Bootstrap Switch Circuit Using Series Transistor to Block GIDL
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Gate-induced drain leakage (GIDL) in field effect transistors (FETs) leads to increased leakage current, affecting circuit performance and signal-to-noise and distortion ratio (SINAD) in applications like multiplexer designs, particularly in 16-bit successive approximation register (SAR) analog-to-digital converters (ADCs).
Innovation Solution
A bootstrap switch circuit is designed with a leakage protection transistor, controlled by a second gate signal, which is connected in series with the transistor-based switch to reduce GIDL. This circuit includes a first gate driver to manage the switching modes and a second gate driver to control the leakage protection transistor, ensuring it remains below the GIDL threshold, eliminating leakage current without external references or monitoring circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high voltage is applied to the drain when the gate is grounded, then the transistor can function as a switch, but gate induced drain leakage (GIDL) occurs causing increased leakage current
Solution Approach 1:
A leakage protection transistor is introduced as an intermediary component connected in series with the transistor-based switch. This intermediary transistor is controlled by a second gate signal to prevent GIDL leakage current from flowing through the main switch transistor, thereby protecting the switching function while eliminating the harmful leakage effect.
Solution Approach 2:
The circuit dynamically changes the voltage parameters by applying different gate signals (first gate signal for switching control, second gate signal for leakage protection) at different times. During sampling mode, the leakage protection transistor is turned on to block GIDL, while during hold mode it is turned off, thus adapting the electrical parameters to different operational requirements.
2Object-generated harmful factors
If a leakage protection transistor is added to reduce GIDL, then leakage current is reduced, but the device complexity increases
Solution Approach 1:
The leakage protection transistor is integrated into the existing bootstrap switch circuit architecture, serving multiple functions: it protects against GIDL leakage while maintaining compatibility with the existing sampling and hold mode operations. The second gate driver is synchronized with the first gate driver to coordinate the switching actions, making the protection mechanism part of the overall circuit functionality rather than a separate add-on.
Data Source
Figure 1
Figure 2A~2E
Figure 3
AI summary
A bootstrap switch circuit includes a transistor-based switch controlled by a first gate signal and a leakage protection transistor controlled by a second gate signal configured to reduce gate induced drain leakage in the transistor-based switch A first gate driver is included that produces a first gate signal at its output so that the first gate signal turns on the transistor-based switch during a sampling mode and turns off the transistor-based switch during a hold mode. A second gate driver is included that produces a second gate signal at its output and to receive the output signal of the bootstrap switch circuit so that the second gate signal turns on the leakage protection transistor during the sampling mode and turns off the leakage protection transistor during the hold mode and the second gate signal is based upon the output signal of the bootstrap switch circuit.