Variable-Capacitance RF Phase Shifter for Stable Impedance
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Solution Overview
Problem
Radio frequency phase shifters in transmitters and receivers face inefficiencies when antenna elements are disabled, as they maintain constant impedance, leading to increased power consumption and reduced efficiency.
Innovation Solution
Incorporating a varactor at the signal input of a vector modulator to adjust capacitance and an additional cascode stage over the vector modulator to reduce output capacitance, allowing for higher gain at high frequencies and maintaining constant impedance across various phase settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If power is provided to maintain constant impedance when antenna elements are disabled, then impedance stability is improved, but energy efficiency deteriorates
Solution Approach 1:
The patent implements dynamic impedance matching by making the input capacitance variable through a varactor diode controlled by a capacitance control signal. This allows the impedance to adapt dynamically to different operating conditions (enabled/disabled antenna elements) rather than maintaining a fixed constant impedance, thereby eliminating the need for continuous power consumption to maintain impedance stability.
Solution Approach 2:
The patent changes the capacitance parameter of the input matching network by incorporating a varactor diode whose capacitance can be adjusted via a control signal. This parameter change enables the system to optimize impedance matching for different operational states without requiring continuous power delivery, thus improving energy efficiency while maintaining impedance stability when needed.
2Use of energy by moving object
If a varactor is added to adjust capacitance, then energy efficiency is improved, but device complexity increases
Solution Approach 1:
The varactor diode serves multiple functions simultaneously: it adjusts the input capacitance for impedance matching, enables programmable power modes, and facilitates efficient disabling of antenna elements. This multi-functionality justifies the added component by providing several benefits from a single element, thereby mitigating the increase in device complexity.
Solution Approach 2:
The varactor diode is controlled by a capacitance control signal that automatically adjusts the input capacitance based on the operational state of the antenna elements. This self-adjusting mechanism reduces the need for external intervention or complex control circuits, allowing the system to optimize its own performance with minimal additional complexity.
3Speed
If cascode is stacked over vector modulator to reduce output capacitance, then gain at high frequencies is improved, but device complexity increases
Solution Approach 1:
The patent adds a cascode stage (an additional dimensional layer to the amplifier structure) to address the frequency response limitation. This dimensional change in the circuit architecture provides the benefit of reduced output capacitance and improved high-frequency gain, with the complexity increase being a necessary trade-off for achieving the desired frequency performance.
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 enhances efficiency and gain in radio frequency phase shifters, particularly at high frequencies, while maintaining constant impedance, thus improving overall performance in both transmitter and receiver applications.
Implementation Method 1
A varactor coupled across the first input and the second input of the amplification stage adjusts a capacitance between the first input and the second input in response to a capacitance control signal
Data Source
AI summary
Aspects of the disclosure relate to a radio frequency phase shifter. An example includes an amplification stage to produce an amplified voltage, the amplification stage having a first amplifier with a first input coupled to a first output of a hybrid coupler and a second amplifier with a complementary second input coupled to a complementary second output of the hybrid coupler. A vector modulation stage coupled to the amplification stage receives the amplified voltage and produces a modulated vector, the vector modulation stage has an in-phase section and a quadrature section to control the phase of the modulated vector in response to a phase control signal. A varactor coupled across the first input and the second input of the amplification stage adjusts the capacitance between the first input and the second input in response to a capacitance control signal.