Digital Mixer Circuit for High-Precision Frequency Measurement
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Solution Overview
Problem
Existing technologies face challenges in accurately determining the frequency of signals, particularly in applications requiring high precision for function safety, temperature measurement, and communication protocols, where current methods lack the necessary accuracy and reliability.
Innovation Solution
A circuit is designed to determine signal frequency using an analog-to-digital converter, a digital mixer, a low-pass filter, and a measuring circuit that measures the period of a filtered signal to output a value differing from the frequency of a single bit binary signal by the inverse of the measured period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional frequency measurement methods are used, then the device complexity is low, but the measurement precision is insufficient for high-accuracy applications
Solution Approach 1:
The frequency measurement process is segmented into distinct functional stages: analog-to-digital conversion, digital mixing with reference signal, low-pass filtering, and period measurement. Each stage processes a specific aspect of the signal, breaking down the complex measurement task into manageable steps that collectively achieve high precision
Solution Approach 2:
A digital mixer is introduced as an intermediary component that combines the input signal with a reference signal at a known frequency. This mixing process generates sum and difference frequency components, allowing the measurement system to operate at lower frequencies where timing measurements are more accurate, thereby improving overall measurement precision without directly measuring the high-frequency signal
2Measurement precision
If high-precision frequency determination is implemented, then the measurement precision improves, but the device complexity increases due to multiple conversion and processing stages
Solution Approach 1:
The system replaces direct analog frequency measurement methods with a digital signal processing approach. By converting the analog signal to digital form and using digital mixing and filtering operations, the system achieves higher measurement precision while using standard integrated circuit components, effectively substituting complex analog measurement mechanisms with more manageable digital processing
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 circuit achieves precise frequency determination with sensitivities ranging from 3.28 us/0.1% to 32.8 us/ppm, enabling applications such as clock monitoring and temperature sensing with high accuracy.
Implementation Method 1
an analog to digital converter configured to convert the analog input signal to a digital input signal
Implementation Method 2
a digital mixer configured to generate a mixing result signal by mixing the digital input signal with a single bit binary signal having a reference frequency
Implementation Method 3
a low pass filter configured to generate a filtered signal by filtering the mixing result signal
Data Source
AI summary
According to various embodiments, a circuit for determining the frequency of a signal is described, comprising an input configured to receive an analog input signal, an analog to digital converter configured to convert the analog input signal to a digital input signal, a digital mixer configured to generate a mixing result signal by mixing the digital input signal with a single bit binary signal having a reference frequency, a low pass filter configured to generate a filtered signal by filtering the mixing result signal, a measuring circuit configured to measure the period of the filtered signal and an output configured to output a value differing from the frequency of the single bit binary signal by the inverse of the measured period as the frequency to be determined.