1. An amplifier circuit having a circuit input and an circuit output, comprising:
first and second amplifiers cascaded together, each having an input and an output, the circuit input being coupled to the input of the first amplifier and the circuit output being coupled to the output of the second amplifier;
a first chopper having an input coupled to the circuit input and an output coupled to an input of a third amplifier, an output of the third amplifier being coupled to an input of a second chopper, the second chopper having an output coupled to a fourth amplifier coupled as an integrator with capacitive feedback, an output of the integrator being coupled to a sample and hold circuit, an output of the sample and hold circuit being coupled to an input of a fifth amplifier, an output of the fifth amplifier being coupled to combine with the output of the first amplifier as the input coupled to the second amplifier;
one or more first compensation capacitors coupled between the output of the second amplifier and the input of the second amplifier; and,
one or more second compensation capacitors coupled between the output of the second amplifier and the input to the integrator.
2. The amplifier of claim 1 wherein the second amplifier comprises a pair amplifiers cascaded together, and further comprising one or more third compensation capacitors coupled between the output of the second amplifier and the connection cascading the pair of amplifiers together.
3. The amplifier of claim 1 further comprised of an autozeroing circuit coupled to the third amplifier.
4. The amplifier of claim 3 further comprised of an autozeroing circuit coupled to the fourth amplifier.
5. The amplifier of claim 1 further comprised of an autozeroing circuit coupled to the fourth amplifier.
6. The amplifier of claim 1 wherein the amplifiers and capacitors are chosen to provide an amplifier circuit frequency response that is flat for low frequencies, and which rolls off at 6 dB per octave above the low frequencies.
7. The amplifier of claim 1 further comprising:
a third chopper coupled to receive a feedback responsive to the output of the second amplifier;
a sixth amplifier having an input coupled to output of the third chopper and an output coupled to combine with the output of the third amplifier as the input coupled to the second chopper; and
a seventh amplifier coupled to receive the feedback responsive to the output of the second amplifier and having an output coupled to combine with the output of the first amplifier.
8. The amplifier of claim 7 wherein the second amplifier comprises a pair amplifiers cascaded together, and further comprising one or more third compensation capacitors coupled between the output of the second amplifier and the connection cascading the pair of amplifiers together.
9. The amplifier of claim 7 further comprised of an autozeroing circuit coupled to the fourth amplifier.
10. The amplifier of claim 9 further comprised of an autozeroing circuit coupled to the third and sixth amplifiers.
11. The amplifier of claim 10 wherein the autozeroing circuit coupled to the third and sixth amplifiers includes matching autozeroing storage capacitors in series with the inputs to the third and sixth amplifiers.
12. The amplifier of claim 7 wherein the amplifiers and capacitors are chosen to provide an amplifier circuit frequency response that is flat for low frequencies, and which rolls off at 6 dB per octave above the low frequencies.
13. A method of reducing output offset and noise in the output of an amplifier circuit having an input and an output comprising:
providing a plurality of cascaded amplifiers coupled between the amplifier circuit input and amplifier circuit output,
amplifying the amplifier circuit input with a first chopper stabilized amplifier;
integrating an output of the first chopper stabilized amplifier;
sampling and holding an output of the integrator with a sample and hold circuit; and,
coupling a signal responsive to a signal held by the sample and hold circuit to the cascaded amplifiers after at least one stage of amplification by the cascaded amplifiers.
14. The method of claim 13 wherein a signal held by the sample and hold circuit is amplified or attenuated before being coupled to the cascaded amplifiers.
15. The method of claim 13 wherein the output of the first chopper stabilized amplifier is integrated over alternate full chopper cycles, and the sampling and holding of the output of the integrator occurs between the alternate full chopper cycles when the integrator is not integrating.
16. The method of claim 15 wherein an integrator amplifier and the first chopper stabilized amplifier are autozeroed between the alternate full chopper cycles when the integrator is not integrating and after the sampling and holding.
17. The method of claim 13 further comprising amplifying a feedback signal responsive to an output of the amplifier circuit and coupling the amplified feedback signal to the cascaded amplifiers after at least one stage of amplification, and amplifying the feedback signal with a second chopper stabilized amplifier and combining the amplified feedback signal with the output of the chopper first stabilized amplifier.
18. The method of claim 17 wherein a signal held by the sample and hold circuit is amplified before being coupled to the cascaded amplifiers.
19. The method of claim 17 wherein the combined output of the first and second chopper stabilized amplifiers is integrated over alternate full chopper cycles, and the sampling and holding of the output of the integrator occurs between the alternate full chopper cycles when the integrator is not integrating.
20. The method of claim 19 wherein an integrator amplifier and the first and second chopper stabilized amplifiers are autozeroed between the alternate full chopper cycles when the integrator is not integrating and after the sampling and holding.
