Oscillators – Ring oscillators
Patent
1999-07-22
2000-11-07
Grimm, Siegfried H.
Oscillators
Ring oscillators
324617, 324633, 327265, 365201, 368118, 368120, 371 214, G01R 2728, G04F 1002, H03B 502, H03H 1126
Patent
active
061442623
ABSTRACT:
A circuit measures a signal propagation delay through a series of memory elements on a programmable logic device. In one embodiment, a number of latches are configured in series. Each latch is initialized to store a logic zero. The first latch is then clock-enabled so that the output of the latch rises to a logic one. The logic one from the first latch clock-enables the second latch in the series so that the output of the second latch rises to a logic one, which in turn enables the next latch in the series. The time required for a rising edge to traverse the entire sequence of latches is the cumulative time required for the output of each latch to change in response to a clock-enable signal. Consequently, the delay through the series of latches provides a measure of the time required for one of the latches to respond to a clock-enable signal. In another embodiment, the latches are arranged in a loop so that the sequence of latches forms a ring oscillator, the period of which provides an indication of the time required for the latches to respond to clock-enable signals. Other embodiments include sequences of flip-flops arranged as delay elements or ring oscillators. Those embodiments provide means for measuring the time required for flip-flops to respond to preset or clear signals.
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Behiel, Esq. Arthur J.
Grimm Siegfried H.
Xilinx , Inc.
Young Edel M.
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