Class E/F switching power amplifiers

• US 6,724,255 B2
• Filed: 10/09/2001
• Issued: 04/20/2004
• Est. Priority Date: 10/10/2000
• Status: Expired due to Term

• Current Assignee: California Institute of Technology
• Original Assignee: California Institute of Technology
• Inventors: Hajimiri, Seyed-Ali, Aoki, Ichiro, Kee, Scott David, Rutledge, David B.
• Primary Examiner(s): NGUYEN, PATRICIA T
• Application Number:
  US09/974,557
• Publication Number:
  US 20020101284A1
• Time in Patent Office: 924 Days
• Field of Search: 330/207.A, 330/251, 330/292
• US Class Current: 330/251
• CPC Class Codes: H02M 7/48 using discharge tubes with control electrode or semiconductor devices with control electrode
• CPC Class Codes: H02M 7/537 using semiconductor devices only, e.g. single switched pulse inverters
• CPC Class Codes: H03F 3/217 Class D power amplifiers; Switching amplifiers
• CPC Class Codes: H03F 3/2173 of the bridge type
• CPC Class Codes: H03F 3/2176 Class E amplifiers

Abstract

The present invention discloses a new family of switching amplifier classes called “class E/F amplifiers.” These amplifiers are generally characterized by their use of the zero-voltage-switching (ZVS) phase correction technique to eliminate of the loss normally associated with the inherent capacitance of the switching device as utilized in class-E amplifiers, together with a load network for improved voltage and current wave-shaping by presenting class-F⁻¹ impedances at selected overtones and class-E impedances at the remaining overtones. The present invention discloses a several topologies and specific circuit implementations for achieving such performance.

Claims

1. A high efficiency switching power amplifier for amplifying a high frequency input signal having at least one fundamental frequency, and adapted to drive a load, comprising:

a high-speed active device that includes

a switching component that operates substantially as a switch and

a parasitic capacitance, C_out, in parallel wit the switching component; and

a hybrid class E/F load network connected to the active device, wherein the network is configured to present to the switching component, at al harmonic frequencies substantially present in at least one of the voltage and current waveforms f the active device,

(i) substantially inductive load at each fundamental frequency;

(ii) a substantially open circuit at a predetermined number, N_E, of even harmonic overtones for each fundamental frequency up to an N^th harmonic,

(iii) a substantially short circuit at a predetermined number, N_O, of odd harmonic overtones for each fundamental frequency up to an N^th harmonic, and

(iv) a substantially capacitive impedance load at the remaining harmonic overtones, up to an N^th harmonic,

where N≧

3 and 1≦

N_E+N_O≦

N−

2.

2. The amplifier of claim 1, wherein if N_E=1, then N_O>

0.

3. The amplifier of claim 1, wherein the load network includes a two port filter network having an input port and an output port, he input port being connected to the active device and the output port being connected to the load.

8. The amplifier of claim 1, wherein the load network is configured to provide wideband tuning of an input signal having a fundamental frequency range from f₁ to f₂ such that f₂≧

f≧

f₁, where f₂≦

3f₁.

9. The amplifier of claim 1, wherein the network is configured to present to the switching component, at all harmonic frequencies substantially present in at least one of the voltage and current waveforms of the active device,

(i) a substantially inductive load at each fundamental frequency;

(ii) a substantially open circuit at the 2^nd harmonic, and

(iii) a substantially capacitive impedance load at the remaining harmonic overtones, up to an N^th harmonic, where N≧

3.

10. The amplifier of claim 1, wherein the network is configured to present to the switching component, at all harmonic frequencies substantially present in at least one of the voltage and current waveforms of the active device

(i) a substantially inductive load at each fundamental frequency;

(ii) a substantially short circuit at the 3^rd harmonic, and

(iii) a substantially capacitive impedance load at the remaining harmonic overtones, up to an N^th harmonic,

where N≧

3.

11. The amplifier of claim 1, wherein the network is configured to present to the switching component, at all harmonic frequencies substantially present in at least one of the voltage and current waveforms of the active device

(i) a substantially inductive load at each fundamental frequency;

(ii) a substantially short circuit at the 3^rd harmonic,

(iii) a substantially open circuit at the 2^nd harmonic, and

(iv) a substantially capacitive impedance load at the remaining harmonic overtones, up to an N^th harmonic, where N≧

4.

12. The amplifier of claim 1, wherein the network is configured to present to the switching component, at all harmonic frequencies substantially present in at least one of the voltage and current waveforms of the active device

(i) a substantially inductive load at each fundamental frequency;

(ii) a substantially open circuit at the 4^th harmonic, and

(iii) a substantially capacitive impedance load at the remaining harmonic overtones, up to an N^th harmonic, where N≧

4.

13. The amplifier of claim 1, wherein the network is configured to present to the switching component, at all harmonic frequencies substantially present in at least one of the voltage and current waveforms of the active device

(i) a substantially inductive load at each fundamental frequency;

(ii) a substantially open circuit at the 2^nd and 4^th harmonics, and

(iii) a substantially capacitive impedance load at the remaining harmonic overtones, up to an N^th harmonic,

where N≧

4.

14. The amplifier of claim 1, wherein the network is configured to present to the switching component, at all harmonic frequencies substantially present in at least one of the voltage and current waveforms of the active device

(i) a substantially inductive load at each fundamental frequency;

(ii) a substantially short circuit at the 3^rd harmonic,

(iii) a substantially open circuit at the 4^th harmonic, and

(iv) a substantially capacitive impedance load at the remaining harmonic overtones, up to an N^th harmonic, where N≧

4.