21. The method of claim 19 wherein the inputs to the first and second chopper stabilized amplifiers are capacitively coupled inputs.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method for replicating a control packet in a forwarding plane of a network element, the control packet being destined for a plurality of subscriber end stations, wherein the method comprises:
receiving a message from a control plane that indicates the forwarding plane should add an identifier for one of the plurality of subscriber end stations to a list of outgoing interfaces for a multibind interface;
adding, in response to receiving the message, the identifier for the one of the plurality of subscriber end stations to the list of outgoing interfaces for the multibind interface;
receiving the control packet from the control plane, wherein the control plane generated the control packet;
detecting a replication indicator associated with the control packet;
determining the plurality of subscriber end stations, each of the plurality of subscriber end stations being associated with the control packet, wherein said determining includes looking up the list of outgoing interfaces for the multibind interface;
replicating the control packet for each of the plurality of subscriber end stations; and
distributing the replicated control packets to the plurality of subscriber end stations.
2. The method of claim 1, further comprising:
bypassing a reverse path forwarding check for each replicated control packet based on a presence of the replication indicator in association with the control packet.
3. The method of claim 1, wherein the control packet is addressed to a designated group address that indicates replication is required based on the designated group address.
4. The method of claim 1, further comprising:
receiving a set of packet metadata in association with the control packet, wherein the set of packet metadata includes a replication flag as the replication indicator.
5. The method of claim 1, wherein the control packet is a general query for an Internet group management protocol (IGMP) group.
6. A network element, to be coupled with a plurality of subscriber end stations through an access network, configured to replicate a control packet meant for the plurality of subscriber end stations, wherein the plurality of subscriber end stations are to be bound to a multibind interface of the network element, the network element comprising:
a control plane comprising:
a packet generation module configured to:
generate the control packet, wherein the control packet is to be replicated and distributed at a forwarding plane, and
generate a set of metadata in association with the control packet that includes a replication indicator and a control message route identification information, and
a communication module configured to distribute the control packet and the set of metadata to the forwarding plane; and
the forwarding plane, coupled with the control plane, comprising a plurality of line cards that each service one or more circuits bound to the multibind interface, wherein each line card is configured to include a list of circuit identifiers in association with the control message route identification information, and wherein the list of circuit identifiers includes at least identifiers the for circuits it handles that are bound to the multibind interface, wherein the plurality of line cards is configured to:
receive the control packet and the set of metadata from the control plane,
detect the replication indicator,
in response to detecting the replication indicator, determine a plurality of subscriber end station identifiers based on the control message route identification information,
replicate the control packet for each of the plurality of subscriber end station identifiers, and
distribute the replicated control packets to the plurality of subscriber end stations using the plurality of subscriber end station identifiers.
7. The network element of claim 6, wherein the forwarding plane is further configured to bypass a reverse path forwarding check for each replicated control packet based on a presence of the replication indicator in association with the control packet.
8. The network element of claim 6, wherein the control message route identification information includes a source address associated with the multibind interface and a group address associated with an application running in the packet generation module.
9. The network element of claim 6, wherein the packet generation module is further configured to run an Internet group management protocol (IGMP) group management application.
10. A tangible non-transitory machine-readable storage medium comprising instructions for a microprocessor of a forwarding plane, which, when executed by the microprocessor, cause the microprocessor to perform operations comprising:
receiving a message from a control plane that indicates the forwarding plane should add an identifier for one of a plurality of subscriber end stations to a list of outgoing interfaces for a multibind interface;
adding, in response to receiving the message, the identifier for the one of the plurality of subscriber end stations to the list of outgoing interfaces for the multibind interface;
receiving a control packet from the control plane, wherein the control plane generated the control packet;
detecting a replication indicator associated with the control packet;
determining the plurality of subscriber end stations, each of the plurality of subscriber end stations being associated with the control packet;
replicating the control packet for each of the plurality of subscriber end stations; and
distributing the replicated control packets to the plurality of subscriber end stations.
11. The tangible non-transitory machine-readable storage medium of claim 10, wherein the operations further comprise:
bypassing a reverse path forwarding check for each replicated control packet based on a presence of the replication indicator in association with the control packet.
12. The tangible non-transitory machine-readable storage medium of claim 10, wherein the control packet is addressed to a designated group address that indicates replication is required based on the designated group address.
13. The tangible non-transitory machine-readable storage medium of claim 10, wherein the operations further comprise:
receiving a set of packet metadata in association with the control packet and wherein the set of packet metadata includes a replication flag as the replication indicator.
14. The tangible non-transitory machine-readable storage medium of claim 10, wherein the control packet is a general query for an Internet group management protocol (IGMP) group.