Abstract: A crystal oscillator circuit is configured to output an oscillation signal. A bias circuit responds to control signal to generate a bias current for application to the crystal oscillator circuit. A current generator generates a sense current from the control signal. The sense current is compared to a reference current by a comparator circuit. The comparator circuit generates a ready signal in response to the comparison. The ready signal is indicative of whether the oscillation signal output from the crystal oscillator circuit is ready for use by other circuitry. The reference current may be generated by a circuit which replicates the bias circuit.

Abstract: A power supply apparatus includes a power supply circuit and a power-on circuit. The power-on circuit detects a remotely transmitted control signal and causes a transition of the power supply circuit to a turned on state. The power-on circuit includes a transducer configured to provide a power-on signal in response to the remote control signal. The transducer triggers transition to the turned on state through a switch driven by the power-on signal output from the transducer and arranged to supply a power supply circuit enable signal. A DC blocking capacitor is connected between an output of the transducer and a control terminal of the switch.

Abstract: A crystal oscillator circuit is configured to output an oscillation signal. A bias circuit responds to control signal to generate a bias current for application to the crystal oscillator circuit. A current generator generates a sense current from the control signal. The sense current is compared to a reference current by a comparator circuit. The comparator circuit generates a ready signal in response to the comparison. The ready signal is indicative of whether the oscillation signal output from the crystal oscillator circuit is ready for use by other circuitry. The reference current may be generated by a circuit which replicates the bias circuit.