Bandgap Reference Biasing for Temperature-Compensated IC Outputs
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Solution Overview
Problem
Existing integrated circuits using bandgap voltage reference (BGR) circuits struggle to generate temperature-stabilized output signals due to significant temperature dependence in subsequent stage circuits, particularly in voltage-to-current conversion circuits.
Innovation Solution
An integrated circuit design that incorporates a BGR-based voltage generator circuit and a subsequent stage circuit, where the output voltage of the BGR circuit is configured with non-zero temperature dependence to partially cancel the temperature characteristics of the subsequent stage circuit, using adjustable resistor resistances and transistor sizes to achieve temperature compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a BGR circuit is used to generate a temperature independent reference voltage, then the reference voltage stability is improved, but the subsequent stage circuit still exhibits significant temperature dependence that degrades the overall output signal stability
Solution Approach 1:
The patent applies preliminary anti-action by intentionally introducing a compensating voltage with opposite temperature coefficient into the reference voltage generation circuit. The compensation circuit generates a voltage that varies with temperature in the opposite direction to the drift of the subsequent stage circuit, thereby preemptively counteracting the temperature-induced errors before they affect the output signal. This allows the overall system to achieve temperature compensation without requiring perfect temperature independence from the BGR circuit itself.
2Reliability
If the output voltage of the BGR circuit is made completely temperature independent, then the reference voltage stability is improved, but the ability to compensate for temperature effects in the subsequent stage circuit is reduced
Solution Approach 1:
The patent employs parameter changes by making the reference voltage deliberately non-ideal with respect to temperature stability. Instead of optimizing for complete temperature independence, the invention adjusts the temperature coefficient parameter of the reference voltage to a specific non-zero value that enables optimal compensation. The compensation circuit's parameters (resistor ratios, transistor sizes, bias currents) are adjusted to generate a compensating voltage with the precise temperature dependence needed to cancel the subsequent stage's temperature drift, achieving better overall temperature stability than would be possible with a perfectly stable reference alone.
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 design effectively generates output signals that are stable with temperature, achieving improved temperature compensation by partially canceling the temperature dependence of subsequent stage circuits.
Implementation Method 1
The first load component is configured to cause the first output voltage to have a non-zero temperature dependence that at least partially cancels a temperature dependence of the output signal of the subsequent stage circuit
Data Source
AI summary
An integrated circuit includes a current mirror configured to provide a first current to a first node, provide a second current to a second node virtually shorted to the first node, and provide a third current to a voltage output node. The integrated circuit further includes a first pn junction element between the first node and a ground line, a first resistor element between the second node and the ground line, a second pn junction element coupled in series to the first resistor element, a first load component configured to generate an output voltage at the voltage output node, and a subsequent stage circuit configured to generate an output signal based on the output voltage. The first load component is configured to cause the output voltage to have a non-zero temperature dependence that at least partially cancels a temperature dependence of the output signal of the subsequent stage circuit.