level shift circuit, wherein a drain of the first current source-connected transistor is coupled to a drain of the first diode-connected transistor, and wherein the first level shift circuit comprises a first transistor having a gate, a source and a drain, wherein the gate of the first transistor is coupled to the drain of the first current source-connected transistor and to the drain of the first diode-connected transistor, wherein the drain of the first transistor is coupled to a supply voltage node, and wherein the source of the first transistor is coupled to a gate of the first diode-connected transistor; and a control circuit that controls the level shift circuit such that the level shift circuit adjusts a gate voltage of the diode-connected transistor, wherein the adjusting of the gate voltage causes a lower swing limit of an output signal of the delay cell to be substantially constant as an oscillating frequency of the oscillator changes.