Reference Voltage Generator Circuit Area Reduction
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Solution Overview
Problem
Conventional reference voltage generators face challenges in reducing circuit area, improving power supply rejection ratio (PSRR), and accommodating GaAs HBT process limitations due to the need for operational amplifiers and specific transistor types.
Innovation Solution
A reference voltage generator design utilizing a network of transistors and resistors, along with a diode unit, that adjusts transistor areas and resistance ratios to generate a stable reference voltage without an operational amplifier, enhancing PSRR and allowing for GaAs HBT process use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an operational amplifier is used to amplify control voltage to generate reference voltage, then the reference voltage can be generated, but the circuit area increases due to compensation capacitor
Solution Approach 1:
The patent removes the operational amplifier from the reference voltage generation circuit, extracting the problematic compensation capacitor that occupies circuit area. The reference voltage is generated directly through a network of transistors and resistors without requiring external amplification, thereby eliminating the need for large compensation capacitors while maintaining reference voltage generation functionality.
Solution Approach 2:
The patent uses multiple transistors with different area ratios (e.g., M1 and M2 with area ratio of 1:2, M3 and M4 with area ratio of 1:2) to create current mirrors that replicate and scale currents. This copying approach allows the circuit to generate the necessary voltage levels through current multiplication rather than using an operational amplifier, reducing circuit area while maintaining functionality.
2Reliability
If conventional reference voltage generator structure is used, then reference voltage can be generated, but power supply rejection ratio (PSRR) is poor and reference voltage is easily affected by power supply noise
Solution Approach 1:
The patent implements feedback mechanisms through the transistor network where the reference voltage is generated through interconnected transistors M1-M4 and resistors R1-R4. The circuit inherently provides feedback through the current mirrors and voltage division networks, which stabilize the reference voltage against power supply variations and reduce sensitivity to power supply noise, improving PSRR without requiring an operational amplifier.
3Ease of manufacture
If P-type MOSFET current source and N-type MOSFET circuit are required, then conventional reference voltage generator can operate, but GaAs HBT process cannot be used due to process limitations
Solution Approach 1:
The patent designs a universal reference voltage generation circuit that can be implemented using HBT transistors in GaAs process. The circuit topology using transistors M1-M4 with controlled area ratios and resistor networks R1-R4 provides multi-functional operation that adapts to different transistor types, including HBT, making the design compatible with GaAs manufacturing processes while maintaining reference voltage generation functionality.
Data Source
AI summary
A reference voltage generator includes a voltage generation circuit, an amplifier, a diode unit and a transistor. The voltage generation circuit includes an output terminal for outputting a reference voltage, a first terminal having an operational voltage, and a second terminal. The amplifier includes an input terminal coupled to the first terminal of the voltage generation circuit, an output terminal, a first terminal coupled to a first voltage terminal, and a second terminal. The diode unit includes a first terminal coupled to the second terminal of the amplifier, and a second terminal coupled to the second terminal of the voltage generation circuit and a second voltage terminal. The transistor includes a first terminal coupled to the first terminal of the amplifier, a second terminal coupled to the output terminal of the voltage generation circuit, and a control terminal coupled to the output terminal of the amplifier.