Dual mode power amplifier for analog and digital cellular telephones
First Claim
1. A dual-mode portable radiotelephone comprising:
- a power supply including;
a dc voltage source;
plural switches, connected to the dc voltage source, actuable in accordance with a drive signal to provide dc power at different voltage levels;
a capacitor connected to the switches such that the capacitor and the dc voltage source are alternately placed in parallel across a diode and in series depending on the actuation states of the switches said diode preventing discharge of the capacitor through the switches; and
an RF power amplifier connected to the power supply wherein the rf power amplifier operable to provide liner and nonlinear amplification of a modulated RF input signal depending on the voltage level of the dc power provided by the power supply, wherein the switches are complementary transistors oppositely biased by the drive signal, including an NPN bipolar transistor and an PNP bipolar transistor, the bases of the transistors being connected to the drive signal, the emitter of the PNP transistor being connected to the dc voltage source and the anode of the diode, and the cathode of the diode being connected to the collectors of both the transistors via the capacitor.
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Accused Products
Abstract
The present invention relates generally to RF power amplifiers for portable cellular radiotelephones, and more particularly, to dual-mode cellular radiotelephones. A power supply network enables the RF power amplifier in a dual-mode radiotelephone to operate with two separate modes: saturated and unsaturated. Switches in the power supply network, e.g. complementary transistors, are driven to a first set of logic states by a square wave which is synchronized with transmit time slots present in a TDMA frame structure to charge a capacitor from a battery. When the switches are then driven to a second set of logic states, the capacitor is placed in series with the battery to essentially double the supply voltage. When the radiotelephone operates in a digital mode, the increased supply voltage coincides with the transmit time slot and temporarily increases the saturation point of the RF power amplifier to permit linear amplification. When the radiotelephone operates in an analog mode, the switches are fixed at the first set of logic states. The resulting lower supply voltage lowers the saturation point of the RF power amplifier, causing it to operate in a nonlinear but more efficient mode.
61 Citations
29 Claims
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1. A dual-mode portable radiotelephone comprising:
a power supply including; a dc voltage source; plural switches, connected to the dc voltage source, actuable in accordance with a drive signal to provide dc power at different voltage levels; a capacitor connected to the switches such that the capacitor and the dc voltage source are alternately placed in parallel across a diode and in series depending on the actuation states of the switches said diode preventing discharge of the capacitor through the switches; and an RF power amplifier connected to the power supply wherein the rf power amplifier operable to provide liner and nonlinear amplification of a modulated RF input signal depending on the voltage level of the dc power provided by the power supply, wherein the switches are complementary transistors oppositely biased by the drive signal, including an NPN bipolar transistor and an PNP bipolar transistor, the bases of the transistors being connected to the drive signal, the emitter of the PNP transistor being connected to the dc voltage source and the anode of the diode, and the cathode of the diode being connected to the collectors of both the transistors via the capacitor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. (Amended) A radiotelephone comprising:
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a dual-mode power supply for providing dc power at a first voltage level in a first mode and a second voltage level in a second mode including; a dc voltage source; complementary bipolar junction transistors, connected to the dc voltage source, oppositely biased in accordance with a drive signal; and a capacitor connected to the transistors such that the capacitor and the dc voltage source are alternately placed in parallel across a diode and in series depending on the bias applied to the transistors; the drive signal for determining the mode of the power supply; an RF power amplifier connected to the power supply wherein the RF power amplifier provides nonlinear amplification of a modulated RF input signal in the first mode and linear amplification of the modulated RF input signal in the second mode, wherein the bases of the transistors are connected to the drive signal, the emitter of one of the transistors is connected to the dc voltage source and the anode of the diode, and the cathode of the diode is connected to the collectors of both the transistors via the capacitor. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A power supply for providing different voltage power to an RF power amplifier in a mobile radiotelephone comprising:
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a battery; complementary bipolar transistors oppositely biased by a drive signal having two logic states, with the bases of the transistors being connected to the drive signal, a capacitor connected between said transistors such that said capacitor and said battery are alternately placed in parallel across a diode when said drive signal is at a first logic state and in series when said drive signal is at a second logic state, wherein the emitter of one of the transistors is connected to the battery and the anode of the diode, the cathode of the diode is connected to the collectors of both transistors via the capacitor, a first voltage is generated by the power supply when the drive signal is at said first logic state, and a second voltage is generated by the power supply when the drive signal is at said second logic state. - View Dependent Claims (21, 22, 23)
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24. A dual-mode portable radiotelephone comprising:
a power supply including; plural dc voltage source; plural switches, connected to the dc voltage sources, actuable in accordance with a drive signal to provide dc power at different voltage levels; a capacitor connected to the switches such that the capacitor and one of the plural dc voltage sources are placed in parallel across a diode and both of the plural dc voltage sources and the capacitor are placed in series depending on the actuation states of the switches, the diode preventing discharge of the capacitor through the switches; and an RF power amplifier connected to the power supply wherein the RF power amplifier is operable to provide linear and nonlinear amplification of a modulated RF input signal depending on the voltage level of the dc power provided by the power supply. - View Dependent Claims (25)
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26. A power supply for providing different voltage power to an RF power amplifier in a mobile radiotelephone comprising:
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a first battery connected in series at a series node to a second battery; complementary switches alternately actuated by a drive signal, said drive signal having two logic states; and a capacitor connected between said switches such that said capacitor and one of the first and second batteries are placed in parallel across a diode when said drive signal is at a first logic state and the capacitor and said first and second batteries are placed in series when said drive signal is at a second logic state, said diode preventing discharge of said capacitor through said switches, wherein a first voltage is generated by the power supply when the drive signal is at said first logic state and a second voltage is generated by the power supply when the drive signal is at said second logic state. - View Dependent Claims (27, 28, 29)
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Specification