Carrier Path Phase Slope Circuit for Wider Doherty Bandwidth
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Solution Overview
Problem
Conventional Doherty amplifiers face a trade-off between low power bandwidth and full power bandwidth due to phase misalignment between the carrier and peaking input paths, limiting their wideband RF performance.
Innovation Solution
Incorporating phase slope adjustment circuitry, such as a constant-k bandpass filter with resonant LC cells, to align the phase of the carrier signal with the peaking signal at the output combining node, reducing frequency dispersion and improving full power bandwidth without affecting low power performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional Doherty amplifier design is used, then low power bandwidth is maintained, but full power bandwidth is limited due to phase misalignment
Solution Approach 1:
A phase adjustment network is introduced as an intermediary component between the power divider and the carrier amplifier. This network includes specific capacitor and inductor values (C1, C2, L1, L2, L3) that act as a mediator to correct the phase relationship between carrier and peaking signals, enabling both low power and full power bandwidth requirements to be satisfied simultaneously
2Adaptability or versatility
If frequency deviation between input paths is increased, then full power bandwidth may improve, but phase misalignment worsens
Solution Approach 1:
The phase adjustment network modifies the electrical parameters (capacitance and inductance values) of the carrier path to compensate for frequency-dependent phase deviations. By carefully selecting C1, C2, L1, L2, and L3 values, the network adjusts the phase characteristics across the frequency range, maintaining precise phase alignment despite frequency variations between 2 GHz and 2.5 GHz
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The phase slope adjustment circuitry enhances the full power bandwidth of Doherty amplifiers while maintaining low power performance, reducing output power ripple and improving wideband RF performance across a wider frequency range.
Implementation Method 1
the phase slope adjustment circuitry being configured to adjust a phase-dependent slope of a phase of the first signal
Implementation Method 2
phase slope adjustment circuitry, such as a constant-k bandpass filter with resonant LC cells
Implementation Method 3
a power divider coupled to the input and configured to divide an input signal received from the input into a first signal and a second signal
Implementation Method 4
a carrier amplifier configured to amplify the first signal to produce a first amplified signal and a peaking amplifier configured to amplify the second signal to produce a second amplified signal
Implementation Method 5
a combining node configured to combine first amplified signal and the second amplified signal to produce an output signal
Data Source
AI summary
An amplifier device having multiple amplification paths, such as a Doherty amplifier device, may include phase slope adjustment circuitry configured to adjust the frequency-dependent slope of the phase of an input carrier signal along a carrier path of the amplifier. By adjusting the phase slope of the input carrier signal in this way, the phase difference between carrier and peaking signals at an output combining node of the amplifier may be reduced, thereby reducing output power ripple of the amplifier. The phase slope adjustment circuitry may be a constant-k bandpass filter. The phase slope adjustment circuitry may have a zero-degree insertion phase at the center frequency of the amplifier. The phase slope adjustment circuitry may be implemented using surface mount inductors and capacitors.