Bandgap Voltage Reference With Alternating Amplifier Offset Trimming
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Solution Overview
Problem
Bandgap voltage references face precision issues due to package stress-induced changes and temperature variations, which can shift the bandgap voltage output, leading to reduced circuit precision, especially since traditional trimming methods are time-consuming and expensive, and introduce unwanted noise.
Innovation Solution
An automated trimming algorithm that alternately trims two offset-trimmable amplifiers, allowing one amplifier to be available for bandgap function while the other is being trimmed, using a switch matrix and trim controller to adjust input offsets in both functional and calibration configurations, ensuring continuous trimming across multiple temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional trimming methods are used to adjust amplifier offset, then manufacturing precision is improved, but loss of time increases and productivity decreases
Solution Approach 1:
The patent applies preliminary action by performing offset trimming during the factory testing phase before the product reaches the customer. The automated trimming algorithm trims amplifiers A and B during initial production testing, establishing their offset characteristics in advance. This eliminates the need for time-consuming customer-side adjustments while ensuring manufacturing precision is achieved during production.
Solution Approach 2:
The patent implements self-service through automated self-trimming algorithms that enable the amplifiers to trim themselves without external intervention. The system uses the amplifiers' own output signals and internal resources to perform offset trimming automatically during factory testing. This self-trimming capability significantly reduces manual intervention time and increases productivity while maintaining precision.
2Manufacturing precision
If extensive factory trimming is performed to maintain precision over temperature and stress variations, then manufacturing precision is improved, but productivity decreases
Solution Approach 1:
The patent applies segmentation by dividing the trimming process into two distinct phases: automated offset trimming during factory testing, and automated gain/offset trimming during customer operation. This segmentation allows simple offset trimming to be completed quickly during production (maintaining productivity), while more complex trimming occurs later during actual use (maintaining precision). The bandgap circuit is also segmented into multiple amplifiers that can be trimmed independently and alternately.
Solution Approach 2:
The patent implements periodic action through automated trimming algorithms that periodically adjust amplifier parameters during customer operation based on temperature and stress conditions. The system monitors operating conditions and performs trimming adjustments at appropriate intervals rather than continuously during production. This periodic approach maintains voltage stability without requiring extensive time-consuming trimming during the production phase.
3Manufacturing precision
If automated trimming algorithms are used to trim amplifiers during operation, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by designing the switch matrix and control logic to perform multiple functions: they manage alternating trimming of multiple amplifiers, handle both offset and gain trimming operations, and coordinate factory testing with customer-operated trimming. This multi-functional design consolidates what could be separate complex circuits into a single versatile control system, reducing overall device complexity while maintaining trimming accuracy.
Solution Approach 2:
The patent implements merging by combining the trimming control logic and switch matrix into an integrated automated system that manages multiple amplifiers simultaneously. Rather than having separate control circuits for each amplifier, the system merges control functions into a unified algorithm that alternates between trimming amplifiers A and B. This consolidation reduces the number of discrete components and simplifies the overall device architecture while achieving precise trimming.
Data Source
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AI summary
One example discloses a voltage reference, including: a bandgap circuit core having a first intermediate bandgap voltage output, a second intermediate bandgap voltage output, and a bandgap voltage reference output; an amplifier having a first input, a second input, an input offset, an output, and an input_offset_trim; a trim controller; a switch matrix coupled between the bandgap circuit, the amplifier and the trim controller; wherein the switch matrix has a functional configuration and a calibration configuration; wherein in the functional configuration of the switch matrix, the first intermediate bandgap voltage output is coupled to the first input of the amplifier and the second intermediate bandgap voltage output is coupled to the second input of the amplifier; and wherein in response to the calibration configuration of the switch matrix, the trim controller is coupled to adjust the input offset of the amplifier using the input_offset_trim.