Phase-Controlled UWB Pulse Generator Using a Switched LC Oscillator
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Solution Overview
Problem
Existing UWB pulse generators struggle to implement binary phase-shift keying and effectively control the spectrum of transmitted pulses, especially at higher frequencies like 8 GHz, due to limitations in digital filter precision and switching times of digital circuit transistors, and lack efficient phase modulation capabilities.
Innovation Solution
A UWB pulse generator with a switched LC oscillator architecture that includes a phase control circuit to initiate oscillations with a defined phase and control the supply current, using two current-injecting branches to unbalance the differential pair and impose a specific phase for the pulse initiation, along with a current-switching circuit to manage the pulse duration and amplitude.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fully digital transmitter architectures are used to control the spectrum and reduce side lobes, then spectral control precision is improved, but device complexity and manufacturing cost increase due to required high-speed digital circuit technologies
Solution Approach 1:
The patent replaces complex digital filter architectures with a switched LC oscillator architecture that uses analog resonant circuits and timing-controlled switching. This substitution achieves spectral control through the natural resonance properties of LC circuits rather than through complex digital signal processing, thereby reducing device complexity while maintaining spectral control precision.
2Speed
If digital circuit transistors are used for switching at 8 GHz center frequency, then switching speed is improved, but manufacturing precision requirements become excessively high and cost increases
Solution Approach 1:
The patent changes the operating parameters by using LC resonant circuits operating at their natural resonant frequency rather than relying on digital transistor switching at 8 GHz. The LC oscillator architecture allows the circuit to operate at high frequencies through resonant oscillation rather than through high-speed digital switching, thereby achieving the required speed without excessive manufacturing precision requirements.
3Ease of manufacture
If switched LC oscillator architecture is used for integration in standard technologies, then ease of manufacture is improved, but phase modulation capability deteriorates due to random oscillation initiation
Solution Approach 1:
The patent applies preliminary action by using a startup circuit that pre-charges specific capacitors before the oscillation cycle begins. This pre-charging establishes a predetermined voltage state that determines the phase of oscillation initiation. By controlling the initial charge state of the capacitors in the LC oscillator, the phase of the generated pulse can be precisely controlled, enabling phase modulation while maintaining ease of manufacture in standard technologies.
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
Enables simple implementation of binary phase-shift keying while minimizing phase errors and controlling the spectrum, allowing for efficient operation at higher frequencies with reduced technological mismatches and lower power consumption.
Implementation Method 1
a load composed of an LC circuit, resonating at the carrier frequency to be transmitted
Data Source
AI summary
An ultra-wideband pulse generator for radio communication with phase modulation at frequencies of multiple gigahertz comprises an oscillator formed by a pair of intersecting differential branches that have two outputs connected to an LC resonant load. The transmission of a UWB pulse is caused by the application of a supply current to the differential pair over a few nanoseconds. Two current-injecting branches are respectively connected to the outputs S and S′. The control of phase modulation consists in applying an injection current to a single branch to unbalance the differential pair at the start of the generation of the UWB pulse. Depending on the side from which the injection current is applied, the oscillation at the carrier frequency will initiate with one phase or an opposite phase.