Miscellaneous active electrical nonlinear devices – circuits – and – Signal converting – shaping – or generating – Particular stable state circuit
Patent
1995-02-13
1996-06-18
Callahan, Timothy P.
Miscellaneous active electrical nonlinear devices, circuits, and
Signal converting, shaping, or generating
Particular stable state circuit
327203, 327215, 327225, H03K 3037, H03K 3356
Patent
active
055281850
ABSTRACT:
A comparator produces a digital output based upon a differential input signal and hysteresis. To inject positive feedback, a second differential pair is added. This feedback pair is nominally identical to the input pair. If the comparator has recently sensed a positive input of sufficient magnitude to drive the comparator output high, switches are turned on coupling a positive hysteresis voltage to the inputs of the feedback differential pair. By coupling a fixed current differential from the second differential pair to the input differential pair, the effective switching threshold of the comparator is changed. A non-overlapping clock generator is formed so that the switches will not turn on simultaneously so as to short the hysteresis reference voltage source. The hysteresis voltage source can be centered at any voltage that does not exceed the common mode range of the input pair. In a first alternative embodiment, the ratio of feedback is not unity, such that the hysteresis voltage is linearly related to the noise margin. In a second alternative embodiment, a more complicated switch matrix can be used to provide a variety of different hysteresis voltage levels. By including a more complicated switch matrix having several taps, the level of hysteresis can be made programmable. In a third alternative embodiment, the comparator structure according to the present invention is translated so that the differential pairs are formed with p-channel transistors. In a fourth alternative embodiment, the programmable hysteresis is applied to a sense amplifier.
REFERENCES:
patent: 4670671 (1987-06-01), DeWeck
patent: 4717838 (1988-01-01), Brehmer et al.
patent: 4777388 (1988-10-01), Widener
patent: 4810908 (1989-03-01), Suzuki et al.
patent: 4940907 (1990-07-01), Laude
patent: 4963772 (1990-10-01), Dike
patent: 5003513 (1991-03-01), Porter et al.
patent: 5039888 (1991-08-01), Bell et al.
patent: 5329173 (1994-07-01), Murakami et al.
patent: 5367211 (1994-11-01), Giordano et al.
patent: 5369319 (1994-11-01), Good et al.
Sackinger, Edward and Guggenbuhl, Walter, A Versatile Building Block: The CMOS Differential Difference Amplifier, IEEE Journal of Solid-State Circuits, vol. SC-22, No. 2, Apr. 1987.
Allen and Holberg, CMOS Analog Circuit Design, New York: Holt Rinehard and Wilson, pp. 349-356, 1987.
Lewicki Laurence D.
Opris Ion E.
Callahan Timothy P.
National Semiconductor Corporation
Nu Ton My-Trang
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