Multipath Chopper Amplifier Circuit for Gain-Preserving Noise Folding Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Multipath chopper amplifiers face performance limitations due to mismatch between different paths, leading to increased noise folding and reduced effective amplifier gain, particularly when chopping at high frequencies to avoid quantization noise folding.
Innovation Solution
A chopper circuit with multiple chopper devices in parallel circuit paths, each controlled by distinct clock signals with varying frequencies, where one path is chopped at a higher frequency than the others to minimize mismatches and reduce noise folding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If chopping is performed at high frequency (fs/2) to avoid quantization noise folding, then noise folding is reduced, but effective amplifier gain decreases and thermal noise increases
Solution Approach 1:
The amplifier is divided into multiple parallel paths (first path, second path, third path) with different chopping frequencies. The first path operates at fs/2 while the second and third paths operate at lower frequencies, allowing each path to handle different frequency components and reduce the overall impact of noise folding while maintaining effective gain through path combination
Solution Approach 2:
Each path is assigned a specific chopping frequency tailored to its function. The first path uses fs/2 chopping for noise folding suppression, while the second and third paths use lower frequencies optimized for their specific signal processing requirements, allowing local optimization of both noise performance and gain characteristics
2Object-affected harmful factors
If chopping frequency is increased to modulate flicker noise outside signal bandwidth, then flicker noise is reduced, but amplifier thermal noise increases when referred to input
Solution Approach 1:
The signal processing is segmented into multiple paths with different chopping frequencies. The first path at fs/2 effectively modulates flicker noise outside the signal bandwidth, while the second and third paths at lower frequencies contribute to maintaining overall signal quality with reduced thermal noise impact
Solution Approach 2:
The outputs of the three parallel paths are combined to produce the final amplified signal. This merging allows the benefits of high-frequency chopping (flicker noise modulation) from the first path to be combined with the lower thermal noise contribution from the second and third paths operating at lower frequencies, achieving overall noise optimization
Data Source
Figure 1~4
Figure 5~7
Figure 8~10
AI summary
A chopper circuit (100) for a multipath chopper amplifier (201) is described. The chopper circuit (100) comprises a first chopper device (110) in a first circuit path (111), wherein the first chopper device (110) is configured to be controlled by a first clock signal (315), which has a first frequency; and a second chopper device (120) in a second circuit path (121), parallel to the first circuit path (111), wherein the second chopper device (120) is configured to be controlled by a second clock signal (325), which has a second frequency, wherein the first frequency is greater than the second frequency. Furthermore, a corresponding method of chopping an input signal (102) is described.