Level shifting and level-shifting amplifier circuits

• US 20050024087A1
• Filed: 09/02/2004
• Published: 02/03/2005
• Est. Priority Date: 07/19/2002
• Status: Active Grant

• Current Assignee: Guoxing Li, Liusheng Liu
• Original Assignee: Guoxing Li, Liusheng Liu
• Inventors: Li, Guoxing, Liu, Liusheng
• Granted Patent: US 6,930,515 B2
• Time in Patent Office: Days
• US Class Current: 326/80
• CPC Class Codes: H03K 19/018528 with at least one differential stage

Abstract

Level shifting and amplified level shifting circuit topologies are provided that include two or more level shifting or amplified level shifting circuits. The level shifting circuits receive a variable and fixed input and generate a variable and fixed output that are level shifted with respect to the input signals. The amplified level shifting circuits receive a variable and fixed input and generate a variable and fixed output that are level shifted and amplified with respect to the input signals. These circuits may be utilized to form a detection circuit that detects a difference in the output signals.

Claims

1. An amplified level shifting circuit topology comprising:

a first amplifying level shifting circuit capable of at least amplifying a variable input signal by a first gain factor greater than unity to provide an amplified and level shifted output signal; and

a second amplifying level shifting circuit capable of at least amplifying a fixed input reference signal by a second gain factor greater than unity to provide a fixed, amplified and level shifted output threshold signal, said amplified level shifting circuits being biased with respect to each other so that each has a DC transfer curve that is shifted with respect to the other.

2. The amplified level shifting circuit topology as claimed in claim 1, wherein said second amplifying level shifting circuit comprises:

a first branch circuit for level shifting said fixed input signal, said first branch further comprising a load resistor for determining a shift of said fixed input signal; and

,

a second branch circuit for amplifying said fixed input signal by said second gain factor.

3. The amplified level shifting circuit topology as claimed in claim 2, further comprising a bias circuit generating a bias voltage for biasing said first and second branch.

4. The amplified level shifting circuit topology as claimed in claim 1, wherein DC transfer curves are right shifted with respect to a supply voltage.

5. The amplified level shifting circuit topology as claimed in claim 1, wherein DC transfer curves are left shifted with respect to a supply voltage.

6. The amplified level shifting circuit topology as claimed in claim 1, wherein said DC transfer curves are shifted to be approximately in a middle of two supply voltages.

7. The amplified level shifting circuit topology as claimed in claim 1, further comprising a third amplifying level shifting circuit capable of at least amplifying said fixed input reference signal by a third gain factor greater than unity to provide a second fixed, amplified and level shifted output threshold signal, said first, second, and third amplified level shifting circuits being biased with respect to each other so that each has a DC transfer curve that is shifted with respect to the other.

8. A detection circuit comprising:

a first amplifying level shifting circuit capable of at least amplifying a variable input signal by a first gain factor greater than unity to provide an amplified and level shifted output signal;

a second amplifying level shifting circuit capable of at least amplifying a fixed input reference signal by a second gain factor greater than unity to provide a fixed, amplified and level shifted output threshold signal, said amplified level shifting circuits being biased with respect to each other so that each has a DC transfer curve that is shifted with respect to the other; and

a comparator capable of receiving said amplified and level shifted output signal and said fixed, amplified and level shifted output threshold signal and generating a signal indicative of a difference between said amplified and level shifted output signal and said fixed, amplified and level shifted output threshold signal.

9. The detection circuit as claimed in claim 8, wherein said second amplifying level shifting circuit comprises:

a first branch circuit for level shifting said fixed input signal, said first branch further comprising a load resistor for determining a shift of said fixed input signal; and

,

a second branch circuit for amplifying said fixed input signal by said second gain factor.

10. The detection circuit as claimed in claim 9, further comprising a bias circuit generating a bias voltage for biasing said first and second branch.

11. The detection circuit as claimed in claim 8, further comprising a third amplifying level shifting circuit capable of at least amplifying said fixed input reference signal by a third gain factor greater than unity to provide a second fixed, amplified and level shifted output threshold signal, said first, second, and third amplified level shifting circuits being biased with respect to each other so that each has a DC transfer curve that is shifted with respect to the other.

12. A method comprising:

amplifying a variable input signal by a first gain factor greater than unity, and shifting said variable input signal to provide an amplified and level shifted output signal from said variable input signal; and

amplifying a fixed input reference signal by a second gain factor greater than unity, and shifting said fixed input reference signal to provide a fixed, amplified and level shifted output threshold signal from said fixed input reference signal, said fixed, amplified and level shifted output threshold signal being shifted with respect to said amplified and level shifted output signal.

13. The method of claim 12, further comprising

comparing said amplified and level shifted output signal and said fixed, amplified and level shifted output threshold signal;

and

generating a signal representative of a difference between said amplified and level shifted output signal and said fixed, amplified and level shifted output threshold signal.

14. The method of claim 12, further comprising shifting said output signals up with respect to a supply voltage.

15. The method of claim 12, further comprising shifting said output signals down with respect to a supply voltage.

16. The method of claim 12, wherein said first and second gain factor are approximately equal.

17. The method of claim 12, further comprising amplifying said fixed input reference signal by a third gain factor greater than unity, and shifting said fixed input reference signal to provide a second fixed, amplified and level shifted output threshold signal from said fixed input reference signal, said second fixed, amplified and level shifted output threshold signal being shifted with respect to said amplified and level shifted output signal.