Mixer-Based ADC Architecture for High Sampling Rates
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Solution Overview
Problem
Conventional analog to digital conversion systems face limitations in achieving high sampling rates due to practical constraints such as sampling difficulties, power consumption, and accuracy, particularly in interleaved architectures where subconverters must sample at the bandwidth of the overall system, leading to reduced speed advantages and increased power consumption.
Innovation Solution
A novel analog to digital conversion system that combines multiple subconverters using a signal distribution front end with limiting mixers and smoothing filters, followed by digital matrix filtering to achieve a higher sampling rate than individual subconverters, employing Walsh codes or orthogonal codes to combine digital outputs and correct aliasing errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If interleaved architectures are used to increase sampling rate, then sampling rate is improved, but power consumption increases and manufacturing precision requirements worsen
Solution Approach 1:
The system divides the high-speed sampling task into multiple subconverters operating at lower speeds. Each subconverter processes a portion of the signal spectrum, allowing them to operate below the full Nyquist frequency. The segmented architecture enables parallel processing that achieves high effective sampling rate while each individual converter consumes less power.
Solution Approach 2:
The invention changes the operating parameters of subconverters by allowing them to sample at rates below the overall system Nyquist frequency. By using a mixer-based front end with smoothing filters and digital matrix filtering, the system transforms the signal processing approach, enabling subconverters to operate at relaxed speeds while maintaining high effective sampling rate through spectral manipulation and digital reconstruction.
2Speed
If subconverters operate at full bandwidth to achieve high sampling rate, then sampling rate is improved, but device complexity and manufacturing precision requirements worsen
Solution Approach 1:
The signal bandwidth is segmented and distributed across multiple subconverters, each handling a portion of the total spectrum. The mixer-based front end with smoothing filters divides the frequency spectrum into manageable bands, allowing subconverters to operate at reduced bandwidth while the digital matrix filter reconstructs the full-bandwidth signal.
Solution Approach 2:
The invention introduces intermediary components including mixers with smoothing filters and a digital matrix filter that mediate between the low-bandwidth subconverters and the high-bandwidth output signal. These intermediaries transform and reconstruct the signal, enabling subconverters to operate at relaxed bandwidth while achieving high effective sampling rate.
3Ease of manufacture
If conventional sample-and-hold circuits are used, then simplicity is maintained, but sampling difficulties arise in certain technologies
Solution Approach 1:
The invention replaces conventional sample-and-hold circuitry with a mixer-based front end followed by digital sampling and reconstruction. This substitution eliminates the need for high-speed analog sample-and-hold circuits that are difficult to implement in certain technologies, replacing them with mixers, smoothing filters, and digital processing that are more readily implementable while achieving equivalent or superior sampling performance.
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 system effectively increases the sampling rate while reducing bandwidth requirements and sensitivity to sampling jitter, improving speed, accuracy, and power efficiency by operating subconverters below the Nyquist frequency and utilizing digital signal processing to correct errors.
Implementation Method 1
a limiting mixer in at least one of the signal paths to mix the analog signal with a mixing signal having at least two discrete levels
Implementation Method 2
a smoothing filter in the at least one signal path to filter the mixed analog signal
Data Source
AI summary
An analog to digital conversion system is disclosed which converts an analog signal to a digital representation thereof at a first sampling rate by distributing the analog signal to at least two signal paths, at least one signal path including a limiting mixer to mix the signal with a respective selected square wave and a smoothing (low pass) filter to filter the mixed signal before providing the mixed and filtered signal to a subconverter, the subconverter having a sampling rate less than the first sampling rate, and a digital matrix filter to combine the digital output of each subconverter to form a digital representation of the analog signal as sampled at the first rate.