PTAT Reference Generator Circuit Reducing Current and Area
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Solution Overview
Problem
Existing reference generator circuits for low power applications face challenges in minimizing current consumption and area occupancy, as they are often dominated by large resistors, leading to inefficiencies in power management.
Innovation Solution
The proposed solution involves a PTAT circuit with a first transistor and a resistive element, where an additional current source injects an up-scaled current into the resistive element, effectively reducing total current consumption by creating a pseudo resistance multiplier and reusing current, thereby minimizing area and power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a large resistor is used to reduce current consumption, then current consumption is reduced, but area occupancy increases
Solution Approach 1:
The patent combines the functions of current generation and current multiplication into a single integrated circuit. The PTAT current generator produces a base current that is then multiplied by a factor N through a current mirror configuration, achieving both low current consumption and compact area by merging multiple functions into one unified structure rather than using separate large resistor-based circuits
Solution Approach 2:
The patent changes the operating parameters by using a PTAT (Proportional To Absolute Temperature) current generator instead of a traditional large resistor. The current is scaled by a multiplication factor N determined by transistor size ratios and current mirror configurations, allowing the circuit to achieve equivalent current levels with much smaller physical dimensions
2Use of energy by moving object
If current consumption is reduced by half, then power efficiency improves, but resistor size needs to be increased by two times
Solution Approach 1:
The patent fundamentally changes the approach from using resistor value as the primary parameter for current control to using transistor current multiplication factor N. By generating a PTAT current and multiplying it through current mirrors with different transistor size ratios, the circuit achieves current scaling without proportionally increasing resistor area
Solution Approach 2:
The patent replaces the mechanical/resistive approach (using large physical resistors) with an electronic approach using active transistor circuits. The current multiplication is achieved through transistor biasing and current mirror effects rather than through resistive division, substituting a compact electronic mechanism for a large passive component
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 approach reduces current consumption by half and area occupancy by approximately half, while maintaining similar mismatch and area, or achieving similar current consumption in a smaller area, compared to conventional designs.
Implementation Method 1
a PTAT circuit including a first transistor coupled in series with a first resistive element at a first node, said first transistor configured to pass a first current to said first node
Data Source
AI summary
A PTAT circuit includes a first, second, third, and fourth transistors plus a resistor. The first and second transistors have control terminals coupled to each other. The third and fourth transistors have control terminals coupled to each other. The third transistor sources a first current to the first transistor and the fourth transistor sources a second current to the second transistor. The resistor is coupled at a node to the second transistor. A current source circuit sources additional current into the node that is derived from the first and second currents. In one implementation, the additional current is a scaled mirror of the second current. In another implementation, the additional current is a scaled mirror of the sum of the first and second currents. An output current is obtained by mirroring one of the first-third currents. A band-gap output voltage is obtained by applying the additional current across a resistance.