Complementary Current Mirror V-I Converter for Low-Voltage Accuracy
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Solution Overview
Problem
Modern LIDAR systems require accurate and compact voltage-to-current converters that can operate at low voltages while consuming minimal power, as they need to handle multiple channels for input offset cancellation and output offset current adjustment to optimize signal range utilization, but existing solutions face challenges in maintaining accuracy due to base-emitter voltage offsets and increased component count.
Innovation Solution
The implementation of voltage-to-current converters using complementary current mirrors, where each current mirror consists of a pair of N-type and P-type transistors, ensures equal base-emitter voltages across all transistors, eliminating the base-emitter voltage offset error without the need for additional transistors or complex doping profiles, thus achieving accurate conversion with minimal power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional voltage-to-current converters are used, then conversion function is provided, but base-emitter voltage offsets cause accuracy degradation
Solution Approach 1:
The patent combines N-type and P-type transistors into complementary current mirrors, where the N-type transistor in one mirror pairs with the P-type transistor in the other mirror. This merging of complementary transistor types eliminates base-emitter voltage offsets without requiring additional correction circuits, thereby improving conversion accuracy while maintaining circuit simplicity.
Solution Approach 2:
The patent changes the transistor type parameter by using complementary N-type and P-type transistors instead of traditional single-type transistors. This parameter change ensures that base-emitter voltages are equal across all transistors in the complementary current mirrors, eliminating offset errors and improving measurement precision without increasing device complexity.
2Adaptability or versatility
If multiple channels are added for offset cancellation, then signal range utilization is optimized, but power consumption increases
Solution Approach 1:
The complementary current mirror circuit serves multiple functions simultaneously: it performs voltage-to-current conversion, cancels base-emitter voltage offsets, and enables multi-channel operation. By integrating these functions into a single circuit architecture, the patent achieves adaptability for multiple channels without proportionally increasing power consumption, as the same complementary structure handles all channels efficiently.
3Measurement precision
If additional transistors are used to correct voltage offsets, then accuracy is improved, but component count increases
Solution Approach 1:
The patent converts the inherent base-emitter voltage difference between N-type and P-type transistors, which is normally a harmful offset error, into a beneficial feature. By designing complementary current mirrors where N-type and P-type transistors are paired, the voltage offsets naturally cancel each other out. This approach improves accuracy without requiring additional correction transistors, as the harmful offset is transformed into a self-correcting mechanism within the existing transistor count.
Data Source
AI summary
Voltage-to-current converters that include two current mirrors are disclosed. In an example voltage-to-current converter each current mirror is a complementary current mirror in that one of its input and output transistors is a P-type transistor and the other one is an N-type transistor. Such voltage-to-current converters may be implemented using bipolar technology, CMOS technology, or a combination of bipolar and CMOS technologies, and may be made sufficiently compact and accurate while operating at sufficiently low voltages and consuming limited power.