RAIL-TO-RAIL INPUT STAGE CIRCUIT WITH DYNAMIC BIAS CONTROL
First Claim
1. A rail-to-rail (R-R) input stage circuit operating over a rail-to-rail input common mode voltage range, comprising:
- a differential pair circuit, having a first input common mode voltage range, coupled to a level shifted differential pair, having a second input common mode voltage range to enable operation of the R-R input stage circuit over an input common mode voltage that extends from a negative power supply to a positive power supply; and
a first bias control circuit, coupled to the level shifted differential pair, to dynamically control the bias current of the level shifted differential pair when the input common mode voltage of the R-R input stage circuit is outside the second input common voltage range.
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Accused Products
Abstract
An improved rail-to-rail (R-R) input stage circuit with dynamic bias control is described. Input stage circuit includes a differential pair circuit, a level shifted differential pair and a bias control circuit. The differential pair circuit and the level shifted differential pair are of same type, non-complementary MOS devices. In exemplary embodiments, a first and a second bias control circuits dynamically control the bias current of the level shifted differential pair and the bias current of the differential pair circuit, respectively, in response to the input common mode voltage of the rail-to-rail input stage circuit. First and second bias control circuits maintain the output impedance of the R-R input stage circuit at a desired level, as the R-R input stage circuit operates outside the input common mode voltage range supported by the level shifted differential pair and the differential pair circuit, respectively. Further exemplary embodiments include a first and a second gm control circuits. Gm control circuits maintain the transconductance of the R-R input stage circuit substantially constant over the entire input common mode voltage range of the R-R input stage circuit.
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Citations
26 Claims
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1. A rail-to-rail (R-R) input stage circuit operating over a rail-to-rail input common mode voltage range, comprising:
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a differential pair circuit, having a first input common mode voltage range, coupled to a level shifted differential pair, having a second input common mode voltage range to enable operation of the R-R input stage circuit over an input common mode voltage that extends from a negative power supply to a positive power supply; and a first bias control circuit, coupled to the level shifted differential pair, to dynamically control the bias current of the level shifted differential pair when the input common mode voltage of the R-R input stage circuit is outside the second input common voltage range. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A rail-to-rail (R-R) input stage circuit operating over a rail-to-rail input common mode voltage range, comprising:
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a differential pair circuit, having a first input common mode voltage range, coupled to a level shifted differential pair, having a second input common mode voltage range to enable operation of the R-R input stage circuit over an input common mode voltage that extends from negative power supply to positive power supply; and first means, coupled to the level shifted differential pair, for dynamically controlling the bias current of the level shifted differential pair when the input common mode voltage of the R-R input stage circuit is outside of the second input common mode voltage range. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification