Continuous-Time Chopper Instrumentation Amplifier With Minimal Aliasing
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Solution Overview
Problem
Instrumentation amplifiers face challenges in achieving accurate low-frequency measurements with low noise and low power consumption, particularly in medical devices where discrete time architectures introduce aliasing and chopper-stabilized designs have limited bandwidth and ripple issues.
Innovation Solution
A chopper-stabilized instrumentation amplifier with a differential architecture and a mixer amplifier that uses chopping at low impedance nodes and feedback to eliminate noise and offset, operating as a continuous time system to minimize aliasing and achieve stable measurements at low frequencies with very low power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a discrete time switched capacitor architecture is used, then the instrumentation amplifier can be implemented, but aliasing of noise and signals occurs undermining measurement accuracy
Solution Approach 1:
The patent replaces the discrete time switched capacitor architecture with a continuous time chopper-stabilized architecture. This substitution eliminates the sampling process that causes aliasing in discrete time systems, thereby maintaining measurement accuracy while still enabling practical implementation of the instrumentation amplifier.
Solution Approach 2:
The patent changes the operational mode from discrete time sampling to continuous time operation with chopper stabilization. By modifying the time domain characteristics and using frequency modulation techniques, the system achieves both implementability and high measurement accuracy without aliasing errors.
2Measurement precision
If a chopper stabilized architecture is used, then noise and offset are removed from the output signal, but the bandwidth is limited producing large ripple in the passband
Solution Approach 1:
The patent employs dynamic chopping techniques where the chopper frequency and modulation scheme are optimized to maintain high bandwidth. By using differential chopping and dynamic element matching, the system achieves both noise rejection and wide bandwidth without large passband ripple, making the frequency response more flat and predictable.
3Use of energy by moving object
If chopper stabilization is implemented at low power, then power consumption is reduced, but dynamic limitations such as glitching occur
Solution Approach 1:
The patent incorporates feedback mechanisms in the chopper-stabilized architecture to suppress glitching and improve signal stability. By using negative feedback loops and carefully designed compensation networks, the system maintains reliable low-frequency measurements even at low power consumption levels, eliminating the dynamic limitations of traditional chopper designs.
Data Source
AI summary
This disclosure describes a chopper stabilized instrumentation amplifier. The amplifier is configured to achieve stable measurements at low frequency with very low power consumption. The instrumentation amplifier uses a differential architecture and a mixer amplifier to substantially eliminate noise and offset from an output signal produced by the amplifier. Dynamic limitations, i.e., glitching, that result from chopper stabilization at low power are substantially eliminated through a combination of chopping at low impedance nodes within the mixer amplifier and feedback. The signal path of the amplifier operates as a continuous time system, providing minimal aliasing of noise or external signals entering the signal pathway at the chop frequency or its harmonics. The amplifier can be used in a low power system, such as an implantable medical device, to provide a stable, low-noise output signal.