Current amplifiers

A method for operating a current amplifier having an input lead for receiving an input current to be amplified and an output terminal for providing an output current as a function of said input current, first and second supply voltage leads for receiving first and second supply voltages, and first and second transconductance amplifiers, each having a first differential input lead, a second differential input lead, and an output lead, said method comprising the steps of:

• providing an anti-shoot through circuit to apply a first set of signals as a function of said input current to said first differential input leads of said first and second transconductance amplifiers;
• providing drive signals from each of said output leads of said transconductance amplifiers to a respective one of a first set of transistors, thereby causing said first set of transistors to conduct current to said output terminal;
• providing feedback signals to one of said differential input leads of each of said transconductance amplifiers in response to said currents flowing in said first set of transistors, so that said output signals of each of said transconductance amplifiers are set to cause said currents flowing in said first set of transistors to have a first set of selected values;
• and
• providing said drive signals to a respective one of a second set of transistors, thereby causing a set of currents of second selected values to flow in said second set of transistors to said output terminal of a respective one of said transconductance amplifiers.

A voltage regulator comprising:

• a supply voltage lead;
• a ground lead;
• a charge pump for providing a pumped supply voltage greater than said supply voltage;
• an output terminal for providing an output voltage of a desired voltage level between the voltage levels of said supply voltage and ground;
• a differential amplifier including a first differential input lead receiving a reference voltage related to the desired output voltage, a second differential input lead for receiving a voltage related to the output voltage appearing on said output terminal, and an output lead for providing a control signal for controlling the output voltage on said output lead;
• and
• a current amplifier comprising:
• an input lead coupled to said output lead of said differential amplifier;
• an output terminal coupled to said output terminal of said voltage regulator;
• a transconductance amplifier powered by said pumped supply voltage, comprising:
• a first differential input lead coupled to said input lead;
• a second differential input lead;
• an output lead;
• a transistor having a base receiving a bias voltage, an emitter coupled to said supply voltage lead, a first collector coupled to said output lead of said transconductance amplifier, and a second collector formed as an outer concentric collector surrounding said first collector and said emitter;
• a current path coupled between said first collector and ground, said current path drawing current in response to said input current;
• and
• a current control circuit coupled to said second collector and said charge pump to provide current from said charge pump to said output lead of said transconductance amplifier in response to current from said second collector;
• a first resistor connected between said first differential input lead of said transconductance amplifier and said supply voltage lead;
• a second resistor connected between said second differential input lead of said transconductance amplifier and said supply voltage lead;
• a first transistor having a first current handling lead coupled to said second differential input lead of said transconductance amplifier, a second current handling lead connected to draw current through said first transistor, and a control lead coupled to said output lead of said transconductance amplifier;
• and
• a second transistor having a first current handling lead coupled to said supply voltage lead, a second current handling lead connected to said output terminal, and a control lead coupled to said output lead of said transconductance amplifier,
• wherein said transconductance amplifier drives said control terminals of one or both of said first and second transistors to a voltage level in excess of said supply voltage.