US 6,236,273 B1Granted

High efficiency power amplifier

AssigneePairgain Technologies, Inc.

InventorLanny L. Lewyn

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Abstract

A monolithic integrated circuit amplifier has a gain stage and a buffer stage. The buffer stage includes an output stage and two separate voltage supplies, the second of which has a greater magnitude than the first. Switching circuitry is included that is connected to the output stage via a regulator bus. When an output demand voltage is less than a switch-over threshold, current to the output stage is provided substantially entirely from the first voltage supply; when the output demand voltage is greater than the switch-over threshold, current to the output stage is provided substantially entirely from the second voltage supply. Collector voltage at the output stage can be maintained greater than the emitter voltage by a predetermined, substantially constant amount. Voltage headroom circuitry is preferably also included for setting a voltage headroom, that is, the lowest voltage constantly available at the second current terminal of the output transistor relative to the first current terminal of the output transistor.

Claims23

Dependent claims

A monolithic integrated circuit amplifier having an input signal and an output signal comprising:

a gain stage that has a gain stage output signal and has, as an input, the amplifier input signal;
a buffer stage producing an amplifier output signal and having, as its input signal, the gain stage output signal;
an output stage, included within the buffer stage and having at least a first power output transistor that has first and second current terminals and a current control terminal;
a first and second voltage supply, the second voltage supply having a relatively higher magnitude than the first;
a first power control circuit connected to both the first and second voltage supplies, and to the output stage through a regulator bus;
the first power control circuit including
a first switching means connected to the first voltage supply;
and
a second switching means connected to the second voltage supply;
outputs of the first and second switching means both being connected to the regulator bus;
in which:
when an output demand voltage is less than a predetermined switch-over threshold:
current to the output stage is provided substantially entirely from the first voltage supply via the first switching means;
the first switching means provides, via the regulator bus, a voltage at the second current terminal of the output transistor that is greater than the voltage at the first current terminal of the output transistor by a predetermined, substantially constant amount;
and
the voltage on the regulator bus itself blocks current output from the second switching means;
and
when the output demand voltage is greater than the switch-over threshold:
current to the output stage is provided substantially entirely from the second voltage supply, via the second switching means;
and
the second switching means provides, via the regulator bus, a voltage at the second current terminal of the output transistor that is greater than the voltage at the first current terminal of the output transistor by the predetermined, substantially constant amount;
and
the voltage on the regulator bus itself blocks current output from the first switching means.

20 more elements

A monolithic integrated circuit amplifier having an input signal and an output signal comprising:

a gain stage that has a gain stage output signal and has, as an input, the amplifier input signal;
a buffer stage producing an amplifier output signal and having, as its input signal, the gain stage output signal;
an output stage, included within the buffer stage;
a first and second voltage supply, the second voltage supply having a relatively higher magnitude than the first;
a first power control circuit connected to both the first and second voltage supplies, and to the output stage through a regulator bus;
the first power control circuit including:
a first switching means connected to the first voltage supply and having at least a first analog switching transistor that has first and second current terminals and a current control terminal;
the first switching means further including at least a first control transistor that has first and second current terminals and a current control terminal, the first current control terminal being connected to the control terminal of the first analog switching transistor, the second current control terminal being connected to the second voltage supply;
and
voltage clamping means for limiting the voltage between the current control terminal of the first control transistor and the first voltage supply;
a second switching means connected to the second voltage supply and including at least a second analog switching transistor that has first and second current terminals and a current control terminal;
the first current terminals of the first and second analog switching transistors both being connected to the regulator bus;
in which:
when an output demand voltage is less than a predetermined switch-over threshold, current to the output stage is provided substantially entirely from the first voltage supply via the first switching means and the regulator bus;
when the output demand voltage is greater than the switch-over threshold:
current to the output stage is provided substantially entirely from the second voltage supply, via the second switching means;
and
the voltage clamping means is provided for limiting a maximum voltage on the current control terminal of the first control transistor, for thereby limiting the maximum voltage on the current control terminal of the first analog switching transistor, and thereby also for substantially preventing the flow of reverse current through the first and second current terminals of the first analog switching transistor.

15 more elements

A monolithic integrated circuit amplifier having an input signal and an output signal comprising:

a gain stage that has a gain stage output signal and has, as an input, the amplifier input signal;
a buffer stage producing an amplifier output signal and having, as its input signal, the gain stage output signal;
an output stage, included within the buffer stage;
a first and second voltage supply, the second voltage supply having a relatively higher magnitude than the first;
a first power control circuit connected to both the first and second voltage supplies and to the output stage through a regulator bus;
the first power control circuit including:
a first switching means connected to the first voltage supply and having at least a first analog switching transistor that has first and second current terminals and a current control terminal, the first switching means further including at least a first control transistor that has first and second current terminals and a current control terminal, the second current terminal of the first control transistor being connected to the second voltage supply, and the first current terminal of the first control transistor being connected to the current control terminal of the first analog switching transistor;
and
a second switching means connected to the second voltage supply, having at least a second analog switching transistor that has first and second current terminals and a current control terminal;
in which:
the first current terminals of the first and second analog switching transistors are both connected to the regulator bus;
when an output demand voltage is less than a predetermined switch-over threshold, current to the output stage is provided substantially entirely from the first voltage supply, via the first switching means and the regulator bus;
and
when the output demand voltage is greater than the switch-over threshold, current to the output stage is provided substantially entirely from the second voltage supply, via the second switching means and the regulator bus.

11 more elements

Dependencies are inferred from the claim text.