Multi-Stage Voltage Reference Circuit for Low Noise Precision
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Solution Overview
Problem
Existing voltage reference circuits face challenges in achieving high precision and low noise while maintaining low quiescent current, making them unsuitable for applications requiring precise output voltage with low noise, especially in portable or battery-powered devices.
Innovation Solution
The proposed circuit includes a current mirror circuit, multiple stages of transistors, and a voltage divider network, which together generate a high precision output voltage with low noise without increasing the quiescent current. This is achieved by scaling the voltage threshold gap without scaling the resistors, thereby reducing thermal noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional voltage reference circuits are used to achieve high precision output voltage, then measurement precision is improved, but noise increases and quiescent current consumption increases
Solution Approach 1:
The voltage reference circuit is divided into multiple independent stages: a first stage generating a first reference voltage, a second stage generating a second reference voltage, and a voltage divider network. Each stage operates independently with its own transistor pair, allowing noise to be distributed and reduced across stages rather than concentrated in a single high-precision generator.
Solution Approach 2:
The patent transitions from conventional single-stage voltage reference generation to a multi-stage architecture operating in different voltage dimensions. The first stage operates at a higher voltage level while the second stage operates at a lower voltage level, with the voltage divider network scaling between these dimensions to produce the final reference voltage. This dimensional separation allows each stage to be optimized for its specific operating conditions, reducing overall noise.
2Measurement precision
If conventional voltage reference circuits are used to achieve high precision output voltage, then measurement precision is improved, but quiescent current consumption increases
Solution Approach 1:
The circuit is segmented into multiple stages, each consuming a portion of the total quiescent current. By distributing the current consumption across the first stage, second stage, and voltage divider network, each component can be optimized to operate at lower current levels while maintaining overall precision through the cascaded architecture.
Solution Approach 2:
The patent changes the operating parameters of each stage differently - the first stage operates with higher voltage and lower current, while the second stage operates with lower voltage and higher current. The voltage divider network transforms these parameter differences to produce the final reference voltage. This parameter differentiation allows the circuit to achieve high precision without requiring high quiescent current throughout the entire circuit.
3Power
If voltage threshold gap is scaled up to increase output voltage, then output voltage increases, but thermal noise increases due to resistor scaling
Solution Approach 1:
The voltage generation is segmented into two stages with different voltage levels. The first stage generates a higher voltage reference with lower noise, and the second stage generates a lower voltage reference that is then scaled by the voltage divider network. This segmentation allows the output voltage to be increased through the cascaded stages rather than through single-stage resistor scaling, thereby avoiding the thermal noise penalty.
Solution Approach 2:
The voltage divider network acts as an intermediary between the two transistor stages, transforming the voltage threshold gap into the final output voltage without requiring direct proportionality between resistor values and output voltage. This intermediary transformation allows the circuit to achieve high output voltage while keeping resistor values (and thus thermal noise) relatively low.
Data Source
AI summary
In described examples, a circuit includes a current mirror circuit. A first stage is coupled to the current mirror circuit. A second stage is coupled to the current mirror circuit and to the first stage. A voltage divider network is coupled to the second stage. The circuit includes an output transistor having first and second terminals, in which the first terminal of the output transistor is coupled to the first stage, and the second terminal of the output transistor is coupled to the voltage divider network.