Temperature Signal Circuit Calibration for Amplification Error Compensation
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Solution Overview
Problem
Existing temperature measurement circuits in integrated circuits suffer from amplification errors due to mismatches between current sources and diodes, as well as amplifier offset, which are difficult to completely compensate for without introducing additional noise or requiring complex analog circuitry.
Innovation Solution
A circuit arrangement with switchable current sources and a control circuit that calculates and compensates for error terms by activating each current source individually and simultaneously, allowing for digital error correction and reducing mismatches through simple arithmetic operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional temperature measurement circuits using bipolar diodes and differential amplifiers are used, then temperature-proportional signals can be generated, but amplification errors occur due to mismatches between current sources and diodes and amplifier offset
Solution Approach 1:
The patent applies preliminary action by performing calibration measurements before actual temperature measurements. During calibration, the system measures and stores offset values and gain factors using known reference temperatures. These pre-determined correction parameters are then used to compensate for mismatches and amplifier offset during subsequent measurements, eliminating the need for complex real-time compensation circuitry.
Solution Approach 2:
The system implements feedback by using the calibration data (offset and gain factors) to correct subsequent temperature measurements. The stored calibration parameters are applied as feedback corrections to compensate for component mismatches and amplifier offset, thereby improving measurement reliability without requiring highly precise current sources or diodes.
2Measurement precision
If chopper technique or ΣΔ converter is used to compensate for mismatches, then measurement accuracy can be improved, but circuit complexity and additional noise or charge injection are introduced
Solution Approach 1:
The patent extracts the compensation function from the main measurement circuit by performing all mismatch compensation through digital processing of calibration data. Instead of using complex analog chopper circuits or ΣΔ converters, the system separates the calibration phase (where offset and gain are measured) from the measurement phase (where corrections are applied digitally), thereby simplifying the overall circuit architecture.
Solution Approach 2:
The system replaces complex analog compensation mechanisms (chopper circuits, ΣΔ converters) with digital signal processing. By measuring calibration parameters analogously and then applying corrections through digital arithmetic operations on stored offset and gain factors, the patent substitutes mechanical/analog complexity with simpler digital processing.
3Measurement precision
If highly precise current measurement is required to reduce mismatches, then measurement accuracy improves, but circuit requirements become more stringent and complex
Solution Approach 1:
The patent performs preliminary calibration measurements to determine and store offset and gain factors that characterize the actual behavior of current sources and diodes. By pre-characterizing the components during calibration, the system compensates for their imprecise behavior during normal operation without requiring the current sources or measurement circuits to be highly precise.
Solution Approach 2:
The system changes the approach from requiring precise component parameters (highly matched current sources and diodes) to using measured calibration parameters (offset and gain factors) for compensation. By transforming the problem from one of component precision to one of calibration data acquisition and digital processing, the patent relaxes circuit requirements while maintaining measurement accuracy.
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
This approach significantly reduces amplification errors in temperature measurements by eliminating mismatches and amplifier offset, while simplifying the circuit requirements and improving measurement precision without the need for highly precise current measurement.
Implementation Method 1
a first current source (1) arranged in common with a first switch (4) in a first current path. A second current source (2) with a second switch (5) is arranged in a second current path. An M-th current source (3) is arranged together with another switch (6) in a third current path. The three current paths each including a current source (1, 2, 3) and a switch (4, 5, 6) are connected to each other in a parallel circuit and connected between a power-supply voltage terminal (7) and the anode terminal of a diode (8). The cathode terminal of the diode (8) is connected to a reference potential terminal (9).
Implementation Method 2
The anode terminal of the diode (8) is further connected to a non-inverting input of a comparator (10), having an inverting input that can be fed a reference signal Vr. This signal can have an offset voltage Voff. The comparator (10) has an amplification factor g. The output of the comparator (10) is connected via an analog/digital converter (11) to a control circuit (12)
Data Source
AI summary
An arrangement and a method for providing a temperature-dependent signal. Several current sources (1, 2) are provided, which are switchably connected to one or more diodes (8). The conducting-state voltage of the diode is compared with a reference signal (Vr) in a comparator (10). A control circuit (12) controls the current sources (1, 2) so that for calibrating in each calibration step, only one of the current sources is activated and, in another calibration step, all of the current sources (1, 2) are activated. Therefore, error terms can be calculated, which allow a very exact provision of a temperature-dependent signal with respect to the matching of the current sources to each other.