N-Way Doherty Amplifier Bias Network for Harmonic Impedance Control
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Solution Overview
Problem
Conventional Doherty amplifiers face inefficiencies in power consumption and amplification performance due to fixed configurations and inadequate harmonic impedance control, particularly when dealing with varying signal amplitudes and parasitic components.
Innovation Solution
An N-way Doherty amplifier configuration with a main amplifier and (N-1) peak amplifiers, where the number of active peak amplifiers changes based on signal amplitude, and a first bias network with an electrical length less than 90 degrees supplies DC bias voltage to control harmonic impedance and compensate for parasitic components, along with optional second bias networks for further harmonic control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a conventional Doherty amplifier with fixed configuration is used, then the circuit structure is simple, but power consumption efficiency deteriorates when dealing with varying signal amplitudes
Solution Approach 1:
The amplifier configuration dynamically changes the number of active peak amplifiers based on signal amplitude. When signal amplitude is low, only the main amplifier operates; when amplitude increases, peak amplifiers are progressively activated. This dynamic adaptation optimizes power consumption efficiency across varying signal conditions while managing circuit complexity through controlled configurability.
Solution Approach 2:
The system changes operational parameters by adjusting which amplifiers are active based on signal characteristics. The main amplifier operates continuously while peak amplifiers are switched on/off according to signal amplitude thresholds, changing the effective configuration parameters to maintain optimal efficiency across different operating conditions.
2Reliability
If a Doherty amplifier with multiple peak amplifiers is used, then amplification performance improves for varying power levels, but device complexity increases
Solution Approach 1:
The amplifier system is segmented into a main amplifier and multiple peak amplifiers that can be independently controlled. Each peak amplifier handles specific power level ranges, allowing the system to maintain high amplification performance across varying power levels while managing complexity through modular, selectively-activated segments rather than requiring all components to be simultaneously active.
3Reliability
If bias networks with standard electrical length are used, then DC bias voltage supply is straightforward, but harmonic impedance control and parasitic compensation are inadequate
Solution Approach 1:
The bias network's electrical length parameter is specifically changed to be less than 90 degrees, deviating from standard configurations. This parameter modification enables the bias network to simultaneously perform DC bias voltage supply and provide harmonic impedance control with parasitic compensation capabilities, achieving multiple functions through a modified single parameter rather than adding complex separate networks.
Data Source
AI summary
An amplifier has an N number of input networks connected to an input terminal to receive an input signal, a first amplifier to amplify one output signal from the N number of input networks, a (N−1) number of secondary amplifiers to amplify the remaining (N−1) number of output signals, except for the one output signal, from the N number of input networks, where the amplification order of the (N−1) number of secondary amplifiers is determined based on the power level of each output signal from the N number of input networks when the first amplifier is operational, an N number of output networks which are arranged, and a first bias network to supply a D.C. bias voltage to at least one of the N number of output networks. An electrical length of the first bias network is less than 90 degrees.