Miscellaneous active electrical nonlinear devices – circuits – and – Specific signal discriminating without subsequent control – By amplitude
Reexamination Certificate
1998-09-25
2001-10-23
Tran, Toan (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Specific signal discriminating without subsequent control
By amplitude
C327S096000, C327S063000
Reexamination Certificate
active
06307406
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to current comparators, particularly to a current comparator which makes use of cross-coupled current copiers to perform two comparisons of the reference and the signal currents.
2. Description of the Prior Art
Recently, current mode circuits have been the subject of much research. This is due to their potential to operate faster that their equivalent voltage mode circuits and the fact than the voltage swing on the internal nodes is small. Thus, current mode circuits tend to generate less noise than their voltage counterparts and can be used in applications with lower supply voltages.
A number of current mode ADCs have been designed and published in the prior art. The central comparison performed in these ADCs is to use current mirrors or current copiers to supply the reference and signal currents. A current to voltage conversion is carried out at the high output impedance of the current mirrors or current copiers, followed by some voltage detection and amplification.
However, these prior art comparators suffer from the significant drawback that in these systems one of the mirrors is connected to the power supply, while the other is connected to the ground supply. Consequently, any noise present on one of the supplies but not the other may affect the comparison, reducing the efficiency of the circuit.
An improved current comparator is therefore needed which significantly reduces the supply noise rejection problem while maximizing the overall gain of the circuit.
SUMMARY OF THE INVENTION
The present invention is directed to an integrated circuit which includes a current supply circuit for supplying a reference current and a signal current; at least one current copier circuit for creating a copy of the reference current and a copy of the signal current; an amplifing circuit connected to the current supply circuit and the current copier circuit. The amplifying circuit is configured with the current copier circuit to compare the copy of the reference current to the signal current and to compare the copy of the signal current to the reference current and to generate a comparison signal based upon these comparisons. The present invention also includes an output circuit connected to the amplifying circuit for receiving the comparison signal and generating an output signal and a current mode circuit for receiving the output signal from the output circuit.
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Lucent Technologies - Inc.
Nguyen Hai L.
Schnader Harrison Segal & Lewis LLP
Tran Toan
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