| 摘要 |
A delay limit detect circuit can determine the delay of a current steering delay cell, like those utilized in a voltage controlled oscillator (VCO), by monitoring a current (ISENSE) that tracks a delay cell current (I2). When the monitored current (ISENSE) outside of a limit, a signal LIMIT can be activated. A monitored current (ISENSE) can be generated by a control replica circuit having the same circuit component types as a control circuit within a delay cell. Such limit detection can provide a way to prevent a ring VCO from entering a runaway state, particularly in cases where a maximum frequency can be reached before a maximum control voltage is reached.
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