An oscillation circuit has a voltage generator configured to generate a linearly changing voltage, a voltage level of which linearly changes as time passes, a first comparator configured to compare the linearly changing voltage with a first reference voltage, a second comparator configured to compare the linearly changing voltage with a second reference voltage having a higher voltage level than the first reference voltage, a time-to-digital converter configured to output a bit sequence signal in accordance with a time difference between a time when the first comparator detects that the linearly changing voltage matches the first reference voltage and a time when the second comparator detects that the linearly changing voltage matches the second reference voltage, and an oscillator configured to generate an oscillation signal that oscillates at a frequency according to the bit sequence signal.

A ring oscillator includes at least one oscillator stage having a first output and a second output and a start-up circuit. The start-up circuit includes a plurality of AC coupling capacitors receiving the first output and the second output, and a plurality of switches connected to the AC coupling capacitors. The start-up circuit is configured to provide a differential start-up voltage to at least one node of the oscillator using the plurality of switches and the AC coupling capacitors.

A ring oscillator includes at least one oscillator stage having a first output and a second output and a start-up circuit. The start-up circuit includes a plurality of AC coupling capacitors receiving the first output and the second output, and a plurality of switches connected to the AC coupling capacitors. The start-up circuit is configured to provide a differential start-up voltage to at least one node of the oscillator using the plurality of switches and the AC coupling capacitors.

A ring oscillator includes at least one oscillator stage having a first output and a second output and a start-up circuit. The start-up circuit includes a plurality of AC coupling capacitors receiving the first output and the second output, and a plurality of switches connected to the AC coupling capacitors. The start-up circuit is configured to provide a differential start-up voltage to at least one node of the oscillator using the plurality of switches and the AC coupling capacitors.

A ring oscillator includes at least one oscillator stage having a first output and a second output and a start-up circuit. The start-up circuit includes a plurality of AC coupling capacitors receiving the first output and the second output, and a plurality of switches connected to the AC coupling capacitors. The start-up circuit is configured to provide a differential start-up voltage to at least one node of the oscillator using the plurality of switches and the AC coupling capacitors.

An oscillation circuit has a voltage generator configured to generate a linearly changing voltage, a voltage level of which linearly changes as time passes, a first comparator configured to compare the linearly changing voltage with a first reference voltage, a second comparator configured to compare the linearly changing voltage with a second reference voltage having a higher voltage level than the first reference voltage, a time-to-digital converter configured to output a bit sequence signal in accordance with a time difference between a time when the first comparator detects that the linearly changing voltage matches the first reference voltage and a time when the second comparator detects that the linearly changing voltage matches the second reference voltage, and an oscillator configured to generate an oscillation signal that oscillates at a frequency according to the bit sequence signal.

A fast startup power oscillator transmitter includes a transistor pair that drives a resonant circuit including a tunable capacitance. A capacitor array preferably forms the tunable capacitance. A voltage booster activates the capacitor array. A clamped body bias voltage booster can set the body bias voltage of the transistor pair in one circuit. Control circuitry activates the resonant circuit through a triode-mode switch transistor in response to an input in a range of 0.3-0.6V, and preferably while controlling the substrate bias voltage of the transistor pair to increase transconductance of the cross-coupled transistor pair. In a variation, a circuit pushes a top plate voltage of one of the two capacitors to 2V.sub.DD and pulls the top plate voltage of the other to zero to give the oscillator an initial condition. In a variation, a shaped pulse drives the transistor pair to switch to a class D oscillator mode, and the triode mode switch transistor is only turned on when the oscillation signal voltage is in the range of 0.3-0.6V.

A fast startup power oscillator transmitter includes a transistor pair that drives a resonant circuit including a tunable capacitance. A capacitor array preferably forms the tunable capacitance. A voltage booster activates the capacitor array. A clamped body bias voltage booster can set the body bias voltage of the transistor pair in one circuit. Control circuitry activates the resonant circuit through a triode-mode switch transistor in response to an input in a range of 0.3-0.6V, and preferably while controlling the substrate bias voltage of the transistor pair to increase transconductance of the cross-coupled transistor pair. In a variation, a circuit pushes a top plate voltage of one of the two capacitors to 2V.sub.DD and pulls the top plate voltage of the other to zero to give the oscillator an initial condition. In a variation, a shaped pulse drives the transistor pair to switch to a class D oscillator mode, and the triode mode switch transistor is only turned on when the oscillation signal voltage is in the range of 0.3-0.6V.

The disclosure concerns an oscillator circuit (10) for a signal transmitter, the oscillator circuit (10) comprising: a resonant circuit (12) comprising a resonant inductor (LR) and a resonant capacitor (CR) parallel to the resonant inductor (LR) or comprising a crystal device, a driving branch (14) comprising a pump capacitor (CP) connected to the resonant circuit (12), a feedback branch (20) connected to the resonant circuit (12), a phase shifting circuit (22) connected to the resonant circuit (12) via the feedback branch (20), a comparator circuit (24) connected to the feedback branch (20) via the phase shifting circuit (22) and a driver circuit (28) connected to an output of the comparator circuit (24) and operable to charge the pump capacitor (CP).

The disclosure concerns an oscillator circuit (10) for a signal transmitter, the oscillator circuit (10) comprising: a resonant circuit (12) comprising a resonant inductor (LR) and a resonant capacitor (CR) parallel to the resonant inductor (LR) or comprising a crystal device, a driving branch (14) comprising a pump capacitor (CP) connected to the resonant circuit (12), a feedback branch (20) connected to the resonant circuit (12), a phase shifting circuit (22) connected to the resonant circuit (12) via the feedback branch (20), a comparator circuit (24) connected to the feedback branch (20) via the phase shifting circuit (22) and a driver circuit (28) connected to an output of the comparator circuit (24) and operable to charge the pump capacitor (CP).