Level shift circuit with common mode level control

Details Level shift circuit with common mode level control Level shift circuit with common mode level control

1999-12-15

2001-09-18

Cunningham, Terry D. (Department: 2816)

Miscellaneous active electrical nonlinear devices, circuits, and

Specific signal discriminating without subsequent control

By amplitude

C327S067000, C327S063000

Reexamination Certificate

active

06292031

ABSTRACT:

TECHNICAL FIELD OF THE INVENTION
This invention relates to a level shift circuit, that is, a circuit which shifts the level of an input signal to a desired common mode signal level.
BACKGROUND OF THE INVENTION
Electronic circuits often need to have circuits which can alter the common mode level of signals. Purely as an example, in current mode logic (CML) circuits, voltages are typically referenced from the most positive supply voltage. However, an analog circuit connected to such a digital CML circuit may need to have its threshold voltages referenced to the negative supply. As a result, at the digital/analog interface, there is a need for a circuit which shifts the signal level between the two voltage supply rails.
More generally, there may be a need to shift the level of a signal to an arbitrary fixed or controllable level.
JP-A-6-260925 discloses a level shift circuit, in which first and second input terminals form a differential input, for receiving a differential input voltage, and are connected to the bases of first and second NPN transistors. The collector terminals of these transistors are connected together, and the emitter terminals are connected to respective output terminals which supply a differential output voltage. The emitters of these transistors are further connected through respective resistors to respective halves of a current mirror circuit. The common mode level of the output signals (i.e. the average of the signals) is determined by the values of components in the circuit, for example the resistance values of the resistors.
An object of the present invention is to provide a level shifting circuit which, in preferred embodiments, can provide a fixed output common mode level which is independent of the supply voltage and the input common mode voltage.
SUMMARY OF THE INVENTION
According to embodiments of the present invention, there is provided a level shift circuit which has a differential input, for receiving input signals, and a differential output, for supplying output signals derived from the input signals. The level shift circuit further includes a control level setting input, and a feedback circuit for setting a common mode level of the output signals to a level set on the control level setting input.


REFERENCES:
patent: 3491307 (1970-01-01), Solomon et al.
patent: 3582802 (1971-06-01), Weekes
patent: 4105942 (1978-08-01), Henry
patent: 4345213 (1982-08-01), Schade, Jr.
patent: 4555457 (1985-11-01), Dhanji
patent: 4560921 (1985-12-01), Yamatake
patent: 4697152 (1987-09-01), Westwick
patent: 4701719 (1987-10-01), Nagata
patent: 4725790 (1988-02-01), Addis et al.
patent: 4749956 (1988-06-01), Torelli et al.
patent: 4906943 (1990-03-01), Koch
patent: 4918399 (1990-04-01), Devecchi et al.
patent: 5008632 (1991-04-01), Sutterline
patent: 5182477 (1993-01-01), Yamaski et al.
patent: 5283535 (1994-02-01), Sevenhans et al.
patent: 5334948 (1994-08-01), Fong et al.
patent: 5428316 (1995-06-01), Molnar
patent: 5568089 (1996-10-01), Maru
patent: 5604464 (1997-02-01), Hwang et al.
patent: 5825819 (1998-10-01), Cogburn
patent: 5990743 (1999-11-01), Gabara
patent: 0 493 335 A1 (1992-07-01), None
patent: 0 516 423 a1 (1992-12-01), None
patent: 0 639 889 A1 (1995-02-01), None
patent: 0 840 442 A1 (1998-05-01), None
patent: 2 135 548 A (1984-08-01), None
patent: WO 91/07814 (1991-05-01), None
patent: WO 97/05696 (1997-02-01), None

Affiliated with

Also associated with

Rating

Level shift circuit with common mode level control does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Level shift circuit with common mode level control, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Level shift circuit with common mode level control will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2473835