Feed-forward control system with current estimator

A feed-forward control system, comprising:

• a circuit operating at a clock rate that produces an output voltage at an output node;
• and
• a feedback loop that further comprises:
• a differential transconductance amplifier that generates a first error signal at the clock rate based on a difference between a voltage that corresponds to a capacitor current estimate and a reference voltage;
• a capacitor current estimator that produces a voltage that corresponds to the capacitor current estimate, wherein the capacitor current estimator creates a voltage drop that equals or is proportional to a voltage drop across an output capacitor due to parasitic inductance and parasitic resistance of the output capacitor;
• and
• a comparator that compares the first error signal to the voltage that corresponds to the capacitor current estimate to produce a second error signal to the circuit to adjust the output voltage.

A method for estimating capacitor current in a feed-forward control system, comprising:

• conducting a current through an output capacitor to ground;
• estimating a current magnitude for the current in an output current estimator and generating a voltage that corresponds to the estimated current magnitude, wherein the estimating comprises creating a voltage drop that equals or is proportional to a voltage drop across an output capacitor due to parasitic inductance and parasitic resistance of the output capacitor;
• comparing the voltage to a reference voltage;
• generating an error signal based on said comparing;
• and
• adjusting an output voltage based on the error signal.

A method for estimating capacitor current in a feed-forward control system, comprising:

• conducting a current through an output capacitor to ground;
• estimating a current magnitude for the current in an output current estimator and generating a voltage that corresponds to the estimated current magnitude by:
• creating a voltage drop across an estimator circuit capacitor that equals a voltage drop across the output capacitor;
• creating a voltage drop across an output of an RC network of the estimator circuit that equals or is proportional to a voltage drop across the output capacitor due to parasitic inductance and parasitic resistance of the output capacitor;
• and
• wherein:
• the voltage drop across the output of the RC network of the estimator circuit is proportional to current flowing through the parasitic inductance and resistance of the output capacitor;
• and
• the RC network of the estimator circuit has a time constant that is the same as the time constant of the output capacitor due to the parasitic inductance and capacitance.