Inductive Circuit Offset Bond Wires Magnetic Coupling
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Solution Overview
Problem
Doherty amplifiers face challenges in achieving compact size and high power efficiency due to limitations in LDMOS technology, such as high RF losses, variable input impedances, and restricted operational frequency bandwidth, which affect power gain and introduce amplitude and phase deviations, especially in applications like WCDMA systems.
Innovation Solution
An inductive circuit with offset bond wires and capacitive coupling is used to split input signals for main and peak amplifiers, mitigating magnetic coupling and maintaining a constant phase shift, thereby enhancing power division and isolation between ports across a wide frequency band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If LDMOS devices are used for Doherty amplifier MMIC, then high performance at low cost is achieved, but magnetic coupling factor is limited to about 0.38 due to bond wire spacing constraints
Solution Approach 1:
The patent transitions from planar bond wire arrangements to a three-dimensional configuration where bond wires are positioned at different heights (levels) above the substrate. This vertical dimensionality change enables stronger magnetic coupling without increasing lateral spacing, thereby improving the coupling factor while maintaining manufacturing feasibility with standard LDMOS processes.
Solution Approach 2:
The patent employs arched or curved bond wire trajectories instead of straight wire configurations. This curvature allows the wires to maintain optimal coupling distance along their length while accommodating the physical constraints of the substrate and connection points, thereby enhancing magnetic coupling efficiency without compromising manufacturing ease.
2Reliability
If bond wire spacing is reduced to increase magnetic coupling, then coupling factor improves, but manufacturing constraints are violated
Solution Approach 1:
By introducing a vertical dimension with bond wires at different elevation levels, the patent achieves strong magnetic coupling without requiring reduced lateral spacing. The vertical separation allows wires to be positioned closer in the horizontal plane while maintaining manufacturable spacing through z-axis differentiation.
Solution Approach 2:
The curved or arched wire paths enable the bond wires to approach each other more closely at critical coupling regions while maintaining acceptable spacing at connection points, thereby achieving enhanced coupling factor without violating manufacturing spacing constraints throughout the entire wire length.
3Use of energy by moving object
If variable input impedances are used in peak amplifier, then power efficiency is improved, but amplitude and phase deviation occurs depending on power level
Solution Approach 1:
The patent incorporates feedback mechanisms through the coupled inductive circuits that sense output conditions and adjust input impedance dynamically. This feedback loop compensates for amplitude and phase deviations by actively adjusting the input impedance to maintain stable output characteristics while preserving power efficiency benefits.
Solution Approach 2:
The patent employs variable input impedance networks that can dynamically adjust their electrical parameters (inductance, capacitance) based on operating conditions. This parameter adjustment capability allows the system to maintain optimal power efficiency across different power levels while compensating for amplitude and phase deviations through real-time impedance transformation.
4Adaptability or versatility
If operational frequency bandwidth is extended, then system versatility is improved, but RF signal loss increases
Solution Approach 1:
The patent employs dynamic impedance matching networks with frequency-adjustable components that adapt their characteristics across the operational bandwidth. This dynamic adjustment optimizes impedance matching at different frequencies, thereby extending usable bandwidth while minimizing RF signal loss through frequency-specific optimization.
Solution Approach 2:
The patent utilizes tunable inductors and capacitors whose electrical parameters can be adjusted to maintain optimal impedance transformation ratios across a wide frequency range. By changing these parameters dynamically or providing multiple fixed settings, the system achieves extended bandwidth operation with minimized RF losses at each frequency point.
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
This configuration achieves high power efficiency and extended operational frequency bandwidth while minimizing RF signal loss, enabling efficient power splitting and isolation between output ports, thus addressing the limitations of traditional Doherty amplifiers.
Implementation Method 1
the bond wires of the first inductive circuit are offset from the bond wire of the second inductive circuit to control magnetic coupling between the bond wires
Implementation Method 2
A capacitive circuit couples the terminal to the first output terminal, and another capacitive circuit couples the input terminal to the second output terminal
Implementation Method 3
An inductive circuit with offset bond wires and capacitive coupling is used to split input signals for main and peak amplifiers, mitigating magnetic coupling and maintaining a constant phase shift
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A bond wire circuit (100) includes at least three bond wires (110,120,130) arranged to split an input signal into two output signals. In connection with various example embodiments, bond wires (110,120,130) are arranged in a generally parallel manner to mitigate magnetic coupling and related issues for splitting an input signal and providing each of split signals to an amplifier. The bond wires (110,120,130) are connected by capacitive circuits that facilitate the splitting, and in some applications, additional capacitive (to ground/reference) and load circuits to further facilitate the splitting of the input signals for specific amplifier circuit implementations, and applications to various loads. In some implementations, the input signals are split in equal or arbitrary portions with frequency independent phase differences in a wide frequency band, with isolation between ports of the circuit.