Sidecar Auto-Zero Amplifier for Analog Offset Cancellation
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Solution Overview
Problem
Existing methods for correcting offset in analog amplifiers, such as main signal path chopping and chopper stabilization, suffer from issues like ripple at chopping frequency, high power consumption, and increased noise due to sampling processes.
Innovation Solution
The system employs a sidecar amplifier with multiple auto-zeroed gain stages, each with a gain at least 10 decibels smaller than the overall gain, to generate a compensation signal that corrects the offset in the analog amplifier, thereby reducing noise and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If main signal path chopping is used to compensate for offset, then offset compensation is achieved, but ripple at chopping frequency and reduced loop gain occur
Solution Approach 1:
The offset compensation function is segmented from the main signal path and implemented in a separate sidecar amplifier. The sidecar amplifier measures the offset voltage and generates compensation signals that are applied to the main amplifier, avoiding the need to chop the main signal path while still achieving offset compensation.
Solution Approach 2:
A sidecar amplifier is introduced as an intermediary component that measures the offset voltage and generates compensation signals. This mediator allows offset compensation without directly modifying the main signal path, thereby avoiding ripple and loop gain degradation.
2Measurement precision
If chopper stabilization is used to maintain settling behavior, then offset compensation is improved, but power consumption increases
Solution Approach 1:
The sidecar amplifier performs periodic auto-zeroing at low frequency to measure and store offset voltages, rather than continuous high-frequency chopping. This periodic action maintains settling behavior while significantly reducing power consumption compared to continuous chopper stabilization.
Solution Approach 2:
The sidecar amplifier performs preliminary offset measurement and storage before the main amplifier needs compensation. By pre-measuring and storing offset voltages in capacitors, the system maintains accurate settling behavior without requiring continuous power-consuming chopping operations.
3Measurement precision
If sidecar amplifier with sampling process is used to measure offset, then offset correction is achieved, but noise increases
Solution Approach 1:
The sidecar amplifier performs preliminary offset measurement during dedicated auto-zero phases and stores the measured offset voltages in capacitors. This preliminary action allows offset correction without requiring continuous sampling of the main signal path, thereby reducing noise.
Solution Approach 2:
The offset measurement and correction functions are segmented into separate phases: auto-zeroing phases for measurement and signal amplification phases for normal operation. This segmentation allows offset correction without continuous sampling noise in the main signal path.
4Object-generated harmful factors
If high switching speed is used for auto-zeroing of sidecar amplifier, then low-frequency noise reduction is improved, but power consumption increases
Solution Approach 1:
The sidecar amplifier uses periodic auto-zeroing at optimized low frequency to reduce low-frequency noise while minimizing power consumption. The periodic switching allows noise reduction without requiring high-speed continuous switching.
Solution Approach 2:
The system changes the switching frequency parameter to an optimized low frequency that is sufficient for noise reduction but low enough to minimize power consumption. This parameter optimization balances noise reduction performance with energy efficiency.
Data Source
AI summary
A system may include an analog amplifier configured to receive an input signal and generate an output signal based on the input signal and a sidecar amplifier coupled to the analog amplifier and configured to generate a compensation signal applied to the analog amplifier in order to correct a signal offset associated with the analog amplifier, the sidecar amplifier comprising a plurality of amplifier stages, each amplifier stage having a respective gain at least 10 decibels smaller than an overall gain of the sidecar amplifier.