Internal jitter tolerance tester with an internal jitter generator
Exemplary embodiments of the present invention relate to an internal jitter tolerance tester. The internal jitter tolerance tester may include a digital loop filter consisting of a cyclic accumulator which accumulates a phase detector's output, a gain multiplier, an internal accumulated jitter generator (or an internal sinusoid jitter generator), and a phase rotator (or DCO) controller. The internal accumulated jitter generator may include a PRBS generator, a digital loop filter, an accumulator, and a gain controller. The accumulated jitter generator also may be replaced with the internal sinusoid jitter generator. The internal sinusoid jitter generator may include a counter, a sinusoid jitter profile lookup table, and a gain controller.
1. An internal jitter tolerance tester with an internal jitter generator, the jitter tolerance tester comprising:
a loop filter with a predetermined gain and a predetermined delay;
an internal accumulated jitter generator to generate an accumulated jitter and output the generated accumulated jitter to a gain multiplier;
the gain multiplier to be connected to an output of the loop filter and be connected to an output of the internal accumulated jitter generator; and
a phase rotator controller to be connected to an output of the gain multiplier and to generate a jitter-equipped clock signal,
wherein the internal accumulated jitter generator comprises,
a pseudorandom binary sequence (PRBS) generator to generate 1 and −1 randomly;
a subsequent accumulator to be connected to an output of the pseudorandom binary sequence generator and accumulate a random signal;
a lowpass filter to be connected between the pseudorandom binary sequence generator or be connected to an output of the subsequent accumulator, the lowpass filter eliminating a high frequency spur and a quantization noise; and
a gain controller to be connected to an output of the subsequent accumulator or be connected to an output of the lowpass filter, the gain controller controlling an amount of the accumulated jitter.
2. An internal jitter tolerance tester with an internal jitter generator, the jitter tolerance tester comprising:
a loop filter with a predetermined gain and a predetermined delay;
an internal sinusoid jitter generator to generate a sinusoid jitter and output the generated sinusoid jitter to a gain multiplier;
the gain multiplier to be connected to an output of the loop filter and be connected to an output of the sinusoid jitter generator; and
a phase rotator controller to be connected to an output of the gain multiplier and to generate a jitter-equipped clock signal,
wherein the sinusoid jitter generator comprises,
a counter to select a frequency of a jitter from a sinusoid jitter profile lookup table; and
a gain controller to be connected to an output of the counter and control an amplitude of the jitter.
3. An internal jitter tolerance tester with a DCO (digitally controlled oscillator), the jitter tolerance tester comprising:
a loop filter with a predetermined gain and a predetermined delay;
an internal accumulated jitter generator to generate an accumulated jitter and output the generated sinusoid jitter to a gain multiplier;
the gain multiplier to be connected to an output of the loop filter and be connected to an output of the internal accumulated jitter generator; and
a DCO to be connected to an output of the gain multiplier,
wherein the internal accumulated jitter generator comprises,
a PRBS generator to generate 1 and −1 randomly;
a lowpass filter to be connected to an output of the PRBS generator and eliminate a high frequency spur and a quantization noise; and
a gain controller to be connected to an output of the lowpass filter and control an amount of the accumulated jitter
wherein, the DCO accumulates the accumulated jitter.