Charge Pump Circuit Body Biasing for Leakage Reduction
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Solution Overview
Problem
Conventional Dickson charge pump circuits face inefficiency due to high on-resistance in transistors M3 and M4, leading to slow voltage response at the body of transistor M1, resulting in leakage current and reduced circuit efficiency.
Innovation Solution
The charge pump circuit design includes a fourth capacitor (C1B) connecting the body of the first transistor to its drain, with a capacitance significantly larger than parasitic capacitance, to enhance voltage response speed and prevent leakage current by ensuring the body voltage remains lower than the input voltage, thus eliminating parasitic BJT activation during the 'Off cycle'.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional Dickson charge pump circuit uses transistors M3 and M4 to bias the body of transfer MOS M1, then the circuit structure is simple, but the on-resistance is large causing slow voltage response at the body of M1
Solution Approach 1:
A dedicated body bias transistor (M_body) is introduced as an intermediary component to directly control the body voltage of the transfer MOS (M1). This intermediary transistor provides a low-impedance path for body biasing, enabling fast voltage response without complicating the overall circuit architecture significantly.
Solution Approach 2:
The body bias voltage is dynamically adjusted by controlling the gate voltage of the body bias transistor M_body through a separate clock signal (CKB). This parameter change approach allows the body voltage to follow the input voltage changes rapidly, improving the voltage response speed.
2Loss of energy
If the body of M1 does not follow the voltage toggling on source and drain of M1, then the circuit structure remains simple, but leakage current increases due to parasitic BJT activation
Solution Approach 1:
The body bias transistor M_body proactively counteracts the voltage mismatch between the body and the source/drain of M1 by dynamically adjusting the body voltage. This preliminary anti-action prevents the activation of parasitic BJTs before leakage current can occur, thereby reducing energy loss.
3Loss of energy
If transistor on-resistance is reduced to improve voltage response, then leakage current decreases, but device complexity and power consumption increase
Solution Approach 1:
The body bias transistor M_body serves multiple functions: it provides low-impedance body biasing to reduce leakage current, maintains proper transistor operation during voltage transitions, and works cooperatively with the existing clocking network. This multi-functionality achieves energy efficiency without proportionally increasing complexity.
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 increases power efficiency by 36% and enhances maximum output current by 22%, while maintaining low leakage current and reducing power loss through optimized capacitor sizing and dynamic power supply management.
Implementation Method 1
a fourth capacitor connecting body of the first transistor to drain of the first transistor
Data Source
AI summary
A charge pump circuit includes a plurality of stages. Each stage of the charge pump circuit includes: a first transistor, drain of the first transistor being output of the stage, source of the first transistor being input of the stage; a second transistor, gate of the second transistor being connected to source of the first transistor, drain of the second transistor being connected to drain of the first transistor, source of the second transistor being connected to gate of the first transistor, body of the second transistor being connected to body of the first transistor; and a third transistor, gate of the third transistor being connected to drain of the first transistor, drain of the third transistor being connected to source of the first transistor, source of the third transistor being connected to body of the first transistor and body of the third transistor.