Texas Instruments Corporation

National Semiconductor Corporation

Eric Paul Lindgren

Jayawardan Janardhanan

Sinjeet Parekh

Christopher Andrew Schell

Benyong Zhang

Henry Yao

Arvind Sridhar

Chee Peng Ong

Wen Hui Woon

A selection circuit receives a plurality of reference clocks. The selection circuit is controlled by a control signal to output one of the plurality of reference clocks. A phase-locked loop couples to an output of the selection circuit and uses the selected reference clock for phase locking an output clock. A plurality of reference clock window detector circuits is included. Each reference clock window detector circuit receives a separate reference clock. Each reference clock window detector circuit asserts an error signal responsive to an early reference clock edge error in which the reference clock window detector circuit detects a reference clock edge before expiration of an early time window. Further, each reference clock window detector circuit asserts the error signal responsive to a late reference clock edge error in which the reference clock window detector circuit detects a reference clock edge after expiration of a late time window.

Corrupted clock detection circuit for a phase-locked loop

A circuit includes a time-to-digital converter (TDC) to produce an output signal that is a function of a time difference between a first input clock to the TDC and a second input clock to the TDC. A first delay line is also included to add a time delay to a third clock to produce the first input clock. A pseudo random binary sequence generator generates a pseudo random binary bit sequence to be used to vary the amount of time delay added by the first delay line to the third clock.

Wobble reduction in an integer mode digital phase locked loop

A phase-locked loop (PLL) includes a selection circuit including a plurality of inputs, each input to receive a separate reference clock. A programmable reference clock divider divides down the reference clock selected by the selection circuit to generate a divided down reference clock. A feedback clock divider divides down an output clock from the PLL to generate a feedback clock. A time-to-digital converter (TDC) generates a digital output value based on a phase difference between the divided down reference clock and the feedback clock. A circuit including a finite state machine, causes, responsive to an indication to change reference clocks, the reference clock divider and the feedback clock divider to be held in a reset state, the divide ratio of the reference clock divider to be modified, and then to release the reset state.

Switch between input reference clocks of different frequencies in a phase locked loop (PLL) without phase impact

An electronic package having multiple pins may be tested in parallel for output short circuit current by simulating a direct short to ground by simultaneously connecting multiple output pins directly to ground in order to active a current limiter associated with each of the output pins. The pins are then connected to a resistive connection to ground via a set of resistors; the direct ground is then removed, such that the current limiter associated with each of the output pins remains activated. A voltage drop across each of the set of resistors is measured simultaneously. An output short circuit current fault is indicated when the voltage drop across any of the resistors exceeds a threshold value corresponding to a maximum output short circuit current value.

Testing integrated circuit packaging for output short circuit current

An integrated circuit (IC) with an oscillator and electrostatic discharge (ESD) protection in which the parasitic capacitance of the ESD protection circuitry is disassociated from the oscillator circuitry to minimize loading of the tank circuit thereby minimizing degradation of the tank circuit quality factor (Q).

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Bonney Lake, WA, United States of America

Eric Paul Lindgren