Inductively Coupled Transformer Tunable Impedance Match Network
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High power RF transistors face challenges in impedance matching due to deviations in component values from nominal values, leading to reduced efficiency and power output, and existing compensation techniques are costly and complex.
Innovation Solution
A packaged RF power transistor with an input match network that includes a transformer and a tuning capacitor, where the tuning capacitor's capacitance is adjustable based on DC voltage variations to compensate for deviations in component values, ensuring optimal impedance matching and gain across a defined frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a low-pass L-C-L network with discrete components is used for impedance matching, then the input impedance can be matched to a lower Q over a specific frequency range, but actual component values deviate from nominal values due to process variation, causing significant performance deviation and requiring costly corrective measures
Solution Approach 1:
The patent transforms the fixed discrete component values into continuously adjustable parameters. By converting the L-C-L network into an inductively coupled transformer with adjustable coupling coefficient (k) and turns ratio (Np:Ns), the system can dynamically adapt to component value deviations without requiring physical component changes or complex corrective circuits.
Solution Approach 2:
The invention introduces dynamic adjustability to the matching network through the variable coupling coefficient and turns ratio of the inductively coupled transformer. This allows the system to adapt in real-time to manufacturing variations, replacing the static discrete component approach with a dynamic parameter adjustment mechanism that compensates for process variations.
2Ease of manufacture
If nominal component values are used in the low-pass L-C-L network, then the design is simplified, but minor variations in component values have substantial impact on performance, leading to parts being discarded or requiring corrective measures
Solution Approach 1:
The inductively coupled transformer configuration enables the matching network to self-adjust and self-compensate for component variations. The adjustable coupling coefficient and turns ratio allow the system to automatically adapt to manufacturing tolerances without requiring external corrective measures or complex testing procedures, thereby maintaining both ease of manufacture and performance consistency.
3Power
If the match network is designed for a specific frequency range, then high gain is achieved at the desired operating frequency, but the improvement in impedance matching can only be achieved in a narrow frequency range
Solution Approach 1:
The inductively coupled transformer provides dynamic control over the matching characteristics through adjustable coupling coefficient and turns ratio. This enables the system to maintain optimal impedance matching across a broader frequency range compared to fixed discrete component networks, as the parameters can be adjusted to compensate for frequency deviations while maintaining high gain at the operating frequency.
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 solution effectively adjusts the electrical characteristics of the RF power transistor to maintain maximum gain at the center frequency, compensating for deviations in component values and improving device efficiency and yield while reducing production costs.
Implementation Method 1
an input match network that includes an inductively coupled transformer configured to block DC voltages between the RF input lead and the gate terminal and to propagate AC voltages in a defined frequency range from the RF input lead to the gate terminal
Implementation Method 2
A capacitance value of the tuning capacitor is adjustable based upon a variation in DC voltage applied to the RF input lead so as to compensate for the deviation between the nominal component values and the actual component values
Data Source
AI summary
A packaged RF power transistor includes an RF input lead, a DC gate bias lead, an RF power transistor comprising gate, source and drain terminals, and an input match network. The input match network includes a primary inductor electrically connected to the RF input lead, a secondary inductor electrically connected to the gate terminal and to the DC gate bias lead, and a tuning capacitor electrically connected to the RF input lead and physically disconnected from the gate terminal. The input match network is configured to block DC voltages between the RF input lead and the gate terminal and to propagate AC voltages in a defined frequency range from the RF input lead to the gate terminal. The tuning capacitor is configured to adjust a capacitance of the input match network based upon a variation in DC voltage applied to the RF input lead.