Browse Prior Art Database

Bipolar to MOSFET Level Converter Circuit

IP.com Disclosure Number: IPCOM000090243D
Original Publication Date: 1969-Mar-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 22K

Publishing Venue

IBM

Related People

Martin, LC: AUTHOR

Abstract

The interface between discrete bipolar transistor circuits and integrated MOSFET transistor circuits has presented a problem in level conversion. Heretofore, circuits using discrete components have been employed to convert the bipolar logic voltage levels to MOSFET logic voltage levels. The circuit to be described below achieves level conversion with maximum voltage stability by using a MOSFET circuit to achieve the desired conversion.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 66% of the total text.

Page 1 of 2

Bipolar to MOSFET Level Converter Circuit

The interface between discrete bipolar transistor circuits and integrated MOSFET transistor circuits has presented a problem in level conversion. Heretofore, circuits using discrete components have been employed to convert the bipolar logic voltage levels to MOSFET logic voltage levels. The circuit to be described below achieves level conversion with maximum voltage stability by using a MOSFET circuit to achieve the desired conversion.

A bipolar logic level signal is applied to input 1 of MOSFET 2. The output 5 of MOSFET 2 is connected to voltage source V2 through resistor 4. V2 supplies voltage at the MOSFET logic level. The substrate 8 of MOSFET 2 is connected to V1 which is the collector supply for the bipolar circuits. Gate 3 of MOSFET 2 is biased by an automatic threshold compensation network which is connected between V1 and V2 and includes MOSFET 7, resistor 6, and constant current source 9. Because the threshold voltage of MOSFET transistors is normally defined at 10 microamperes, the selection of a 10 microampere source 9 sets the source to drain voltage of MOSFET 7 at the threshold voltage. MOSFET 7 and transistor 6 maintain the voltage at gate 3 of MOSFET 2 at a fixed voltage with respect to the threshold voltage. Since MOSFET's 2 and 7 are both on the same chip, their threshold voltages are no more than 200 millivolts apart in the worst case. A variation of threshold voltage of this magnitude is not sufficient...