R. F. power amplifier

• US 4,743,858 A
• Filed: 06/20/1986
• Issued: 05/10/1988
• Est. Priority Date: 06/26/1985
• Status: Expired due to Fees

• Current Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Original Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Inventors: Everard, Jeremy K. A.
• Primary Examiner(s): Laroche, Eugene R.
• Assistant Examiner(s): Mottola, Steven J.
• Application Number:
  US06/876,543
• Time in Patent Office: 690 Days
• Field of Search: 330/10, 330/207 A, 330/251
• US Class Current: 330/10
• CPC Class Codes: H03F 3/2176 Class E amplifiers

Abstract

An r.f. power amplifier, typically a high efficiency, class E amplifier in which a reactive load circuit (18) is connected to a semiconductor switching device (10), the load circuit being designed to have the required input load angle and loaded Q so that the voltage across the device (10) goes to zero with zero slope before it switches on and passes current, is provided with a step recovery diode (32) connected to the device (10) to limit the voltage swing across the device (10) with no significant loss of efficiency. This allows the voltage-handling capability required of the device to be reduced or the amplifier output power to be increased by increasing the supply voltage.

Claims

1. An r.f. power amplifier comprising a switching device having a pair of main electrodes, and a load network capable of adjusting the relative phase of the voltages across and the currents flowing between said main electrodes, wherein the amplifier comprises semiconductor means for limiting the peak voltage swing across said main electrodes by storing charge in response to charging of capacitance in parallel with said main electrodes attempting to drive the voltage across said main electrodes to above a predetermined value and releasing the stored charge in response to discharging of said capacitance subsequently attempting to reduce said voltage once again.

2. An amplifier as claimed in claim 1, wherein the load network is capable of adjusting said relative phase to obtain high efficiency.

3. An improved r.f. power amplifier of the type having a switching device and a load network capable of adjusting the relative phase of the voltages across and currents through the switching device, wherein the amplifier comprises semiconductor means for limiting the peak voltage swing across the switching device by storing charge during substantially the time period that the voltage is being limited and subsequently releasing the stored charge, and wherein the semiconductor means comprises a step recovery diode.

5. An amplifier as claimed in claim 3 wherein the diode is connected to a supply rail by way of a bias voltage supply.

4. An improved r.f. power amplifier of the type having a switching device and a load network capable of adjusting the relative phase of the voltages across and currents through the switching device, wherein the amplifier comprises semiconductor means for limiting the peak voltage swing across the switching device by storing charge during substantially the time period that the voltage is being limited and subsequently releasing the stored charge, and wherein the semiconductor means comprises a Schottky diode coupled to a bias supply comprising a load network including a capacitor and inductor coupled in parallel.