Amplifier circuit with reduced DC power related transients

A method of operating an amplifier circuit for amplifying a signal while using a single power supply and a selectively variable reference voltage for reducing turn-on transients, said method comprising the steps of:

• biasing a first amplifier between a power supply voltage and a circuit ground;
• receiving a first input signal and a reference voltage having a selectively variable magnitude;
• generating a first output signal with a magnitude which varies in relation to and is approximately equal to a sum of said reference voltage and a selected multiple of said first input signal;
• and
• generating said reference voltage, wherein during a first time period said reference voltage magnitude changes linearly from approximately said circuit ground toward a fixed reference voltage magnitude, and during a second time period subsequent to said first time period said reference voltage remains at said fixed reference voltage magnitude.

An apparatus including an amplifier circuit for operating with a single power supply and a selectively variable reference voltage for reducing turn-on transients, said amplifier circuit comprising:

• a first amplifier for biasing between a power supply voltage and a circuit ground, receiving a reference voltage having a selectively variable magnitude and receiving a first input signal and in accordance therewith providing a first output signal which is approximately equal to a sum of said reference voltage and a selected multiple of said first input signal;
• and
• a reference generator, coupled to said first amplifier, for providing said reference voltage, wherein during a first time period said reference voltage magnitude changes linearly from approximately said circuit ground toward a fixed reference voltage magnitude, and during a second time period subsequent to said first time period said reference voltage remains at said fixed reference voltage magnitude;
• wherein said first amplifier has a gain associated therewith which is controlled by a control signal, and wherein said first amplifier gain, in accordance with said control signal, causes said selected multiple of said first input signal to be approximately zero during said first time period.

An apparatus including an amplifier circuit for operating with a single power supply and a selectively variable reference voltage for reducing turn-on transients, said amplifier circuit comprising:

• a first amplifier for biasing between a power supply voltage and a circuit ground, receiving a reference voltage having a selectively variable magnitude and receiving a first input signal and in accordance therewith providing a first output signal which is approximately equal to a sum of said reference voltage and a selected multiple of said first input signal;
• and
• a reference generator, coupled to said first amplifier, for providing said reference voltage, wherein during a first time period said reference voltage magnitude changes linearly from approximately said circuit ground toward a fixed reference voltage magnitude, and during a second time period subsequent to said first time period said reference voltage remains at said fixed reference voltage magnitude;
• wherein said first amplifier is further for operating in a first plurality of modes of operation for providing said first output signal, and wherein said first plurality of modes of operation is controlled by a control signal such that during said first time period said reception of said first input signal by said first amplifier is disabled and said selected multiple of said first input signal is approximately zero and further such that during said second time period said selected multiple of said first input signal is enabled to be non-zero.

An apparatus including an amplifier circuit for operating with a single power supply and a selectively variable reference voltage for reducing turn-on transients, said amplifier circuit comprising:

• a first amplifier for biasing between a power supply voltage and a circuit ground, receiving a reference voltage having a selectively variable magnitude and receiving a first input signal and in accordance therewith providing a first output signal which is approximately equal to a sum of said reference voltage and a selected multiple of said first input signal;
• and
• a reference generator, coupled to said first amplifier, for providing said reference voltage, wherein during a first time period said reference voltage magnitude changes linearly from approximately said circuit ground toward a fixed reference voltage magnitude, and during a second time period subsequent to said first time period said reference voltage remains at said fixed reference voltage magnitude;
• wherein said amplifier circuit further comprises a second amplifier, coupled to said first amplifier, for biasing between said power supply voltage and said circuit ground, receiving said reference voltage and receiving a second input signal and in accordance therewith providing a second output signal which is approximately equal in magnitude to said first output signal during said first time period and approximately equal in magnitude and inverse in phase to said first output signal during said second time period.

An apparatus including an amplifier circuit for operating with a single power supply and a selectively variable reference voltage for reducing turn-on transients, said amplifier circuit comprising:

• a first amplifier for biasing between a power supply voltage and a circuit ground, receiving a reference voltage having a selectively variable magnitude and receiving a first input signal and in accordance therewith providing a first output signal which is approximately equal to a sum of said reference voltage and a selected multiple of said first input signal;
• and
• a reference generator, coupled to said first amplifier, for providing said reference voltage, wherein during a first time period said reference voltage magnitude changes linearly from approximately said circuit ground toward a fixed reference voltage magnitude, and during a second time period subsequent to said first time period said reference voltage remains at said fixed reference voltage magnitude;
• wherein said first amplifier is further for operating in a first plurality of modes of operation for providing said first output signal, and wherein said amplifier circuit further comprises a second amplifier, coupled to said first amplifier, for biasing between said power supply voltage and said circuit ground, operating in a second plurality of modes of operation and receiving a second input signal and in accordance therewith providing a second output signal which is approximately equal in magnitude to said first output signal during said first time period and approximately equal in magnitude and inverse in phase to said first output signal during said second time period, and further wherein said first and second pluralities of modes of operation are controlled by a control signal such that during said first time period said receptions of said first and second input signals by said first and second amplifiers, respectively, are disabled and said selected multiple of said first input signal is approximately zero and further such that during said second time period said selected multiple of said first input signal is enabled to be non-zero.

