Variable-Gain Differential Demodulator for Low-Power Baseband Conversion
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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 demodulator with a variable gain amplifier stage and a gain control stage that modifies capacitance in response to the carrier frequency, using switched-capacitor circuits to simplify the demodulation process and reduce the number of operational amplifiers and synchronization circuits needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional discrete-time analog demodulators are used, then demodulation function is achieved, but device complexity increases and power consumption rises
Solution Approach 1:
The patent extracts and eliminates the complex multiplication circuitry and sophisticated synchronization circuits from the demodulator design. By removing these unnecessary components and replacing them with a simplified variable gain amplifier approach, the device complexity is reduced while maintaining the demodulation function, thereby also reducing power consumption.
Solution Approach 2:
The patent changes the operational parameter of the amplifier stage by varying its gain according to the carrier frequency. This parameter change enables the demodulator to achieve the desired signal processing function through gain modulation rather than through complex multiplication operations, simplifying the overall device structure and reducing power consumption.
2Device complexity
If traditional demodulator circuits are used, then signal demodulation is achieved, but overall dimensions increase
Solution Approach 1:
The patent merges the functions of multiple operational amplifiers and synchronization circuits into a single variable gain amplifier stage. By combining these separate functional blocks into one integrated circuit element that varies its gain according to the carrier frequency, the overall dimensions and component count are significantly reduced while maintaining demodulation capability.
Solution Approach 2:
The variable gain amplifier stage serves multiple functions simultaneously: it amplifies the input signal, performs demodulation through gain variation, and replaces the need for separate multiplication and synchronization circuits. This multi-functionality reduces the number of components required and decreases the overall device dimensions.
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
The solution enables the development of demodulators with reduced complexity, smaller size, and lower power consumption, making them suitable for applications like microelectromechanical gyroscopes by effectively bringing amplitude-modulated signals into baseband without the need for complex multiplication circuits.
Implementation Method 1
the gain control stage is coupled to at least one controllable capacitive network for modifying a variable capacitance with a periodic signal equal to the carrier frequency
Data Source
AI summary
A demodulator is provided for demodulating an amplitude-modulated input signal defined by a carrier signal having a carrier frequency modulated by a modulating signal, the demodulator including an amplifier stage having a gain and structured to receive the amplitude-modulated input signal, and a gain control stage coupled to the amplifier stage and configured to vary the gain of the amplifier stage according to the carrier frequency of the carrier signal.