A system, method and apparatus for tuning an internal oscillator to a desired frequency F1 is shown and uses an RC delay element that comprises a resistor, a capacitor and a comparator. The method includes receiving a clock signal from an oscillator to be tuned, triggering charging of the RC delay element, and N clock cycles after triggering the charging, the method determines whether the charge on the precision RC delay element is higher than or lower than a reference voltage. Correction to the clock frequency is based on the results.

A system, method and apparatus for tuning an internal oscillator to a desired frequency F1 is shown and uses an RC delay element that comprises a resistor, a capacitor and a comparator. The method includes receiving a clock signal from an oscillator to be tuned, triggering charging of the RC delay element, and N clock cycles after triggering the charging, the method determines whether the charge on the precision RC delay element is higher than or lower than a reference voltage. Correction to the clock frequency is based on the results.

An oscillator circuit arrangement comprises a gain stage and a feedback loop that includes a crystal device. A clock signal monitor circuit is connected to an output of the gain stage and detects a frequency shift in the clock signal or a loss of oscillation. The current through the gain stage is controlled in response to a control signal generated by the clock signal monitor circuit.

An all-digital voltage monitor (ADVM) generates a multi-bit output code that changes in proportion to a voltage being monitored, by leveraging the voltage impact on a gate delay. ADVM utilizes a simple delay chain, which receives a clock-cycle-long pulse every clock cycle, such that the monitored supply voltage is sampled for one full cycle every cycle. The outputs of all delay cells of the delay chain collectively represents a current voltage state as a digital thermometer code. In AVDM, a voltage droop event thus results in a decrease in the output code from a nominal value, while an overshoot results in an increase in the output code.

An atomic oscillator includes: an atom cell in which alkali metal atoms are accommodated; a light-emitting element that emits light beams for exciting the alkali metal atoms toward the atom cell; a shield that includes a first member, a second member, and a high thermal resistance portion and accommodates the atom cell, the first member and the second member being members having a magnetic shielding property, and the high thermal resistance portion being provided between the first member and the second member and having a thermal resistance higher than thermal resistances of the first member and the second member; a temperature control element that controls a temperature of the first member; a heater that is thermally coupled to the second member; and a light-receiving element that receives light beams passing through the atom cell.

An atomic oscillator includes: an atom cell in which alkali metal atoms are accommodated; a light-emitting element that emits light beams for exciting the alkali metal atoms toward the atom cell; a shield that includes a first member, a second member, and a high thermal resistance portion and accommodates the atom cell, the first member and the second member being members having a magnetic shielding property, and the high thermal resistance portion being provided between the first member and the second member and having a thermal resistance higher than thermal resistances of the first member and the second member; a temperature control element that controls a temperature of the first member; a heater that is thermally coupled to the second member; and a light-receiving element that receives light beams passing through the atom cell.

Provided is a variable resistance circuit in which the resistance value of the variable resistance circuit can be accurately adjusted, by reducing the error in the change amount of the resistance value of the variable resistance circuit due to the on-resistances of switch circuits even if the switch circuits that each bypass a resistor included in a ladder resistor circuit are switched between an OFF state and an ON state. This variable resistance circuit includes: a ladder resistor circuit including a plurality of resistors; a first switch circuit connected in series to one end of one resistor of the plurality of resistors; and a second switch circuit connected in parallel to a series circuit of the one resistor and the first switch circuit. When one of the first and second switch circuits is turned on, the other of the first and second switch circuits is turned off.

Provided is a variable resistance circuit in which the resistance value of the variable resistance circuit can be accurately adjusted, by reducing the error in the change amount of the resistance value of the variable resistance circuit due to the on-resistances of switch circuits even if the switch circuits that each bypass a resistor included in a ladder resistor circuit are switched between an OFF state and an ON state. This variable resistance circuit includes: a ladder resistor circuit including a plurality of resistors; a first switch circuit connected in series to one end of one resistor of the plurality of resistors; and a second switch circuit connected in parallel to a series circuit of the one resistor and the first switch circuit. When one of the first and second switch circuits is turned on, the other of the first and second switch circuits is turned off.

A system, method and apparatus for tuning an internal oscillator to a desired frequency F1 is shown and uses an RC delay element that comprises a resistor, a capacitor and a comparator. The method includes receiving a clock signal from an oscillator to be tuned, triggering charging of the RC delay element, and N clock cycles after triggering the charging, the method determines whether the charge on the precision RC delay element is higher than or lower than a reference voltage. Correction to the clock frequency is based on the results.

A system, method and apparatus for tuning an internal oscillator to a desired frequency F1 is shown and uses an RC delay element that comprises a resistor, a capacitor and a comparator. The method includes receiving a clock signal from an oscillator to be tuned, triggering charging of the RC delay element, and N clock cycles after triggering the charging, the method determines whether the charge on the precision RC delay element is higher than or lower than a reference voltage. Correction to the clock frequency is based on the results.