Low-Voltage Bandgap Reference Circuit Using Segmented Bias Voltages
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Solution Overview
Problem
Existing band gap reference circuits in semiconductor devices are unable to generate a stable reference voltage under low supply voltages, leading to variations in output values due to temperature changes and limiting the operating voltage range of bipolar transistors.
Innovation Solution
A band gap reference circuit utilizing a voltage reference main circuit and a transimpedance amplifier to generate a stable reference voltage using multiple bias voltages, without a diode-connected structure, to overcome limitations in bipolar transistor operating voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a diode-connected metal oxide silicon transistor is used to bias the bipolar transistor, then the circuit structure is simplified, but the operating voltage range is limited by the voltage difference VDD-VD
Solution Approach 1:
The bias voltage generation is segmented into multiple independent voltage sources (first bias voltage, second bias voltage, third bias voltage) instead of using a single diode-connected transistor. This segmentation allows each voltage source to be optimized independently, enabling the bipolar transistor to operate across a wider voltage range while maintaining circuit functionality.
Solution Approach 2:
The patent introduces an intermediate voltage generation stage that converts the supply voltage into multiple bias voltages through a series of voltage conversion circuits. This intermediary approach allows the bipolar transistor to receive appropriately leveled bias voltages that accommodate low supply voltage conditions while maintaining the required voltage headroom for proper operation.
2Use of energy by moving object
If the supply voltage is reduced to minimize power consumption, then energy efficiency is improved, but the band gap reference circuit cannot generate a stable reference voltage
Solution Approach 1:
The patent changes the voltage parameters by generating multiple bias voltages with different voltage levels from the same supply voltage. This allows the band gap reference circuit to maintain proper voltage headroom and transistor operating conditions even when the supply voltage is reduced, thereby generating a stable reference voltage at lower power consumption levels.
Solution Approach 2:
The bias voltage generation circuit dynamically adjusts the voltage levels of multiple bias sources based on the supply voltage conditions. This dynamic adaptation enables the circuit to maintain stable reference voltage generation across varying supply voltage levels, including low voltage conditions where traditional circuits would fail.
3Adaptability or versatility
If multiple bias voltages are generated separately to overcome bipolar transistor voltage limitations, then the operating voltage range is extended, but the circuit complexity increases
Solution Approach 1:
The voltage conversion circuits generate multiple bias voltages (first, second, and third bias voltages) from a single supply voltage input. These multiple voltage outputs serve different functional purposes within the band gap reference circuit, allowing one multi-functional block to replace what would otherwise require multiple separate voltage generation circuits, thereby reducing overall complexity.
Solution Approach 2:
The patent merges the functions of multiple voltage generation circuits into a single integrated voltage conversion stage that produces all necessary bias voltages simultaneously. This consolidation approach extends the operating voltage range through multiple bias sources while avoiding the complexity of having separate, independent voltage generation circuits for each bias voltage.
Data Source
AI summary
Proposed is a band gap reference circuit under a low supply voltage capable of generating a band gap reference voltage even under a low supply voltage by using a plurality of bias voltages separately generated and a current source using these bias voltages without using a diode connected structure used in the related art while not being affected by limitations in the operating voltage of a bipolar transistor. The band gap reference circuit under a low supply voltage includes a voltage reference main circuit configured to generate a first node voltage and a second node voltage in response to a first bias voltage and a band gap reference voltage, and a transimpedance amplifier configured to generate the band gap reference voltage by amplifying a difference between the first node voltage and the second node voltage using the first bias voltage, a second bias voltage, and a third bias voltage.