Galvanically Isolated ADC Encoding With Fewer ON Bits
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Solution Overview
Problem
Power-constrained systems face challenges in using higher resolution analog-to-digital converters (ADCs) due to increased current consumption and data transfer errors, which can impact the operational latency and dynamic range of these systems.
Innovation Solution
The implementation of a data channel with an isolated Nyquist-rate ADC circuit, such as a successive approximation register (SAR) ADC, that reduces energy consumption by minimizing the number of ON bits in the transmit data, and includes error correction mechanisms to mitigate data transfer errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If higher resolution ADCs are used, then measurement precision is improved, but use of energy worsens
Solution Approach 1:
The 16-bit ADC data is segmented into two separate transmission channels: a first data channel transmitting the most significant bits (MSBs) and a second data channel transmitting the least significant bits (LSBs). This segmentation allows the system to use higher resolution ADCs while managing power consumption by transmitting data in parts through different modulation schemes.
Solution Approach 2:
The system dynamically adjusts transmission parameters based on power availability. When power is constrained, it transmits only MSBs at full data rate. When power is available, it transmits both MSBs and LSBs, achieving higher effective resolution without continuously consuming maximum power.
2Measurement precision
If higher resolution ADCs are used, then measurement precision is improved, but device complexity worsens
Solution Approach 1:
The data transmission system is divided into two independent channels: one for MSBs using one modulation scheme and another for LSBs using a different modulation scheme. This segmentation simplifies the overall system by allowing each channel to be optimized independently rather than transmitting all bits through a single complex channel.
Solution Approach 2:
The patent introduces an intermediary processing stage that separates the ADC output into MSB and LSB components before transmission. This intermediary structure manages complexity by organizing the transmission process into distinct, manageable stages rather than handling all 16 bits simultaneously through a single complex transmission path.
3Productivity
If data transmission rate is increased, then productivity is improved, but use of energy worsens
Solution Approach 1:
The system dynamically adjusts the data transmission rate and resolution based on power availability. During high-power periods, it transmits at full rate with complete 16-bit resolution. During low-power periods, it maintains full data rate but transmits only MSBs, achieving acceptable productivity with reduced energy consumption.
Solution Approach 2:
The system transmits only a partial set of data bits (MSBs only) when power is constrained, rather than transmitting all 16 bits. This partial action maintains acceptable productivity for many applications while significantly reducing the energy required for data transmission.
Data Source
AI summary
A data channel includes a power constrained first channel portion to receive energy from a limited power source and a non-power constrained second channel portion to receive energy from a different power source than the first channel portion. The first channel portion includes an ADC circuit to output an ADC data sample, a first transmitter circuit configured to serially transmit data that includes ON bits and OFF bits, and logic circuitry configured to derive transmit data from the ADC data sample. The transmitter circuit uses more energy transmitting the ON bits than the OFF bits, and the derived transmit data has a reduced number of the ON bits from the ADC data sample. The second channel portion includes a first receiver circuit to receive the derived transmit data from the first transmitter circuit of the first channel portion.