Switched Capacitor Chip Supply for Power Noise Rejection
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Solution Overview
Problem
Conventional methods for rejecting power supply noise in circuit chips require large layout areas and result in excessively long settling times due to the use of resistors in low-pass filters.
Innovation Solution
A circuit chip design incorporating a switch unit, an energy storage unit, and an operating circuit, where the switch unit selectively turns on a connection path between the power supply voltage and the energy storage unit based on a clock signal, allowing the energy storage unit to generate a storage voltage and reducing power supply noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a low-pass filter including a resistor and capacitor is used to filter power supply noise, then power supply noise is rejected, but the resistor occupies a large layout area and causes excessively long settling time
Solution Approach 1:
The patent extracts and removes the resistor component from the traditional low-pass filter circuit. By using only capacitors (energy storage units) to implement noise filtering, the design eliminates the need for resistors, thereby significantly reducing layout area while maintaining power supply noise rejection capability
Solution Approach 2:
The patent changes the filtering mechanism from resistive-capacitive time constant-based filtering to capacitor-based energy storage and voltage stabilization. This parameter change allows the circuit to achieve noise rejection without the settling time issues caused by large resistors
2Object-affected harmful factors
If a low-pass filter including a resistor and capacitor is used to filter power supply noise, then power supply noise is rejected, but the settling time becomes excessively long
Solution Approach 1:
By removing the resistor from the filtering circuit and using only capacitors controlled by switch units, the patent eliminates the RC time constant that causes long settling times. The energy storage capacitors can charge and discharge rapidly, achieving noise rejection with much faster settling
Solution Approach 2:
The patent introduces dynamically controlled switch units that can rapidly connect and disconnect the energy storage capacitors from the power supply. This dynamic control allows the circuit to quickly respond to noise events and settle, overcoming the static limitations of traditional RC filters
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
This design effectively reduces power supply noise, improves the power supply rejection ratio (PSRR), and saves layout area by eliminating the need for resistors, while also reducing settling time.
Implementation Method 1
The energy storage unit is coupled to the second connection terminal of the switch unit. When the switch unit turns on the first connection path, the energy storage unit is configured to generate a storage voltage on the second connection terminal according to the power supply voltage.
Data Source
AI summary
A circuit chip with power supply noise rejection includes a switch unit, an energy storage unit, and an operating circuit. The switch unit has a first connection terminal and a second connection terminal. The first connection terminal is adapted to receive a power supply voltage. The switch unit is configured to selectively turn on a first connection path between the first connection terminal and the second connection terminal according to a clock signal. The energy storage unit is coupled to the second connection terminal. When the switch unit turns on the first connection path, the energy storage unit is configured to generate a storage voltage on the second connection terminal according to the power supply voltage. The operating circuit is coupled to the second connection terminal, and the operating circuit is configured to operate according to the storage voltage.