PWM RF Circuit Using Phase-Switched Impedance Matching
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Solution Overview
Problem
Existing impedance matching networks, particularly tunable impedance matching networks (TMNs), face challenges in achieving accurate and dynamically adjustable pulse width modulation (PWM) waveforms for high-frequency applications, especially in high power systems, due to the need for high bias voltages and limited tuning resolution in analog and digital TMNs.
Innovation Solution
A phase-switched tunable impedance matching network (PS-TMN) and phase-switched impedance modulation amplifier (PSIM) using phase-shifting elements to generate PWM waveforms with dynamically controlled pulse width and phase shift, allowing fine resolution and efficient operation at high power levels without high bias voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If analog TMNs are used to achieve fast and accurate impedance matching over a wide range, then high bias voltages are required to operate at high power levels
Solution Approach 1:
The patent replaces analog varactor diodes with digitally controlled switches (transistors Q1-Q4) to generate PWM signals for impedance matching. This substitution eliminates the need for high bias voltages required by analog TMNs while maintaining fast and accurate impedance matching capability through digital control of the reactive elements.
Solution Approach 2:
The patent changes the control parameter from continuous analog voltage (requiring high bias) to digital PWM duty cycle control. By varying the duty cycle of the PWM signal generated by the phase-shifting circuit, the effective impedance is adjusted without requiring high bias voltages, thus resolving the contradiction between matching accuracy and power consumption.
2Use of energy by moving object
If digital TMNs are used to reduce bias voltage requirements, then limited tuning resolution and accuracy are achieved
Solution Approach 1:
The patent employs periodic PWM signaling with variable duty cycles to achieve continuous impedance tuning. The phase-shifting circuit generates PWM signals that periodically switch the reactive elements, and by varying the duty cycle within each period, fine-tuning resolution is achieved without requiring numerous discrete digital switches, thus maintaining low power consumption while improving tuning accuracy.
Solution Approach 2:
The patent introduces dynamic PWM duty cycle control to enable continuous impedance adjustment. Instead of static digital switching with limited resolution, the dynamic variation of PWM duty cycle provides fine-tuning capability, allowing the system to achieve high tuning resolution while maintaining the low power consumption advantage of digital control.
3Measurement precision
If the number of digital switches is increased to achieve fine-tuning resolution, then device complexity increases
Solution Approach 1:
The patent replaces multiple digital switches with a phase-shifting circuit that generates PWM signals. This substitution reduces device complexity by eliminating the need for numerous digital switches while achieving fine-tuning resolution through PWM duty cycle control. The phase-shifting circuit uses fewer components (transistors Q1-Q4, capacitors C1-C2, resistors R1-R2) to provide continuous tuning capability.
Solution Approach 2:
The phase-shifting circuit serves multiple functions: it generates PWM signals, provides phase control, and enables fine-tuning resolution through duty cycle variation. This multi-functional approach replaces what would otherwise require multiple separate digital switches, reducing overall device complexity while maintaining high tuning resolution capability.
Data Source
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AI summary
Described are concepts, systems, circuits and techniques directed toward methods and apparatus for generating one or more pulse width modulated (PWM) waveforms with the ability to dynamically control pulse width and phase with respect to a reference signal.