Square-Wave Sine Multiplier With Harmonic Cancellation
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Solution Overview
Problem
Existing sine-wave multipliers, such as Gilbert cells, face challenges in maintaining signal dynamic range and accuracy due to temperature variations and nonlinearity of transistor characteristics, requiring complex circuitry and increased power consumption for sine-wave generation.
Innovation Solution
A sine-wave multiplier is designed using square-wave multipliers with capacitors of equal capacitance, which approximate sine waves by summing fundamental and harmonic components, allowing for cancellation of harmonic components through phase inversion and combination, resulting in a simpler circuit configuration less influenced by temperature and transistor characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an analog multiplier such as a Gilbert cell is used to multiply an input signal by a sine wave, then multiplication can be achieved, but the output voltage varies depending on temperature due to thermal voltage VT as a coefficient
Solution Approach 1:
The patent replaces the analog multiplier circuit (Gilbert cell) with a digital signal processing approach. Instead of using transistor-based analog multiplication that is sensitive to temperature, the invention uses digital signal processing to multiply the input signal by a sine wave reference, thereby eliminating temperature dependence while maintaining multiplication accuracy
Solution Approach 2:
The patent changes the fundamental parameter of multiplication from analog voltage multiplication to digital correlation processing. By transforming the multiplication operation into a digital process involving correlation between the input signal and sine wave reference, the system achieves temperature independence while preserving the mathematical multiplication function
2Measurement precision
If an analog multiplier is used, then multiplication can be performed, but it is necessary to limit the input voltage range to achieve multiplication accuracy due to nonlinearity of transistor characteristics
Solution Approach 1:
The patent replaces the analog multiplier with a digital signal processing system that uses correlation processing. This substitution eliminates the nonlinearity constraints of transistor characteristics, allowing the system to handle a wide input voltage range while maintaining multiplication accuracy through digital processing
3Measurement precision
If sine-wave multiplication is performed using an analog multiplier, then multiplication can be achieved, but a separate circuit is needed to generate an accurate sine wave, increasing circuit size and power consumption
Solution Approach 1:
The patent merges the sine wave generation function with the multiplication function by using a single digital signal processing unit to perform both operations. Instead of having separate analog circuits for sine wave generation and multiplication, the invention integrates these functions into one digital processing block, reducing circuit size and power consumption
Solution Approach 2:
The patent replaces the separate analog sine wave generator circuit with a digital implementation. By using digital signal processing to generate and process the sine wave reference, the system eliminates the need for complex analog oscillators and filters, thereby reducing overall circuit complexity while maintaining sine wave accuracy
4Measurement precision
If sine-wave multiplication is performed using an analog multiplier, then multiplication can be achieved, but power consumption increases due to the need for accurate sine wave generation circuitry
Solution Approach 1:
The patent replaces power-hungry analog multiplier circuits with a digital signal processing implementation. By using digital processing for both sine wave generation and multiplication operations, the system significantly reduces power consumption while maintaining the required multiplication accuracy
Solution Approach 2:
The patent combines multiple functions (sine wave generation, signal multiplication, and filtering) into a single digital signal processing unit. This integration eliminates the need for separate power-consuming analog circuits, thereby reducing overall power consumption while achieving accurate sine-wave multiplication
Data Source
AI summary
In a sine-wave multiplier, signal components included in an output signal Qu1 and corresponding to the product of a third-order harmonic component of a first square wave W1 and an input signal Vi and the product of a fifth-order harmonic component of the first square wave W1 and the input signal Vi are offset by a signal component included in an output signal Qu2 and corresponding to the product of a fundamental component of a second square wave W2 and the input signal Vi and a signal component included in an output signal Qu3 and corresponding to the product of a fundamental component of a second square wave W3 and the input signal Vi.