A method of operating an amplifier circuit for amplifying a signal while using a single power supply and a selectively variable reference voltage for reducing turn-on transients, said method comprising the steps of:

• biasing a first amplifier between a power supply voltage and a circuit ground;
• receiving a first input signal and a reference voltage having a selectively variable magnitude;
• generating a first output signal which is approximately equal to a sum of said reference voltage and a selected multiple of said first input signal;
• and
• generating said reference voltage, wherein during a first time period said reference voltage magnitude changes linearly from approximately said circuit ground toward a fixed reference voltage magnitude, and during a second time period subsequent to said first time period said reference voltage remains at said fixed reference voltage magnitude;
• wherein said first amplifier has a gain associated therewith which is controlled by a control signal, and wherein said step of generating a first output signal comprises controlling said first amplifier gain, in accordance with said control signal, so as to cause said selected multiple of said first input signal to be approximately zero during said first time period.

A method of operating an amplifier circuit for amplifying a signal while using a single power supply and a selectively variable reference voltage for reducing turn-on transients, said method comprising the steps of:

• biasing a first amplifier between a power supply voltage and a circuit ground;
• receiving a first input signal and a reference voltage having a selectively variable magnitude;
• generating a first output signal which is approximately equal to a sum of said reference voltage and a selected multiple of said first input signal;
• generating said reference voltage, wherein during a first time period said reference voltage magnitude changes linearly from approximately said circuit ground toward a fixed reference voltage magnitude, and during a second time period subsequent to said first time period said reference voltage remains at said fixed reference voltage magnitude;
• and
• operating said first amplifier in a first plurality of modes of operation for generating said first output signal, wherein said first plurality of modes of operation is controlled by a control signal such that during said first time period said reception of said first input signal by said first amplifier is disabled and said selected multiple of said first input signal is approximately zero and further such that during said second time period said selected multiple of said first input signal is enabled to be non-zero.

A method of operating an amplifier circuit for amplifying a signal while using a single power supply and a selectively variable reference voltage for reducing turn-on transients, said method comprising the steps of:

• biasing a first amplifier between a power supply voltage and a circuit ground;
• receiving a first input signal and a reference voltage having a selectively variable magnitude;
• generating a first output signal which is approximately equal to a sum of said reference voltage and a selected multiple of said first input signal;
• generating said reference voltage, wherein during a first time period said reference voltage magnitude changes linearly from approximately said circuit ground toward a fixed reference voltage magnitude, and during a second time period subsequent to said first time period said reference voltage remains at said fixed reference voltage magnitude;
• biasing a second amplifier between said power supply voltage and said circuit ground;
• receiving said reference voltage and a second input signal;
• and
• generating a second output signal which is approximately equal in magnitude to said first output signal during said first time period and approximately equal in magnitude and inverse in phase to said first output signal during said second time period.

A method of operating an amplifier circuit for amplifying a signal while using a single power supply and a selectively variable reference voltage for reducing turn-on transients, said method comprising the steps of:

• biasing a first amplifier between a power supply voltage and a circuit ground;
• receiving a first input signal and a reference voltage having a selectively variable magnitude;
• generating a first output signal which is approximately equal to a sum of said reference voltage and a selected multiple of said first input signal;
• and
• generating said reference voltage, wherein during a first time period said reference voltage magnitude changes linearly from approximately said circuit ground toward a fixed reference voltage magnitude, and during a second time period subsequent to said first time period said reference voltage remains at said fixed reference voltage magnitude;
• operating said first amplifier in a first plurality of modes of operation for generating said first output signal;
• biasing a second amplifier between said power supply voltage and said circuit ground;
• operating said second amplifier in a second plurality of modes of operation;
• and
• receiving a second input signal and in accordance therewith generating a second output signal which is approximately equal in magnitude to said first output signal during said first time period and approximately equal in magnitude and inverse in phase to said first output signal during said second time period;
• wherein said first and second pluralities of modes of operation are controlled by a control signal such that during said first time period said receptions of said first and second input signals by said first and second amplifiers, respectively, are disabled and said selected multiple of said first input signal is approximately zero and further such that during said second time period said selected multiple of said first input signal is enabled to be non-zero.