Programmable logic device transceiver architectures that facilitate using various numbers of transceiver channels together

1. Transceiver circuitry on a programmable logic device integrated circuit comprising:

a plurality of circuit modules, each of which includes:

(1) a plurality of channels of transceiver circuitry;

(2) a clock source circuit;

(3) a first clock signal distribution circuit extending from the clock source circuit to all of the channels in the module;

(4) a second clock signal distribution circuit extending to all of the channels in the module; and

(5) selection circuitry associated with each of the channels for allowing that channel to select a clock signal from either the first or second clock signal distribution circuit;

first routing circuitry for allowing either the first or second clock signal distribution circuit of each module to supply a signal to the second clock signal distribution circuit of a first adjacent one of the modules; and

second routing circuitry for allowing either the first or second clock signal distribution circuit of each module to supply a signal to the second clock signal distribution circuit of a second adjacent one of the modules.

2. The circuitry defined in claim 1 wherein the modules are disposed on the programmable logic device in a linear array, and wherein for each module the first and second adjacent modules are at respective opposite ends of said each module.

3. The circuitry defined in claim 1 wherein each of the first and second routing circuitries comprises:

buffering circuitry for buffering a signal passing through the routing circuitry.

4. The circuitry defined in claim 1 further comprising for each of the first and second routing circuitries:

a control signal source for controlling which routing allowed by that routing circuitry is actually implemented.

5. The circuitry defined in claim 4 wherein the control signal source is a programmable component of the programmable logic device integrated circuit.

6. The circuitry defined in claim 1 wherein each module includes one instance of each of the first and second routing circuitries.

7. Transceiver circuitry on a programmable logic device integrated circuit comprising:

a plurality of channels of transceiver circuitry that are grouped into several subpluralities of such channels;

a clock source circuit associated with each of the subpluralities;

first and second clock distribution circuitries associated with each of the subpluralities and each extending to all of the channels in the associated subplurality, the first clock distribution circuitry receiving a clock signal from the clock source circuit associated with that subplurality;

selection circuitry associated with each of the channels for allowing that channel to select a clock signal from either of the first and second clock distribution circuitries associated with the subplurality that includes that channel; and

routing circuitry associated with each of the subpluralities for allowing the second clock distribution circuitry associated with that subplurality to either receive a signal from either of the first and second clock distribution circuitries associated with either of two other subpluralities that are adjacent to that subplurality, or to supply a signal to the second clock distribution circuitry associated with either of those two other subpluralities.

8. The circuitry defined in claim 7 wherein the subpluralities are disposed on the programmable logic device in a linear array, and wherein for each subplurality the two other subpluralities are disposed at respective opposite ends of said each subplurality.

9. The circuitry defined in claim 7 wherein each of the routing circuitries includes:

buffering circuitry for buffering a signal passing through that routing circuitry.

10. The circuitry defined in claim 7 further comprising for each of the routing circuitries:

a control signal source for controlling which connection allowed by that routing circuitry is actually made.

11. The circuitry defined in claim 10 wherein the control signal source comprises programmable circuitry of the programmable logic device integrated circuit.

12. Transceiver circuitry on a programmable logic device comprising:

a plurality of channels of transceiver circuitry;

a plurality of clock source circuits distributed among the channels;

a first clock distribution circuit associated with each of the clock source circuits for distributing a clock signal from that clock source circuit to a subplurality of the channels that are adjacent to that clock source circuit;

a second clock distribution circuit associated with each of the first clock distribution circuits and coextensive therewith;

selection circuitry associated with each of the channels for allowing that channel to get a clock signal from either the first clock distribution circuit that distributes a clock signal to that channel or from the second clock distribution circuit that is associated with that first clock distribution circuit; and

routing circuitry for allowing each of the second clock distribution circuits to either supply a signal to either of two others of the second clock distribution circuits, or to receive a signal from either of those two others of the second clock distribution circuits or either of the first clock distribution circuits with which those two others of the second clock distribution circuits are associated.

13. The circuitry defined in claim 12 wherein the routing circuitry includes buffering circuitry for buffering a signal passing through the routing circuitry.

14. The circuitry defined in claim 12 wherein the routing circuitry is programmable with respect to the routing it performs.

15. The circuitry defined in claim 12 wherein each of the selection circuitries is programmable with respect to the selection that it makes.

16. The circuitry defined in claim 12 wherein each of the subpluralities includes four of the channels.

17. The circuitry defined in claim 16 wherein each of the subpluralities includes no more than four of the channels.