In-Package Amplifier Bias Control Using Quiescent Current Estimation
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Solution Overview
Problem
Existing amplifier systems face challenges in efficiently biasing amplifiers due to manufacturing variations, often requiring complex external circuitry or current sensing elements that reduce efficiency and increase size, especially when trying to achieve a desired quiescent current.
Innovation Solution
A method is introduced where the bias voltage is adjusted within the amplifier device package by measuring the voltage difference between the output terminal and the physical output interface using individual conductive elements, allowing for the calculation of quiescent current and subsequent adjustment to achieve a target current without the need for external circuitry, utilizing high impedance nodes to minimize current flow and avoid voltage drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional external circuitry is used to measure and adjust quiescent current, then biasing accuracy is improved, but device complexity and size increase
Solution Approach 1:
The patent extracts the current measurement function from external circuitry and relocates it inside the amplifier package. A sense resistor is integrated within the package, and its voltage is measured by a control circuit inside the package, eliminating the need for external current sensing components while maintaining measurement accuracy.
Solution Approach 2:
The patent merges the current sensing function with the amplifier package itself. The sense resistor, control circuit, and amplifier are combined into a single integrated package, allowing quiescent current measurement and biasing adjustment to be performed internally without external components.
2Measurement precision
If current sensing elements are placed in series with the amplifier, then quiescent current measurement is improved, but amplifier efficiency decreases
Solution Approach 1:
The patent introduces a sense resistor as an intermediary element that has minimal impact on amplifier efficiency. The sense resistor is positioned to measure only the bias current path, not the main RF signal path, and its low resistance value minimizes power loss while providing accurate quiescent current measurement.
3Manufacturing precision
If bias voltage is adjusted using external circuitry, then quiescent current control is improved, but device size increases
Solution Approach 1:
The patent combines the bias voltage adjustment circuitry with the amplifier into a single integrated package. The control circuit that measures quiescent current and adjusts bias voltage is located inside the package, eliminating external adjustment components and reducing overall system size while maintaining control precision.
4Device complexity
If manufacturing variations are not compensated, then device simplicity is maintained, but amplifier performance consistency deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the control circuit continuously monitors the quiescent current through the sense resistor and automatically adjusts the bias voltage to maintain the desired operating point. This closed-loop feedback compensates for manufacturing variations and ensures consistent amplifier performance across different devices.
Solution Approach 2:
The amplifier package performs self-adjustment of its biasing conditions through the integrated control circuit. The system automatically measures its own quiescent current and adjusts its own bias voltage, eliminating the need for external calibration or manual adjustment while compensating for manufacturing variations.
Data Source
AI summary
Apparatus, systems, and fabrication methods are provided for biasing amplifier arrangements inside device packages to a target quiescent current. In one embodiment, an amplifier device has an output interface and includes an amplifier arrangement having an amplifier output and impedance matching circuitry coupled between the amplifier output and the output interface. A method for biasing the amplifier arrangement involves measuring or otherwise obtaining a voltage between the amplifier output and the output interface, determining an estimated quiescent current through the amplifier arrangement based on that voltage, and adjusting a bias voltage provided to the input of the amplifier arrangement based on a difference between the estimated quiescent current. In exemplary embodiments, the bias voltage is adjusted until the estimated quiescent current is substantially equal to a target quiescent current.