System and method for providing a fast turn on bias circuit for current mode logic transmitters
First Claim
1. A fast turn on bias circuit capable of being coupled to a gate of a bias transistor, said fast turn on bias circuit capable of providing a value of capacitance to said gate of said bias transistor to compensate for a Miller coupling capacitance in said bias transistor, said fast turn on bias circuit comprising:
- a capacitor having an output capable of being coupled to said gate of said bias transistor; and
a charge switch circuit coupled to an input of said capacitor.
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Abstract
A system and method is disclosed for providing a fast turn on bias circuit that permits a fast transition from an idle “power down” state to an active “power up” state in current mode logic (CML) transmitter output circuits. The invention comprises a capacitor coupled to a bias transistor and a charge switch circuit for controlling the operation of the capacitor. The capacitor has a value of capacitance that is equal in magnitude and opposite in sign to the Miller coupling capacitance in the bias transistor. The capacitor compensates for the Miller coupling capacitance within the bias transistor in less than ten nanoseconds. This permits a CML transmitter to more quickly restart the transmission of data after an active state has been initiated.
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Citations
24 Claims
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1. A fast turn on bias circuit capable of being coupled to a gate of a bias transistor, said fast turn on bias circuit capable of providing a value of capacitance to said gate of said bias transistor to compensate for a Miller coupling capacitance in said bias transistor, said fast turn on bias circuit comprising:
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a capacitor having an output capable of being coupled to said gate of said bias transistor; and a charge switch circuit coupled to an input of said capacitor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A common mode logic (CML) transmitter output circuit comprising a bias transistor and a fast turn on bias circuit capable of being coupled to a gate of said bias transistor, said fast turn on bias circuit capable of providing a value of capacitance to said gate of said bias transistor to compensate for a Miller coupling capacitance in said bias transistor, said fast turn on bias circuit comprising:
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a capacitor having an output capable of being coupled to said gate of said bias transistor; and a charge switch circuit coupled to an input of said capacitor. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A fast turn on bias circuit capable of being coupled to a gate of a bias transistor, said fast turn on bias circuit capable of providing a plurality of values of capacitance to said gate of said bias transistor to compensate for a Miller coupling capacitance in said bias transistor, said fast turn on bias circuit comprising:
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a plurality of capacitors of different values, each of said plurality of capacitors having an output capable of being coupled to said gate of said bias transistor; and a charge switch circuit coupled to an input of each of said plurality of capacitors. - View Dependent Claims (20, 21, 22, 23, 24)
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Specification