SAR ADC Capacitor Switching Without Non-Overlap Delay
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Solution Overview
Problem
Successive approximation analog to digital converters face inefficiencies due to the need for non-overlap generators to prevent high side and low side switches from conducting simultaneously, leading to increased switching delays and reduced throughput.
Innovation Solution
Individual control of transistors to place both high side and low side switches in a high impedance state before comparator decisions, eliminating the need for non-overlap generators and reducing propagation delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-overlap generators are used to prevent high side and low side switches from conducting simultaneously, then switching accuracy is improved, but switching delays increase and throughput decreases
Solution Approach 1:
The patent removes the non-overlap generator circuit from the system entirely. Instead of using complex generator circuits to prevent simultaneous conduction, the invention uses a simplified control method where the microcontroller directly manages switch timing, extracting the unnecessary complexity while maintaining functional integrity.
Solution Approach 2:
The patent changes the control parameter from hardware-based non-overlap generation to software-based timing control. By using a microcontroller to manage switch activation sequences, the system transitions from fixed hardware timing to flexible software-controlled timing, reducing delays and improving throughput.
2Reliability
If non-overlap generators are used to prevent simultaneous switch conduction, then circuit reliability is improved, but propagation delays increase
Solution Approach 1:
The patent extracts and removes the non-overlap generator circuit that was causing propagation delays. By eliminating this intermediate hardware component, the control signal path is shortened, reducing propagation delays while maintaining circuit reliability through direct microcontroller control.
Solution Approach 2:
The patent replaces the hardware-based non-overlap generator mechanism with a software-based control system. This substitution eliminates the propagation delays inherent in hardware generator circuits while maintaining the functional requirement of preventing simultaneous switch conduction through software timing management.
3Reliability
If traditional switch control is used to prevent short circuits between reference voltages, then circuit safety is improved, but device complexity increases
Solution Approach 1:
The patent removes complex non-overlap generator circuits and replaces them with simplified microcontroller-based switch control. The microcontroller directly manages the timing and sequencing of switch activation, eliminating unnecessary intermediate circuits while maintaining circuit safety through software-controlled prevention of simultaneous conduction.
Solution Approach 2:
The patent makes the microcontroller serve multiple functions: it controls the successive approximation conversion process, manages capacitor array switching, and prevents simultaneous switch conduction. This multi-functionality consolidates control logic into a single component, reducing overall device complexity while maintaining circuit safety.
Data Source
AI summary
A successive approximation analog to digital converter comprising a plurality of capacitors which during a successive approximation conversion are selectively connectable to a first reference or a second reference under the command of a controller. During a conversion step where the connections of a given capacitor may be varied, the switches to the given capacitor are both placed in a high impedance state during a decision period of a comparator.