Carrier-Controlled Differential Demodulator for Low-Power AM Signals
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current demodulators, especially discrete-time analog demodulators, are complex and unsuitable for applications requiring low power consumption and small dimensions, such as microelectromechanical gyroscopes, due to their intricate design and synchronization requirements.
Innovation Solution
A fully differential demodulator with variable gain, utilizing a variable gain amplifier stage and a gain-control stage that adjusts gain based on a sinusoid of the carrier frequency, coupled with a controllable capacitance network and a sign-inverting circuit, to demodulate signals efficiently without the need for multiple operational amplifiers or complex synchronization circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional demodulators use multiple operational amplifiers, filters and synchronization circuits, then demodulation accuracy is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple demodulation functions into a single operational amplifier by using a variable gain amplifier configuration where the gain is controlled by a sinusoidal signal at the carrier frequency. This merging approach eliminates the need for separate multipliers, filters and synchronization circuits, achieving accurate demodulation with reduced circuit complexity
Solution Approach 2:
The variable gain amplifier stage serves multiple functions simultaneously: it acts as both an amplifier and a demodulator by varying its gain according to the carrier signal. The single operational amplifier performs amplification, signal mixing, and filtering functions that traditionally required separate dedicated circuits
2Measurement precision
If discrete-time analog demodulators use large number of timing signals, then synchronization accuracy is improved, but ease of operation deteriorates
Solution Approach 1:
The demodulator uses the carrier signal itself to control the gain of the amplifier, eliminating the need for external timing signals and synchronization circuits. The system serves itself by using the input carrier signal to automatically synchronize and demodulate the amplitude-modulated signal, greatly simplifying operation
3Measurement precision
If traditional demodulators use multiple circuit components, then demodulation performance is improved, but use of energy increases
Solution Approach 1:
By merging multiple circuit components into a single variable gain amplifier stage, the patent reduces the total number of active elements that consume power. The single operational amplifier with dynamically controlled gain replaces multiple amplifiers, filters and synchronizers, thereby reducing overall power consumption while maintaining demodulation performance
4Measurement precision
If conventional demodulators use complex synchronization circuits, then signal recovery accuracy is improved, but volume of device increases
Solution Approach 1:
The patent extracts and eliminates the complex synchronization circuits from the demodulator design by using the variable gain approach. The carrier signal directly controls the amplifier gain without requiring separate synchronization hardware, removing unnecessary components and reducing device volume while maintaining accurate signal recovery
Data Source
AI summary
A demodulator includes input terminals, for receiving an input signal, and an amplifier stage having a gain. The input signal is amplitude-modulated and is defined by a carrier signal at a carrier frequency and by a modulating signal. The demodulator includes, moreover, a gain-control stage, coupled to the amplifier stage for varying the gain of the amplifier stage according to a sinusoid of a frequency equal to the carrier frequency, on the basis of the carrier signal.