15. The amplifier of claim 1, wherein the network is configured to present to the switching component, at all harmonic frequencies substantially present in at least one of the voltage and current waveforms of the active device

(i) a substantially inductive load at each fundamental frequency;

(ii) a substantially short circuit at the 3^rd harmonic,

(iii) a substantially open circuit at the 2^nd and 4^th harmonics, and

(iv) a substantially capacitive impedance load at the remaining harmonic overtones, up to an N^th harmonic,

where N≧

5.

16. The amplifier of claim 1, wherein the network is configured to present to the switching component, at all harmonic frequencies substantially present in at least one of the voltage and current waveforms of the active device

(i) a substantially inductive load at each fundamental frequency;

(ii) a substantially short circuit at all odd harmonic overtones up to an N^th harmonic,

(iii) a substantially capacitive impedance load at the remaining harmonic overtones, up to an N^th harmonic,

where N≧

5.

17. The amplifier of claim 1, wherein the network is configured to present to the switching component, at all harmonic frequencies substantially present in at least one of the voltage and current waveforms of the active device

(i) a substantially inductive load at each fundamental frequency;

(ii) a substantially short circuit at all odd harmonic overtones up to an N^th harmonic,

(iii) a substantially open circuit at a predetermined number, N_E, of even harmonic overtones for each fundamental frequency up to an N^th harmonic,

(iv) a substantially capacitive impedance load at the remaining harmonic overtones, up to an N^th harmonic,

where N≧

5 and 0<

N_E≦

(N−

2)/2.

4. A high efficiency switching power amplifier for amplifying a high frequency input signal having at least one fundamental frequency, and adapted to drive a load, comprising:

a high-speed active device that includes

a switching component that operates substantially as a switch and

a parasitic capacitance, C_out, in parallel wit the switching component; and

a hybrid class E/F load network connected to the active device, wherein the hybrid class E/F load network is configured to present to the witching component

(i) a substantially inductive load at the fundamental frequency of operation,

(ii) a substantially open circuit at a predetermined number of even harmonic overtones of the fundamental frequency,

(iii) a substantially short circuit at a predetermined number of odd harmonic overtones of the fundamental frequency, and

(iv) a substantially capacitive impedance load at the remaining harmonic overtones.

5. A high efficiency switching power amplifier for amplifying a high frequency input signal having at least one fundamental frequency, f₀, and adapted to drive a load, comprising:

(a) a high-speed active device that includes

a switching component that operates substantially as a switch and

a parasitic capacitance, C_out, in parallel with the switching component; and

(b) a hybrid class B/F load network connected to the active device, wherein the network is configured to present to the switching component, at all harmonic frequencies that are substantially present in at least one of the voltage and current waveforms of the active device,

(i) a substantially inductive load at each fundamental frequency of operation that results in substantially zero-voltage-switching (ZVS) operation of the active device,

(ii) impedances substantially larger in magnitude than 1/(2π

fCs) a at a predetermined number, N_E, of e en harmonic overtones of each fundamental frequency,

(iii) impedances substantially smaller in magnitude than 1/(2π

fCs) at a predetermined number, N_O, of odd harmonic overtones of each fundamental frequency, and

(iv) an impedance substantially equal to 1/jω

Cs at the remaining harmonic overtones of each fundamental frequency,

wherein

C_s=C_out+C_added, where C_added≧

0, and

N_E≧

0, N_O≧

0, and the total number of tuned harmonic overtones, N_E+N_O, is at least one and less than the total number of harmonic frequencies substantially present in the active device'"'"'s at least one of voltage and current waveforms.

6. A high efficiency switching power amplifier for amplifying a high frequency input signal having at least one fundamental frequency and adapted to drive a load, comprising:

(a) a first high-speed active device that includes

a switching component that operates substantially as a switch and

a parasitic capacitance, C_out1, in parallel with the switching component,

(b) a second high-speed active device that include

a switching component that operates substantially as a switch and

a parasitic capacitance, C_out2, in parallel with the switching component, and

(c) a hybrid three-port class E/F load network having

(i) a first port connected to the first active device,

(ii) a second port connected to the second active device, and

(iii) a third port connected to the load,

such that when the first and second active devices are driven in a push-pull configuration, the network presents to the switching components of the active devices an effective input impedance that provides

(i) a substantially inductive load in series with the substantially resistive load at all fundamental frequencies;

(ii) a substantially open circuit at one or more even harmonics for each fundamental frequency up to an Nth harmonic,

(iii) a substantially short circuit at one or more odd harmonics for each fundamental frequency up to an Nth harmonic, and

(iv) a substantially capacitive impedance load at the remaining harmonic overtones, up to an Nth harmonic.

7. The amplifier of claim 6, further including a transformer connected to the outputs of the two active devices and the load such that the load is dc isolated from the outputs of the two devices via the transformer.

18. A method of amplifying an RF signal with a high speed active device a that includes a switching component that operates substantially as a switch and a parasitic capacitance, C_out, in parallel with the switching component, comprising:

amplifying the signal with a high speed active device;

tuning the amplified signal to provide a substantially inductive load to the active device at the fundamental frequency;

tuning the amplified signal to provide a substantially open circuit to the active device at selected even harmonic overtones;

tuning the amplified signal to provide a substantially short circuit to the active device at selected odd harmonic overtones; and

providing substantially capacitive loading to the active device for the non-selected harmonic overtones.