Ripple cancellation circuit for ultra-low-noise power supplies

A method for generating a direct voltage across load terminals, said method comprising the steps of:

• capacitor connected across the load terminals:
• integrating first current applied to a storage
• applying to an inductor a voltage including a direct component and a varying component, to thereby generate said first current, whereby said varying component of said first current, when integrated by said storage capacitor, produces unwanted variations in the load voltage;
• applying said voltage including a direct component and a varying component to a second inductive arrangement, for thereby producing a current surrogate including a varying component corresponding to said varying current component and lacking a component corresponding to said direct component;
• and
• coupling said current surrogate to said capacitor in such a manner that said current surrogate reduces the amplitude of said varying component of said first current.

A power supply, comprising:

• a source of voltage defining first and second terminals:
• a controlled switch including a first electrode coupled to said first terminal of said source of voltage and defining a second electrode, for recurrently coupling said voltage to said second electrode of said controlled switch;
• unidirectional current conducting means connected to said second electrode of said controlled switch and to said second terminal of said source of voltage, poled for nonconduction when said voltage is coupled to said second electrode of said controlled switch;
• a storage capacitor including a first electrode connected to said second terminal of said source of voltage and also including a second electrode common with a load terminal, for integrating current applied thereto for generating a load voltage;
• an inductor connected to said second electrode of said controlled switch and to said second electrode of said storage capacitor, for generating an inductor current in response to the voltage at said second electrode of said controlled switch, which inductor current includes direct and varying current components;
• a transformer including a secondary winding and also including a primary winding coupled across said inductor, for producing a voltage at said secondary winding related to the voltage across said inductor;
• a second inductive arrangement coupled to said secondary winding of said transformer, for producing a current surrogate having properties similar to said varying component of said inductor current;
• and
• a combining arrangement including a blocking capacitor coupled to said second inductive arrangement and to said storage capacitor, for adding said current surrogate to said inductor current flowing to said storage capacitor, in a manner such as to tend to cancel said time-varying component of said inductor current.

A power supply, comprising:

• a source of voltage defining first and second terminals:
• a controlled switch including a first electrode coupled to said first terminal of said source of voltage and defining a second electrode, for recurrently coupling said voltage to said second electrode of said controlled switch;
• unidirectional current conducting means connected to said second electrode of said controlled switch and to said second terminal of said source of voltage, poled for nonconduction when said voltage is coupled to said second electrode of said controlled switch;
• a storage capacitor including a first electrode connected to said second terminal of said source of voltage and also including a second electrode common with a load terminal, for integrating current applied thereto for generating a load voltage;
• an inductor connected to said second electrode of said controlled switch and to said second electrode of said storage capacitor, for generating an inductor current in response to the voltage at said second electrode of said controlled switch, which inductor current includes direct and varying current components;
• an inductive second winding loosely coupled to said inductor, said inductive second winding producing a current surrogate having properties similar to said varying component of said inductor current;
• and
• a combining arrangement including a blocking capacitor coupled to said second inductive winding and to said storage capacitor, for adding said current surrogate to said inductor current flowing to said storage capacitor, in a manner such as to tend to cancel said varying component of said inductor current.