Switchable Current Mirror Biasing Across Multiple Supply Voltages
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Solution Overview
Problem
Existing technologies face challenges in achieving accurate and efficient voltage supply independent current biasing for amplifiers, particularly in GaAs and GaN technologies where complementary p-channel field-effect transistors are not available, leading to issues with process, temperature, and supply voltage variations.
Innovation Solution
An enhanced current mirror system comprising a current controller, reference resistor, voltage adjuster, and comparator components that adjust and control the resistance of reference resistors based on supply voltage levels to maintain a consistent bias current, mitigating variations and ensuring accurate current biasing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed reference resistor is used in the current mirror, then the circuit is simple, but the bias current varies with supply voltage changes
Solution Approach 1:
The reference resistor is changed from a fixed value to a dynamically adjustable value through a switchable network. The controller adjusts the equivalent resistance based on supply voltage detection, allowing the circuit to adapt to different operating conditions and maintain stable bias current despite supply voltage variations.
Solution Approach 2:
The resistance value of the reference resistor is changed as a response to supply voltage changes. By detecting the supply voltage level and adjusting the equivalent resistance accordingly, the system compensates for supply voltage variations to maintain constant bias current.
2Reliability
If the reference resistor resistance is adjusted to compensate for supply voltage variations, then bias current stability improves, but the device complexity increases
Solution Approach 1:
The reference resistor is segmented into multiple discrete resistance elements that can be independently switched. This segmentation allows the controller to select appropriate resistance values based on supply voltage levels, achieving compensation without requiring a continuously variable resistor.
Solution Approach 2:
A controller component is introduced as an intermediary between the supply voltage source and the reference resistor network. The controller detects supply voltage levels and automatically adjusts the equivalent resistance, eliminating the need for manual adjustment and simplifying the overall system interface.
3Measurement precision
If multiple reference resistors are used for different supply voltages, then accuracy across voltage ranges improves, but the manufacturing complexity increases
Solution Approach 1:
The reference resistor network is designed to serve multiple functions: it provides appropriate reference resistance values for different supply voltage ranges and also enables the current mirror to operate accurately across various operating conditions. This multi-functionality eliminates the need for separate resistor networks for different voltage ranges.
Solution Approach 2:
Multiple reference resistors are merged into a single switchable network controlled by a unified controller. This combination allows the system to select the appropriate resistance value based on supply voltage level, achieving high accuracy across different voltage ranges while simplifying the manufacturing process compared to having separate resistor networks.
Data Source
AI summary
An enhanced current mirror can be utilized to accurately control a bias current associated with an amplifier. A current controller component (CCC) can employ the enhanced current mirror and can be associated with the amplifier. The CCC can comprise a comparator that can compare an adjusted supply voltage level to a reference voltage level, the adjusted supply voltage level relating to a supply voltage level of a supply voltage supplied to the amplifier and CCC. The CCC can control switching of an operational state of a transistor of the comparator to switch in or out a resistance of a reference resistor component associated with the supply voltage, based on a result of the comparison of the adjusted supply voltage level to the reference voltage level, to facilitate accurately controlling an amount of bias current associated with the amplifier. The CCC and amplifier can be situated on the same die.