High-speed digital multiplexer
View Patent ↗A high-speed digital multiplexer is disclosed. The multiplexer includes a plurality of input pins for receiving a plurality of digital input signals and switching circuitry coupled to the input pins. The switching circuitry has respective outputs coupled to a common node and is operative to enable a selected one of the plurality of input pins. The multiplexer further includes a local signal converter having a circuit branch set to a common voltage. The branch is connected to the common node to sense changes in current corresponding to an input signal received by an enabled input pin. An output pin is coupled to the local signal converter, whereby the local signal converter is operative to produce voltage changes at the output corresponding to the sensed current changes.
1. A high-speed digital multiplexer including:
a plurality of input pins for receiving a plurality of digital input signals;
switching circuitry coupled to the input pins, the switching circuitry having respective outputs coupled to a common node, the switching circuitry operative to enable a selected one of the plurality of input pins;
a transresistance amplifier having a circuit branch set to a common voltage, the branch connected to the common node to sense changes in current corresponding to an input signal received by an enabled input pin; and
an output pin coupled to the transresistance amplifier, whereby the transresistance amplifier is operative to produce voltage changes at the output corresponding to the sensed current changes.
2. A high-speed digital multiplexer according to claim 1 wherein the switching circuitry comprises:
a plurality of semiconductor switches, the plurality of semiconductor switches corresponding to the plurality of input pins.
3. A high-speed digital multiplexer according to claim 2 wherein the plurality of semiconductor switches comprises a plurality of diodes.
4. A high-speed digital multiplexer according to claim 1 wherein the transresistance amplifier includes:
a base terminal fixed to a constant voltage;
an emitter branch coupled to the common node; and
a collector terminal tied to the output pin.
5. A high-speed digital multiplexer according to clam 1 wherein the switching circuitry is operative to enable the selected one of the plurality of input pins based on the selected one of the plurality of input pins having a lower first voltage than non-selected ones of he plurality of input pins.
6. A high-speed digital multiplexer according to claim 5 wherein the common voltage is higher than the first voltage and at least one voltage of the non-selected ones of the plurality of input pins is higher than the common voltage.
7. A high-speed digital multiplexer for use with a device-interface-board, the device-interface-board adapted for coupling to automatic test equipment, the multiplexer including:
a plurality of input pins adapted for coupling to a plurality of automatic test equipment channels;
switching circuitry coupled to the input pins, the switching circuitry having respective outputs coupled to a common node, the switching circuitry operative to enable a selected one of the plurality of input pins;
a local signal converter having a circuit branch set to a common voltage, th branch connected to the common node to sense changes in current corresponding to input signal received by art enabled input pin;
an output pin coupled to the local signal converter, whereby the local signal converter is operative to produce voltage changes at the output corresponding to the sensed current changes; and
wherein the switching circuitry is operative to enable the selected one of plurality of input pins based on the selected one of the plurality of input pins having a lower first voltage than non-selected ones of the plurality input pins.
8. A high-speed digital multiplexer according to claim 7 wherein the switching circuitry comprises:
a plurality of semiconductor switches, the plurality of semiconductor switches corresponding to the plurality of input pins.
9. A high-speed digital multiplexer according to claim 8 wherein the plurality of semiconductor switches comprises a plurality of diodes.
10. A high-speed digital multiplexer according to claim 7 wherein the local signal converter comprises:
a transresistance amplifier.
11. A high-speed digital multiplexer according to claim 10 wherein the transresistance amplifier includes:
a base terminal fixed to a constant voltage;
an emitter branch coupled to the common node; and
a collector terminal tied to the output pin.
12. A high-speed digital multiplexer according to claim 7 wherein the common voltage is higher than the first voltage and at least one voltage of the non-selected ones of he plurality of input pins is higher than the common voltage.
13. A device-interface-board for calibration/validation of automatic test equipment, the device-interface-board including:
at least one test socket adapted for receiving a device-under-test; and
a high-speed digital multiplexer for selectively passing tester signals from the automatic test equipment to the test socket, the multiplexer including
a plurality of input pins adapted for coupling to a plurality of automatic test equipment channels,
switching circuitry coupled to the input pins, the switching circuitry having respective outputs coupled to a common node, the switching circuitry operative to enable a selected one of the plurality of input pins,
a transresistance amplifier having a circuit branch set to a common voltage, the branch connected to the common node to sense changes in current corresponding to an input signal received by an enabled input pin, and
an output pin coupled to the transresistance amplifier, whereby transresistance amplifier is operative to produce voltage changes at the output corresponding to the sensed current changes.
14. A device-interface-board according to claim 13 wherein the switching circuitry comprises:
a plurality of semiconductor switches, the plurality of semiconductor switches corresponding to the plurality of input pins.
15. A device-interface-board according to claim 14 wherein the plurality of semiconductor switches comprises a plurality of diodes.
16. A device-interface-board according to claim 13 wherein the transresistance amplifier includes:
a base terminal fixed to a constant voltage;
an emitter branch coupled to the common node; and
a collector terminal tied to the output pin.
17. A device-interface-board according to claim 13 wherein the switching circuitry is operative to enable the selected one of the plurality of input pins based on the selected one of the plurality of input pins having a lower first voltage then non-selected ones of the plurality of input pins.
18. A device-interface-board according to claim 17 wherein the common voltage is higher then the first voltage and at least one voltage of the non-selected ones of the plurality of input pins is higher than the common voltage.