IMPROVED BIASING FOR A POWER MOSFET ACTING AS A SWITCH
Permalink
Bookmark
Share
Twitter
Digg
Reddit
Facebook
Stumbleupon
Del.icio.us| IP.com Number | IPCOM000006284D |
|
|
|---|---|---|---|
| Dated | Dec 1, 1991 UTC | ||
| Size | 1 page(s) (62.9 KB) | ||
| Disclosed by |
|
||
Publication Summary
It is often desirable to utilize a power MOSFET as a switch. However, in conventional techniques, such as biasing the power MOSFET with a voltage doubler con- figuration or through the use of a flyback drive circuit, problems are encountered. These problems manifest them- selves in a number of forms: first, there is a requirement to bias the gate electrode of the MOSFET at a higher potential than the source electrode in order to achieve a low drain-source resistance (rDSon) and, therefore, a reduction in the power consumption of the switch; and second, present circuit implementation is complicated. Furthermore, there is a demand within a power MOSFET switch circuit for a fast operational switching time. This requirement is particularly prominent when switching a MOSFET in a high frequency switched power supply.| Country | United States |
|---|---|
| Language | English (United States) |
| Related Person(s) |
(AUTHOR) Yitzak Cohen (AUTHOR) Rafael Brody (AUTHOR) Ofer Rosenzwieg (AUTHOR) Tzvika Magril |
| Copyright | Motorola Inc. December 1991 |
About this Publication
This document was submitted to IP.com's Prior Art Database and this preview is designed to provide you with information regarding the contents of this document by displaying up to the first four pages of the document as scaled page renderings and displaying a limited amount of text which was extracted from the document on the Text Preview Tab.
To find out more on how to obtain the entire document, click the Download tab. There is a charge for downloading some Prior Art Database documents; please examine carefully whether you believe this document fills your needs before purchasing.
For more information about the Prior Art Database, visit the Learn section of this website. Thank you for visiting IP.com's Prior Art Database! You may wish to check out our Global Patent Search website before you leave.
0 M
MOTOROLA /NC. Technical Developments Volume 14 December 1991
IMPROVED BIASING FOR A POWER MOSFET ACTING AS A SWITCH
by Yitzak Cohen, Rafael Brody, Ofer Rosenzwieg and Tzvika Magril
It is often desirable to utilize a power MOSFET as a switch. However, in conventional techniques, such as biasing the power MOSFET with a voltage doubler con- figuration or through the use of a flyback drive circuit, problems are encountered. These problems manifest them- selves in a number of forms: first, there is a requirement to bias the gate electrode of the MOSFET at a higher potential than the source electrode in order to achieve a low drain-source resistance (rDSon) and, therefore, a reduction in the power consumption of the switch; and second, present circuit implementation is complicated. Furthermore, there is a demand within a power MOSFET switch circuit for a fast operational switching time. This requirement is particularly prominent when switching a MOSFET in a high frequency switched power supply.
Figure 1 illustrates a power MOSFET switching cir- cuit with improved biasing characteristics.
An increased gate bias for power MOSFET Q2 is obtained through the use of additional low cost com- ponents D,, R,, R2, C, and Q,. When MOSFET Q, is at saturation, its drain terminal can be consid- ered to be at ground potential. In this state, capaci- tor C,, is charged to a voltage potential given by:
v (VDD - VDI]
source an& hence, a high gate voltage with respect to the source i...