On-chip regulator with variable load compensation
An integrated circuit includes a voltage regulator to supply a regulated voltage and a data output that couples to an unterminated transmission line. The circuit draws a variable amount of power from the voltage regulator according to the data. The voltage regulator includes a first current generation circuit to provide a data transition-dependent current.
1. A transmitter integrated circuit comprising:
a voltage regulator to supply a regulated voltage;
an equalizing output driver circuit for transmitting data at a signal swing corresponding to the regulated voltage and a load current;
wherein the voltage regulator comprises a feedback current source coupled to the equalizing output driver circuit to provide a closed-loop current to the driver at a constant level based on an expected current for transmission of a non-equalization signal, and wherein the voltage regulator further comprises a feed-forward current source coupled to the equalizing output driver circuit in parallel with the feedback current source, the feed-forward current source responsive to an equalization signal input to selectively supply a calibrated current for summation with the closed-loop current at the equalizing output driver circuit.
2. The transmitter integrated circuit according to claim 1 wherein the calibrated current is based on a known change in an output impedance of the equalizing output driver circuit resulting from an anticipated transmission of an equalization signal.
3. The transmitter integrated circuit according to claim 1 , further comprising:
storage to store a value corresponding to the calibrated current.
4. The transmitter integrated circuit according to claim 3 , wherein:
the storage comprises a programmable register.
5. The transmitter integrated circuit according to claim 1 , wherein the equalizing output driver circuit comprises:
a main tap and a post tap.
6. The transmitter integrated circuit according to claim 5 , wherein:
the post tap is coupled to the main tap in a positive polarity configuration.
7. The transmitter integrated circuit according to claim 5 , wherein:
the post tap is coupled to the main tap in a negative polarity configuration.
8. A transmitter circuit comprising:
a driver circuit to transmit data during a normal operation mode; and
a voltage regulator to provide a regulated voltage for the driver circuit, the voltage regulator including
a source of a calibrated load current, wherein the source of calibrated load current provides current at a level determined while operating the voltage regulator out of the normal operation mode and in a calibration mode, and based on one or more known load parameters; and
a source of supplemental current based on at least one data dependent loading condition.
9. The transmitter circuit according to claim 8 , wherein the data dependent loading condition comprises at least one of an equalization event or a change in load impedance.
10. The transmitter circuit according to claim 8 wherein:
the source of a calibrated load current comprises a closed-loop feedback path including a first current source; and
the source of supplemental current comprises an open-loop path including a second current source and storage to store a setting corresponding to the supplemental current.
11. The transmitter circuit according to claim 10 wherein:
the storage comprises a programmable register.
12. The transmitter circuit according to claim 10 wherein:
the second current source selectively provides the supplemental current based on an input data sequence.
13. The transmitter circuit according to claim 12 wherein the supplemental current is provided in response to the input data sequence including an equalization event.
14. The transmitter circuit according to claim 8 wherein the driver circuit comprises one from the group comprising a single-ended driver circuit, a differential driver circuit, or a main/equalizing driver circuit.
15. An integrated circuit comprising:
a voltage regulator to supply a regulated voltage;
a circuit to process data, the circuit having an output for coupling to an unterminated transmission line, the circuit drawing a variable amount of power from the voltage regulator according to transitions in the data;
wherein the voltage regulator comprises an open-loop current generation circuit to provide a data transition-dependent current.
16. The integrated circuit of claim 15 wherein the open-loop current generation circuit includes a control input responsive to a control signal to generate current during rising-edge transitions in the data.
17. The integrated circuit of claim 15 wherein the open-loop current generation circuit includes a control input to generate current during rising edge and falling edge transitions in the data.
18. The integrated circuit of claim 15 and further including:
a closed-loop current generation circuit to provide a drift-dependent current to compensate for operational drift in at least one parameter from the group including timing, voltage and current.
19. The integrated circuit according to claim 15 wherein the open-loop current generation circuit includes pulse-width-modulation logic.
20. The integrated circuit according to claim 19 wherein the pulse-width-modulation logic produces a first pulse edge triggered by a data transition, and a second pulse edge dependent upon an adjustable delay relative to the data transition.