Doherty Amplifier Combiner Layout for Wider Bandwidth
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Solution Overview
Problem
Existing Doherty amplifier topologies face challenges in achieving bandwidth improvement while minimizing area consumption, particularly at lower frequencies like 1 GHz.
Innovation Solution
A Doherty amplifier design that includes a non-impedance-inverting connection between the main amplifier and the Doherty combiner, along with impedance inverting networks between the peak amplifier and the Doherty combiner, ensuring a 180-degree phase difference at the input ports of the Doherty combiner to enhance bandwidth without the need for an impedance inverter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an impedance inverter in the form of a 90 degrees transmission line is arranged in between the output of main amplifier and combining node, then impedance inversion is achieved, but the bandwidth of the amplifier is degraded
Solution Approach 1:
The patent inverts the conventional approach by removing the impedance inverter from the main amplifier path and placing it only in the peak amplifier path. This reversal maintains the necessary impedance inversion functionality while eliminating the bandwidth degradation caused by the 90-degree transmission line in the critical signal path.
Solution Approach 2:
The impedance inverter is extracted from the main amplifier path and placed only in the peak amplifier path. This extraction eliminates the bandwidth-limiting 90-degree transmission line from the main signal path while preserving impedance inversion where needed for the peak amplifier's class C operation.
2Adaptability or versatility
If coupler is used for combining signals from main amplifier and peak amplifier, then impedance transformation is achieved, but area consumption increases particularly for low frequencies
Solution Approach 1:
The patent extracts the impedance transformation function from a traditional coupler and implements it using transmission lines with specific characteristic impedances. This approach replaces the area-consuming coupler structure with more compact transmission line implementations, particularly beneficial for low frequency applications like 1 GHz.
Solution Approach 2:
The patent changes the design parameters by using transmission lines with specific characteristic impedances (Z1 and Z2) instead of a conventional coupler. By adjusting the characteristic impedances and electrical lengths of these transmission lines, the same impedance transformation function is achieved with reduced area consumption.
3Loss of energy
If multiple peak amplifiers are used to obtain multiple efficiency peaks under power back-off, then efficiency under power back-off is improved, but device complexity increases
Solution Approach 1:
The patent introduces dynamic control mechanisms that allow a single peak amplifier to operate in multiple modes, effectively creating multiple efficiency peaks under power back-off conditions. The dynamic adjustment of impedance transformation ratios and operating points enables one amplifier to replace multiple amplifiers, reducing complexity while maintaining the multiple-efficiency-peaks characteristic.
Data Source
AI summary
Example embodiments relate to Doherty amplifiers. One example Doherty amplifier includes a main amplifier and a peak amplifier. The Doherty amplifier also includes a Doherty splitter configured for: splitting an input signal into a main signal part and a peak signal part and providing the main signal part and the peak signal part to the main amplifier and the peak amplifier, respectively. Additionally, the Doherty amplifier includes a Doherty combiner having a first input port, a second input port, and an output port. Further, the Doherty amplifier includes a non-impedance-inverting connection between an output of the main amplifier and the first input port. In addition, the Doherty amplifier includes a first impedance inverting network arranged in between an output of the peak amplifier and the second input port. Yet further, the Doherty combiner includes a second impedance inverting network and a third impedance inverting network.