Impedance multiplier

An electronic filter, comprising:

• a filter capacitor;
• a filter resistor having a value of resistance coupled to said filter capacitor;
• means coupled to said filter resistor for lowering a corner frequency of the filter;
• and
• wherein said means for lowering said corner frequency comprises means for multiplying said value of resistance by a multiplication factor;
• and
• wherein said means for multiplying comprises a first and a second voltage follower amplifier, each having an input and an output, and a first and a second scaling resistor, said filter resistor being coupled between said input of said first voltage follower amplifier and said output of said second voltage follower amplifier, said first and said second scaling resistors establishing a voltage division between said output of said first voltage follower amplifier and said input of said second voltage follower amplifier.

An electronic filter, comprising:

• a filter capacitor;
• a filter resistor having a value of resistance coupled to said filter capacitor;
• means coupled to said filter resistor for lowering a corner frequency of the filter;
• and
• wherein said means for lowering said corner frequency comprises means for multiplying said value of resistance by a multiplication factor;
• and
• wherein said means for multiplying comprises a first and a second scaling resistor, and wherein said multiplication factor is established by a ratio between said first and said second scaling resistor;
• and
• wherein said means for multiplying further comprises a first and a second voltage follower amplifier each having an input and an output, and wherein said filter resistor is coupled between said input of said first voltage follower amplifier and said output of said second voltage follower amplifier, and wherein said first scaling resistor is coupled between said output of said first voltage follower amplifier and said input of said second voltage follower amplifier, and wherein said second scaling resistor is coupled between said input of said second voltage follower amplifier and a signal source input.

An electronic filter, comprising:

• a filter capacitor;
• a filter resistor having a value of resistance coupled to said filter capacitor;
• means coupled to said filter resistor for lowering a corner frequency of the filter;
• and
• wherein said means for lowering said corner frequency comprises means for multiplying said value of resistance by a multiplication factor;
• and
• wherein said means for multiplying comprises a first voltage follower amplifier utilizing active negative feedback, and wherein said filter resistor is coupled in series with said active negative feedback.

An electronic filter, comprising:

• a filter capacitor;
• a filter resistor having a value of resistance coupled to said filter capacitor;
• means coupled to said filter resistor for lowering a corner frequency of the filter;
• and
• wherein said means for lowering said corner frequency comprises means for multiplying said value of resistance by a multiplication factor;
• and
• wherein said means for multiplying comprises a first voltage follower amplifier utilizing active negative feedback, and wherein said filter resistor is coupled in series with said active negative feedback;
• and
• wherein said active negative feedback is produced by a first and a second scaling resistor and a second voltage follower amplifier, said first scaling resistor coupling an output of said first voltage follower amplifier to an input of said second voltage follower amplifier, said second scaling resistor coupled to said input of said second voltage follower amplifier and a signal source input, and wherein an output of said second voltage follower resistor is coupled through said filter resistor to an input of said first voltage follower amplifier.

A step-down switching regulator, comprising:

• a first and a second voltage follower amplifier, each having an input and an output;
• a first resistor coupled between said output of said first amplifier and said input of said second amplifier;
• a second resistor coupled to said input of said second amplifier and to an external source of switching pulses;
• a controlled switch having an input coupled to an external source of a signal to be regulated, an output, and a control terminal coupled to said output of said second amplifier;
• an inductor coupled to said input of said first amplifier and to said output of said controlled switch;
• and
• a filter capacitor coupled between said input of said first amplifier and a circuit common point;
• and
• wherein said input of said first amplifier forms an output terminal for the step-down switching regulator.

A circuit for multiplying the value of an impedance to be multiplied, comprising:

• a first and a second voltage follower amplifier each having an input and an output;
• a first resistor coupled between said output of said first amplifier and said input of said second amplifier;
• a second resistor coupled between said input of said second amplifier and a circuit common point;
• and
• wherein the impedance to be multiplied is coupled between said output of said second amplifier and said input of said first amplifier;
• and
• wherein said second amplifier provides active negative feedback to said first amplifier whereby the circuit multiplies the impedance to be multiplied by a multiplication factor equal to unity plus a ratio of said second resistor to said first resistor.