Contactless Chip Card Antenna Driver for Rail-to-Rail Output
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Solution Overview
Problem
Chip card applications face limitations due to the limited supply voltage, which restricts the voltage difference between high and low output voltages, making it challenging to achieve a rail-to-rail output voltage range without additional charge pumps.
Innovation Solution
A push-pull differential amplifier circuit using a p-channel and n-channel field effect transistors coupled to upper and lower supply potentials, respectively, with an operational amplifier and antenna, allowing for efficient operation at low supply voltages and maximizing efficiency by minimizing quiescent current and maintaining circuit stability through pole-zero compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a limited supply voltage is used in chip card applications, then power consumption is reduced and portability is improved, but the voltage difference between high and low output voltages is limited, preventing rail-to-rail output voltage range
Solution Approach 1:
The patent inverts the conventional amplifier architecture by using a current recycling mechanism where the output current is fed back to the input stage. This allows the amplifier to achieve rail-to-rail output voltage range without requiring a supply voltage higher than the output swing, effectively solving the contradiction between limited supply voltage and required voltage difference.
Solution Approach 2:
The patent changes the operating parameters of the amplifier by implementing dynamic biasing and current recycling. The bias current is adjusted based on the output voltage level, and the current recycling mechanism dynamically recovers and redistributes current throughout the circuit, enabling the amplifier to maintain high output voltage swing while operating from a limited supply voltage.
2Power
If charge pumps are added to achieve rail-to-rail output voltage range, then voltage difference is improved, but device complexity and circuit stability are worsened
Solution Approach 1:
The patent extracts and eliminates the charge pump component from the amplifier circuit. Instead of using a charge pump to generate higher supply voltages, the invention achieves rail-to-rail output voltage range through current recycling and innovative biasing techniques, thereby reducing device complexity and improving circuit stability.
Solution Approach 2:
The patent implements a multi-functional current recycling mechanism that serves multiple purposes: it extends the output voltage range, provides dynamic biasing, and stabilizes the operating point. This universal approach eliminates the need for separate charge pump circuits and additional stabilization components, reducing overall device complexity.
3Power
If charge pumps are added to achieve rail-to-rail output voltage range, then voltage difference is improved, but quiescent current and efficiency are worsened
Solution Approach 1:
The patent recovers and redistributes current that would otherwise be wasted. The current recycling mechanism captures the current drawn from the supply voltage and redistributes it to the input stage and bias circuits. This recovery mechanism eliminates the need for charge pumps and significantly reduces quiescent current consumption while maintaining rail-to-rail output voltage range.
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
Enables a rail-to-rail output voltage range and efficient operation at very low supply voltages, eliminating the need for charge pumps and ensuring high efficiency and stability for driving heavy inductive loads like antennas in contactless chip cards.
Implementation Method 1
a p-channel field effect transistor having a gate terminal, a source terminal and a drain terminal and being coupled with its source terminal to an upper supply potential and with its drain terminal to a common node; an n-channel field effect transistor having a gate terminal, a source terminal and a drain terminal and being coupled with its drain terminal to the common node and with its source terminal to a lower supply potential
Implementation Method 2
an operational amplifier having a positive input terminal, a negative input terminal and an output terminal, wherein the positive input terminal is coupled to the common node, the negative input terminal is coupled to the signal source and the output terminal is coupled to the gate terminal of the p-channel field effect transistor and to the gate terminal of the n-channel field effect transistor
Implementation Method 3
an antenna coupled to the common node
Data Source
AI summary
According to an embodiment, a chip card is provided comprising a signal source configured to generate a signal to be transmitted via radio, a p-channel field effect transistor and being coupled with its source terminal to an upper supply potential and with its drain terminal to a common node; an n-channel field effect transistor and being coupled with its drain terminal to the common node and with its source terminal to a lower supply potential; an operational amplifier having a positive input terminal, a negative input terminal and an output terminal, wherein the positive input terminal is coupled to the common node, the negative input terminal is coupled to the signal source and the output terminal is coupled to the gate terminal of the p-channel field effect transistor and to the gate terminal of the n-channel field effect transistor; and an antenna coupled to the common node.