Amplifier circuit with reduced DC power related turn-on and turn-off transients

An amplifier circuit for operating with a single power supply, comprising:

• at least one current drawing component having a shutdown mode of operation, the shutdown mode of operation being selectable by a chip shutdown control signal;
• a reference generator including a capacitor for biasing between a power supply voltage and a circuit ground and configured to provide first and second reference voltages having values between the power supply voltage and the circuit ground, wherein the first reference voltage is initially at an initial reference value and subsequently moves toward a final reference value, the second reference voltage being at a potential between the initial reference value and the final reference value;
• a controller, coupled to the reference generator, for receiving the first and second reference voltages and configured to provide a control signal based on a comparison of the first and second reference voltages;
• and
• a delay mechanism configured to receive the control signal and to output the chip shutdown control signal substantially equal in state to but delayed in time from the control signal from the controller, wherein
• a turn-off event causes the first reference voltage to move from the initial reference value toward the final reference value causing the controller to generate the control signal, and further wherein the delay mechanism outputs the chip shutdown control signal.

A method of amplifying a signal using a single power supply and a controllable gain, comprising:

• providing an output signal from an amplifier, the amplifier selectively operating in either a first mode or a second mode;
• comparing a first reference voltage having a moving value between a power supply voltage and a circuit ground with a second reference voltage having a fixed value;
• based on the comparison, determining that the first reference voltage has moved past the second reference voltage;
• in response to determining that the first reference voltage has moved past the second reference voltage, generating a control signal;
• delaying the control signal by a predetermined time;
• and
• providing the delayed control signal to the amplifier wherein the amplifier switches from its first mode of operation and its second operating in response to the delayed control signal.

An apparatus for amplifying a signal using a single power supply and a controllable gain, comprising:

• means for providing an output signal using an amplifier, the amplifier being selectively operable in either a first mode or a second mode;
• means for compiling a first reference voltage having a moving value between a power supply voltage and a circuit ground with a second reference voltage having a fixed value;
• means for determining, based on the comparison, that the first reference voltage has moved past the second reference voltage;
• means for generating, in response to determining that the first reference voltage has moved past the second reference voltage, a control signal;
• means for delaying the control signal by a predetermined time;
• and
• means for providing the delayed control signal to the amplifier wherein the amplifier switches from its first mode of operation and its second operating in response to the delayed control signal.