Oscillatorless substrate bias generator

A substrate bias generator for an integrated circuit comprising:

• a low current voltage regulator coupled to the substrate of said integrated circuit for monitoring the voltage at the substrate and outputting an active clock enabling signal when the voltage varies from a predetermined level;
• a low current, self-timed clock circuit which is not free running and is responsive to the active clock enabling for generating clock signals, said clock circuit including a first stage for receiving the clock enabling signal and a second coupled to the first stage, the first and second stages outputting a plurality of clock signals;
• a pump circuit responsive to the plurality of signals to pump charge and to lower the voltage of the substrate of said integrated circuit;
• and
• wherein the self-timed clock circuit ignores any changes in the clock enabling signal until after the completion of the pumping.

A method of operating a charge pump for biasing the voltage of a substrate of an integrated circuit comprising the steps of:

• producing a clock enabling signal if the substrate voltage should be pumped;
• applying the clock enabling signal to a self-timed clock circuit;
• operating the self-timed clock circuit to generate a full cycle of clock signals in response to receiving the clock enabling signal regardless of the state of clock enabling signal during the full cycle;
• using the clock signals to cause a charge pump to pump charge to the substrate and precharging the charge pump;
• and
• then preparing to respond to a subsequent clock enabling signal.

A method of operating a charge pump for biasing the voltage of a substrate of an integrated circuit comprising the steps of:

• producing a first clock enabling signal and applying it to a self-timed clock circuit;
• in response to said first clock enabling signal, operating the self-timed clock circuit and a charge pump connected thereto in a pump mode and then a precharge mode, and only thereafter entering a quiescent state wherein the self-timed clock circuit is ready to respond to a subsequent clock enabling signal,
• including continuing said operating step to completion even if the first clock enabling signal terminals before said completion;
• and
• disregarding any clock enabling signals occurring subsequent to said first clock enabling signal but before said completion.

A method of operating a charge pump for biasing the voltage of a substrate of an integrated circuit comprising the steps of:

• in response to a demand signal, initiating the generation of a full cycle of clock signals over a predetermined intervals, said full cycle including a plurality of first clock signals followed by a plurality of second clock signals, said full cycle being generated despite any termination in the demand signal;
• using said first clock signals to cause a charge pump to pump charge to the substrate;
• and
• using said second clock signals to precharge the charge pump.

A method of operating a charge pump for biasing the voltage of a substrate of an integrated circuit comprising the steps of:

• obtaining a demand signal indicative of a demand for voltage and applying the demand signal to an input of a self-timed clock circuit;
• operating the self-timed clock circuit in response to said demand signal to generate clock signals;
• operating a charge pump connected to the self-timed clock circuit in a pump mode and then a precharge mode, the pump mode pumping charge to the substrate;
• and thereafter
• entering a quiescent state wherein the self-timed clock circuit is ready to respond to a subsequent demand signal,
• including continuing said operating steps to completion even if the demand signal terminates before said completion;
• and
• disregarding any demand signals subsequent to the first-received demand signal but before said completion.

A method of operating a charge pump for biasing the voltage of a substrate of an integrated circuit comprising the steps of:

• a monitor circuit for providing a demand signal indicative that adjustment of the substrate voltage is in demand;
• a clock circuit coupled to receive the demand signal for generating a full set of clock signals including first clock signals for use by a charge pump to pump charge and second clock signals for precharging the charge pump;
• the clock circuit being configured to complete said generating of a full set of clock signals despite any termination of the demand signal;
• a charge pump responsively coupled to the clock circuit;
• and
• the charge pump being effective to pump charge to the substrate;
• the charge pump being precharge by the second clock signals;
• whereby the generation of a full set of clock signals permits the charge pump to pump and precharge fully in response to receipt of a demand signal despite any change in the demand signal during said full cycle of clock signals.