High-Speed, High-Voltage GaN-Based Operational Amplifier
A high-speed, high-voltage gallium nitride based (GaN-based) operational amplifier (op amp) is disclosed. The combined high-speed, high-voltage capability allows the GaN-based op amp to serve as a dynamic power supply (DPS) for a radio frequency power amplifier (RFPA). When serving as a DPS for an RFPA, the GaN-based op amp is capable of supplying ampere-scale currents that accurately track rapidly-varying envelopes of non-constant envelope RF signals, thereby allowing the RFPA to convert high-bandwidth non-constant envelope RF signals to high RF output powers with high signal envelope accuracy.
1 - 10 . (canceled)
11 . A gallium nitride based (GaN-based) operational amplifier (op amp), comprising:
a first GaN-based level-shifter; and
a first differential amplifier coupled to said first GaN-based level-shifter, said first differential amplifier including first and second GaN-based transistors.
12 . The GaN-based op amp of claim 11 , wherein the first and second GaN-based transistors of said first differential amplifier comprise first and second aluminum gallium nitride/gallium nitride (AlGaN/GaN) high electron mobility transistors (GaN-HEMTs).
13 . The GaN-based op amp of claim 11 , wherein said first GaN-based level-shifter is configured to ratiometrically establish a direct current operating point for said first differential amplifier.
14 . The GaN-based op amp of claim 11 , wherein said first GaN-based level-shifter comprises third and fourth GaN-based transistors.
15 . The GaN-based op amp of claim 14 , wherein said third and fourth GaN-based transistors are configured as first and second source followers.
16 . The GaN-based op amp of claim 11 , wherein said first differential amplifier includes a GaN-based tail current source.
17 . The GaN-based op amp of claim 11 , further comprising:
a second differential amplifier including third and fourth GaN-based transistors; and
a second gallium nitride based (GaN-based) level-shifter configured between said first differential amplifier and said second differential amplifier.
18 . The GaN-based op amp of claim 17 , further comprising an output stage including a fifth GaN-based transistor.
19 . The GaN-based op amp of claim 18 , wherein said output stage is configured as a source follower.
20 . The GaN-based op amp of claim 18 , wherein said second differential amplifier is single-endedly and directly coupled to said output stage.
21 . An envelope following radio frequency power amplifier (RFPA) apparatus,
comprising:
a gallium nitride based (GaN-based) operational amplifier (op amp) configured to serve as a dynamic power supply (DPS); and
an RFPA configured to be powered by said DPS.
22 . The envelope following RFPA apparatus of claim 21 , wherein said RFPA comprises a switch-mode power amplifier.
23 . The envelope following RFPA apparatus of claim 21 , wherein said RFPA comprises a linear power amplifier.
24 . The envelope following RFPA apparatus of claim 21 , wherein said RFPA comprises a GaN-based RFPA.
25 . The envelope following RFPA apparatus of claim 24 , wherein said GaN-based op amp and said GaN-based RFPA are integrated in a single integrated circuit.