US 8,411,804 B2Granted

Digital demodulation of pulse-width modulated signals

AssigneeTexas Instruments Incorporated

InventorsKarthik Subburaj, Anant Shankar Kamath, Jayawardan Janardhanan

Life of this patent

Estimating the term…

Loading patent…

Abstract

A digital PWM demodulator includes a first set of delay cells to receive a PWM signal and to propagate the PWM signal in a forward direction for a first interval. Delayed signals obtained at the end of the first interval are propagated in the reverse direction through the delay cells for a second interval. A logic zero feeds into the last cell at the start of the second interval. The output of a last cell in the delay cells at the end of the second interval is indicative of a data value modulated on the PWM signal. The digital PWM demodulator includes a second set of delay cells designed to operate identical to the first set of delay cells. The first set of delay cells and the second set of delay cells in conjunction with additional digital circuitry demodulate alternate periods of the PWM signal.

Claims17

Dependent claims

A receiver comprising:

a first plurality of delay cells coupled in a series arrangement,
wherein each delay cell in the first plurality of delay cells is designed to provide a corresponding delay to a corresponding input signal, the first plurality of delay cells operable to propagate a pulse-width modulated (PWM) signal in a forward direction for a duration of a first interval to generate, at the end of the first interval, a first plurality of delayed signals,
wherein the first plurality of delay cells is operable to propagate the first plurality of delayed signals and a logic zero signal in a reverse direction for a duration of a second interval to generate, at the end of the second interval, a second plurality of delayed signals including a feedback signal,
wherein the feedback signal is an output of a last delay cell when the first plurality of delay cells is configured in the reverse direction,
wherein the logic zero signal is an input to a first delay cell in the series arrangement when the first plurality of delay cells is configured in the reverse direction;
and
a first flip-flop coupled to receive the feedback signal on a reset terminal, the first flip-flop being coupled to receive the PWM signal on a clock terminal,
wherein an output of the first flip-flop at the end of the second interval specifies a value of a data modulated on the PWM signal for an interval from the start of the first interval to the end of the second interval.

5 more elements

A method of demodulating a pulse-width modulated (PWM) signal, the method being performed in a receiver, the method comprising:

configuring, at the start of a first interval, a plurality of delay cells in a first series configuration for a duration of the first interval;
propagating the PWM signal through the plurality of delay cells configured in the first series configuration, wherein the propagating generates a first plurality of delayed signals at the end of the first interval;
reconfiguring, at the start of a second interval, the plurality of delay cells in a second series configuration for a duration of the second interval, wherein the second interval immediately follows the first interval;
propagating the first plurality of delayed signals and a logic zero signal through the plurality of delay cells configured in the second series configuration to generate a second plurality of delayed signals including a feedback signal, the feedback signal being the output of the last one of the delay cells in the second series configuration, wherein a last one of the delay cells in the first series configuration receives the logic zero signal as an input when the plurality of delay cells is configured in the second series configuration;
and
examining, at the end of the second interval, a logic level of the feedback signal,
wherein a logic level of the feedback signal determined by the examining specifies a data that the PWM signal is modulated by in an interval from the start of the first interval to the end of the second interval.

4 more elements

Dependencies are inferred from the claim text.