PVT-Independent Reference Current Circuit Design
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Solution Overview
Problem
Existing reference current circuitry in electronic devices is prone to variations due to process, voltage, and temperature (PVT) changes, leading to resource consumption issues such as space and power constraints, particularly in mobile devices.
Innovation Solution
A PVT-independent reference current is generated using a bandgap circuit that outputs a stable voltage and gate signal, allowing for the creation of complementary-to-absolute-temperature (ICTAT) and proportional-to-absolute-temperature (IPTAT) currents, which are then mirrored and summed to cancel out PVT variations, thereby producing a stable reference current without the need for resource-intensive circuit elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional reference current circuitry is used to generate reference current, then the circuit can provide current to components, but the generated current deviates from target magnitude due to PVT variations
Solution Approach 1:
The patent changes the operating parameters of transistors by utilizing the intrinsic relationship between gate-source voltage and drain current in saturation region. By carefully selecting transistor dimensions and biasing conditions, the circuit exploits parameter variations to achieve PVT-independent current generation without requiring additional compensation components
Solution Approach 2:
The reference current circuit uses itself to generate the required bias conditions. The output current of the circuit is fed back to establish the gate-source voltages of the transistors, creating a self-biasing mechanism that automatically compensates for PVT variations and maintains accurate current magnitude
2Reliability
If resource-intensive circuit elements are used to achieve PVT independence, then current stability improves, but device space and power consumption increase
Solution Approach 1:
The patent makes the transistor circuit perform multiple functions simultaneously: it generates the reference current, establishes its own bias conditions, and compensates for PVT variations all within the same circuit blocks. This eliminates the need for separate compensation circuits and reduces overall device area
Solution Approach 2:
The patent extracts the PVT compensation functionality from separate compensation circuits and integrates it into the core current generation transistors. By removing the need for external compensation components, the circuit achieves PVT independence with minimal area overhead
3Reliability
If resource-intensive circuit elements are used to achieve PVT independence, then current stability improves, but power consumption increases
Solution Approach 1:
The circuit generates its own bias conditions from its output current, eliminating the need for external power-intensive reference voltage sources or additional bias generation circuits. This self-biasing mechanism significantly reduces power consumption while maintaining PVT independence
Solution Approach 2:
The patent combines the reference current generation function with the bias generation function into a single integrated circuit block. By merging these functions, the circuit eliminates redundant power consumption associated with separate bias generation circuits while achieving PVT-independent operation
Data Source
AI summary
Systems and devices are provided for generating a process, voltage, temperature (PVT)-independent reference current in a resource-efficient manner. A semiconductor device may include a bandgap circuit that outputs a reference voltage and gate signal. The semiconductor device may also include a reference current circuit that includes a complementary-to-absolute-temperature (CTAT) current generation portion and a variation-independent reference current generation portion. The variation-independent reference current generation portion may receive the gate signal from the bandgap circuit, apply the gate signal to a proportion-to-absolute temperature (PTAT) branch of the variation-independent reference current generation portion, and generate mirror PTAT and CTAT currents. The reference current circuit may also include a reference node that generates the reference current supply based at least in part on the mirror CTAT current and the mirror PTAT current.