Analog Compensation Circuit for PVT Variations
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Solution Overview
Problem
Existing analog compensation circuits for integrated circuits face challenges in efficiently addressing process, voltage, and temperature (PVT) variations, leading to increased energy consumption, silicon area usage, and production costs due to reliance on bandgap voltage references and high-precision resistors.
Innovation Solution
A compensation circuit that generates a constant reference current directly from an on-chip low voltage supply, using a PTAT and NTC current generation mechanism, and a sensing circuit based on a current conveyor to detect PVT variations, eliminating the need for bandgap references and high-precision resistors, thereby reducing power consumption and silicon area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If bandgap type voltage reference blocks and integrated resistors are used to generate reference current, then PVT compensation accuracy is improved, but energy consumption and silicon area increase
Solution Approach 1:
The patent extracts and eliminates the bandgap voltage reference block and integrated resistors from the compensation circuit, replacing them with a direct current generation approach using transistors and current mirrors that operate directly from the supply voltage, thereby removing the energy-consuming and area-intensive components while maintaining PVT compensation functionality
Solution Approach 2:
The patent uses current mirror circuits to replicate and distribute the reference current to multiple buffer circuits, replacing the need for individual precision resistors in each buffer, thus reducing both silicon area and energy consumption while maintaining accurate current distribution across all buffers
2Measurement precision
If bandgap type voltage reference blocks and integrated resistors are used to generate reference current, then PVT compensation accuracy is improved, but silicon area increases
Solution Approach 1:
The patent removes the bandgap voltage reference block and integrated resistors from the circuit design, replacing them with a compact current generation approach using transistors and current mirrors that consume minimal silicon area while maintaining PVT compensation accuracy
Solution Approach 2:
The patent merges the reference current generation function with the buffer circuit operation itself, using the supply voltage directly to generate reference current through transistor-based circuits, thereby eliminating separate reference voltage generation blocks and reducing overall silicon area
3Measurement precision
If high precision external resistors are used for current conversion, then PVT compensation accuracy is improved, but production costs increase
Solution Approach 1:
The patent replaces expensive high precision external resistors with standard-value resistors and transistor-based current generation circuits that are cheaper to manufacture, using the process variations of standard components to achieve the required precision through current mirroring and matching techniques
4Reliability
If voltage-to-current converters are used to generate reference current, then PVT compensation is achieved, but energy consumption increases
Solution Approach 1:
The patent replaces the voltage-to-current converter mechanism with a direct current generation approach using transistor-based current mirrors that operate directly from the supply voltage, eliminating the energy-consuming voltage conversion stage while maintaining accurate PVT compensation
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
The solution effectively compensates for PVT variations with reduced energy consumption and silicon area usage, while lowering production costs by directly generating a constant reference current and sensing PVT variations using a current conveyor, enhancing the noise immunity and timing accuracy of output buffer circuits.
Implementation Method 1
using a proportional-to-absolute-temperature (PTAT) and negative temperature coefficient (NTC) current generation mechanism
Implementation Method 2
using a proportional-to-absolute-temperature (PTAT) and negative temperature coefficient (NTC) current generation mechanism
Data Source
AI summary
The present disclosure relates to a compensation circuit for providing compensation over PVT variations within an integrated circuit. Using a low voltage reference current source, the compensation circuit generates directly, from an on-chip reference low voltage supply (VDD), a reference current (Iref) that is constant over PVT variations, whereas a detection current (Iz) that is variable over PVT variations is generated by a sensing circuit, which is based on a current conveyor, from a low voltage supply (VDDE−VDD) applied across a single diode-connected transistor (M10) corresponding to a voltage difference between two reference low voltage supplies. Both currents (Iref, Iz) are then compared inside a current mode analog-to-digital converter that outputs a plurality of digital bits. These digital bits can be subsequently used to compensate for PVT variations in an I/O buffer circuit.