Threshold-Voltage Reference Generator for Low-Voltage CMOS Supplies
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Solution Overview
Problem
Modern computer systems face challenges in generating reference voltages that remain stable across varying supply voltage levels and temperatures, as existing band gap circuits require large input power supplies and bipolar devices, which are difficult to fabricate and costly to implement.
Innovation Solution
A reference generator circuit using field-effect transistors with different threshold voltages, where the reference voltage is generated based on the difference between these threshold voltages, allowing for the use of low-voltage digital power supplies and minimizing temperature variation, and incorporating trim circuits for manufacturing variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If band gap circuits are used to generate reference voltages, then reference voltage stability is improved, but power consumption and device complexity increase
Solution Approach 1:
The patent changes the fundamental operating parameters by using field-effect transistors with different threshold voltages instead of bipolar transistors in band gap circuits. This parameter change enables reference voltage generation at lower supply voltages (0.8V to 1.2V) with reduced power consumption while maintaining stability through the threshold voltage difference method
Solution Approach 2:
The patent extracts and eliminates the need for complex bipolar devices and large input power supplies by using only field-effect transistors and digital power supplies. The solution takes out the problematic components (bipolar devices, large power supplies) while retaining the core function of reference voltage generation
2Measurement precision
If band gap circuits with bipolar devices are used, then reference voltage precision is improved, but manufacturing difficulty and cost increase
Solution Approach 1:
The patent replaces expensive, difficult-to-fabricate bipolar devices with inexpensive, easily manufactured field-effect transistors. Field-effect transistors are standard in CMOS technology and can be manufactured using conventional digital CMOS processes, making the reference voltage generator cost-effective and manufacturable
Solution Approach 2:
The patent substitutes bipolar device physics with field-effect transistor physics. By using the threshold voltage difference between two field-effect transistors instead of bipolar transistor voltage relationships, the solution achieves reference voltage precision through a different physical mechanism that is easier to manufacture
3Use of energy by moving object
If field-effect transistors with different threshold voltages are used, then power consumption is reduced, but temperature variation impact increases
Solution Approach 1:
The patent incorporates feedback mechanisms through trim circuits that allow adjustment of the reference voltage to compensate for temperature variations. The trim circuits provide a means to calibrate and maintain reference voltage accuracy across different temperature conditions, counteracting the temperature sensitivity introduced by using field-effect transistors
4Use of energy by moving object
If low-voltage digital power supplies are used, then power consumption is reduced, but reference voltage stability worsens
Solution Approach 1:
The patent changes the supply voltage parameter to low voltage levels (0.8V to 1.2V) and uses field-effect transistors whose threshold voltage difference is relatively insensitive to supply voltage variations. This parameter change enables stable reference voltage generation from unstable low-voltage digital power supplies
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 solution provides a stable reference voltage with reduced power consumption and manufacturing variability, eliminating the need for costly analog supply pins and bipolar devices, while maintaining precision and adaptability across temperature changes.
Implementation Method 1
A reference generator circuit includes a current source configured to generate a bias current using an input power supply. The plurality of devices are configured to generate, using the bias current, a reference voltage whose value is based on a first difference between the first threshold voltage and the second threshold voltage.
Data Source
AI summary
A reference generator circuit included in a computer system may employ multiple field-effect transistors to generate a reference voltage whose value is based on the threshold voltages of the multiple field-effect transistors. The reference generator circuit can include a current source that generates a bias current. One of more stages included in the reference generator circuit can generate, using the bias current, respective output voltages whose values are based on differences in threshold voltages of field-effect transistors included in the stages. The output voltages can be combined to generate different reference voltage values.