Bandgap Reference Voltage Circuit for PVT-Stable Bias Control
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Solution Overview
Problem
Semiconductor devices face challenges in maintaining a stable reference voltage due to variations in power supply voltage caused by Process, Voltage, and Temperature (PVT) fluctuations, leading to unfavorable operating characteristics and potential malfunctions.
Innovation Solution
A semiconductor device is designed with a reference voltage generation circuit that includes a band gap circuit to produce voltages with temperature-dependent properties, a comparator to compare these voltages, and a driver to maintain a stable reference voltage output, ensuring the voltage level remains constant despite PVT variations and sharp increases in power supply voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reference voltage generator is provided to supply constant voltage to other circuits, then the operating stability is improved, but the device complexity increases due to additional circuit components
Solution Approach 1:
The patent combines the reference voltage generation function with the existing power supply voltage input structure. The reference voltage generator is integrated into the power supply path, where it processes the input voltage VDD to produce a stable reference voltage VREF. This merging approach allows the system to benefit from a dedicated reference voltage source without adding completely separate circuitry, thus improving reliability while controlling complexity.
Solution Approach 2:
The reference voltage generator acts as an intermediary component between the power supply voltage VDD and the various internal circuits. It receives the potentially variable input voltage and transforms it into a stable reference voltage that can be used by other circuits. This intermediary function isolates the internal circuits from PVT variations in the power supply, improving their operating stability without requiring them to directly handle the variable input voltage.
2Ease of operation
If the power supply voltage is used directly as bias voltage, then the device operation is simplified, but the reference voltage stability deteriorates under PVT variations
Solution Approach 1:
The reference voltage generator serves as an intermediary between the power supply voltage VDD and the bias voltage requirements of internal circuits. Instead of using VDD directly as bias voltage (which would be simple but unstable), the generator transforms VDD into a stable reference voltage VREF that can then be used for biasing. This intermediary transformation maintains ease of operation while solving the stability problem under PVT variations.
Solution Approach 2:
The reference voltage generator changes the voltage parameter from the raw power supply voltage VDD to a stabilized reference voltage VREF. This parameter transformation involves processing the input voltage through circuitry that compensates for PVT variations, thereby maintaining a stable output voltage level regardless of changes in the input voltage, temperature, or process conditions.
3Reliability
If a band gap circuit is used to generate stable reference voltage, then the voltage stability under temperature variations is improved, but the device complexity increases
Solution Approach 1:
The band gap circuit is merged with the reference voltage generator structure, combining temperature compensation functionality with voltage generation. The band gap circuit's inherent temperature stability characteristics are integrated into the overall reference voltage generation process, allowing the system to achieve stable voltage output across temperature variations without adding completely separate temperature compensation circuitry.
4Measurement precision
If the reference voltage generator is designed to compensate for PVT variations, then the operating precision is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The reference voltage generator is designed to actively change and adjust voltage parameters to compensate for PVT variations. By monitoring or anticipating changes in process, voltage, and temperature conditions, the circuit dynamically adjusts its output to maintain a stable reference voltage level. This parameter adjustment capability improves operating precision while the integrated design keeps the complexity increase manageable.
Data Source
AI summary
A semiconductor device includes: a first reference voltage generator for generating a first reference voltage; a first band gap circuit for dividing a voltage at a second reference voltage output node to produce a first and a second band gap voltages having a property relative to temperature variations; a first comparator for receiving the first reference voltage as a bias input and comparing the first band gap voltage with the second band gap voltage; and a first driver for pull-up driving the second reference voltage output node in response to an output signal of the first comparator.