CLASS-E RADIO FREQUENCY POWER AMPLIFIER WITH FEEDBACK CONTROL

Abstract

A Class-E power amplifier includes a choke and a switch connected in series between a source of a supply voltage and circuit ground and connected to an inductively coupled coil. An output node of the amplifier is formed between choke and the switch and connected to a transmitter antenna. A shunt capacitor couples the amplifier's output node to the circuit ground. A feedback signal, indicating an intensity if the signal at the amplifier output node is used to vary the input signal to the Class-E power amplifier and thereby control operation of the switch.

Description

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram of a wireless transvascular platform, that includes external and internal components, for stimulating tissue inside a patient;

FIG. 2 is a schematic diagram of an exemplary implanted medical device with an external component containing a Class-E RF amplifier;

FIG. 3 is a detailed schematic diagram of the Class-E RF amplifier; and

FIG. 4 depicts waveforms for signals in the Class-E RF amplifier.

Claims

1. A Class-E radio frequency power amplifier that receives a radio frequency input signal and that drives a load, said Class-E radio frequency power amplifier comprising: a switch;a choke connected in series with the switch between a source of a supply voltage and circuit ground, with an amplifier output node being formed between choke and the switch and connected to the load,a shunt capacitor coupling the amplifier output node to the circuit ground; andan output sensor which produces a feedback signal indicating an intensity of a signal applied to the load, wherein the feedback signal is employed to vary the radio frequency input signal.

2. The Class-E radio frequency power amplifier as recited in claim 1 wherein the switch is selected from a group consisting of a semiconductor device and a MOSFET.

3. The Class-E radio frequency power amplifier as recited in claim 1 wherein the switch is a semiconductor device and the feedback signal is proportional to an induced voltage at the load.

4. The Class-E radio frequency power amplifier as recited in claim 1 wherein the output signal controls a duty cycle of the switch;

5. The Class-E radio frequency power amplifier as recited in claim 1 wherein the switch is a MOSFET that has a channel resistance and a peak current rating, wherein an arithmetic product of the channel resistance and a peak current rating is less than 3% of the supply voltage applied to the Class-E amplifier.

6. The Class-E radio frequency power amplifier as recited in claim 1 wherein the switch is rated to conduct a transient current level that is at least ten times a maximum level of a current that the switch is expected to conduct.

7. The Class-E radio frequency power amplifier as recited in claim 1 wherein the radio frequency input signal has an envelope defined by a control signal.

8. The Class-E radio frequency power amplifier as recited in claim 1 wherein the amplifier is a component of an MRI scanner.

9. The Class-E radio frequency power amplifier as recited in claim 1 wherein the amplifier supplies energy to a device implanted in an animal.

10. The Class-E radio frequency power amplifier as recited in claim 1 wherein the amplifier enables modulated data transmission with power amplification.

11. The Class-E radio frequency power amplifier as recited in claim 1 wherein the amplifier responds to rectangular pulses derived from non-linear manipulation of a sinusoidal envelope voltage.