Sample-and-Hold Amplifier Offset Compensation for Temperature Drift
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Solution Overview
Problem
Semiconductor devices in portable SoC products face challenges in maintaining performance and accuracy due to temperature changes, which affect the characteristics and offset voltages in temperature sensing circuits, leading to signal distortion and reduced precision in analog-to-digital conversion.
Innovation Solution
A sample-and-hold amplification circuit with an offset compensation mechanism that forms different paths between input and output terminals in response to control signals, using capacitors and switches to store and reflect offset voltages, ensuring accurate amplification and conversion of temperature-related signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a temperature sensing circuit uses a CMOS device with threshold voltage-based output, then the circuit can generate temperature-dependent output voltage, but the offset voltage changes with temperature causing measurement precision degradation
Solution Approach 1:
The patent applies preliminary action by measuring and storing the offset voltage in advance during a calibration phase at a reference temperature. The offset compensation circuit saves this pre-measured offset value to a storage element before actual temperature measurements are taken. During operation, the pre-stored offset is subtracted from measured values to compensate for temperature-dependent drift, eliminating the need for real-time offset correction and maintaining measurement precision across varying temperatures.
Solution Approach 2:
The patent changes the parameter being measured from raw threshold voltage to offset-compensated threshold voltage. By introducing the offset compensation circuit that subtracts the pre-measured offset from the threshold voltage output, the system transforms the temperature-dependent parameter (raw voltage) into a temperature-independent parameter (compensated voltage), thereby improving measurement precision without requiring complex real-time correction mechanisms.
2Productivity
If the semiconductor device operates at high speed with refined processes, then productivity and performance improve, but temperature changes have greater impact on device characteristics
Solution Approach 1:
The patent implements feedback by continuously monitoring the threshold voltage output from the CMOS device and comparing it against the pre-stored offset value. The offset compensation circuit uses this feedback mechanism to adjust the measured threshold voltage by subtracting the offset component, thereby compensating for temperature-induced characteristic changes. This feedback loop maintains reliable operation at high speeds by correcting for thermal drift in real-time during measurement operations.
3Productivity
If an ADC circuit directly converts the analog output voltage without offset compensation, then the conversion process is simple and fast, but signal distortion occurs due to offset voltage
Solution Approach 1:
The patent applies preliminary action by performing offset measurement and storage before the ADC conversion process. The offset compensation circuit pre-calculates and stores the offset value during a calibration phase, then uses this pre-computed value to correct the analog signal before ADC conversion. This approach maintains fast conversion speed while eliminating signal distortion, as the offset correction is prepared in advance rather than computed during the time-critical ADC conversion process.
Data Source
AI summary
A sample-and-hold amplification circuit can include a sampling circuit configured to sample first and second input signals in response to first and second control signals to generate first and second sampled signals, an amplification circuit configured to amplify a voltage difference between the first and second sampled signals to generate first and second output signals, and an offset compensation circuit configured to form a first path between input and output terminals of the amplification circuit in response to the first control signal to store an offset of the input terminal and form a second path between the input and output terminals in response to the second control signal to reflect the offset to the output terminal.