Automatic control circuits for generators of electronic oscillations or pulses; starting, synchronization, or stabilization circuits for generators where the type of generator is irrelevant or unspecified.

Stabilisation of generator output against variations caused by environmental variations such as temperature, process variations when the generator is (partly) integrated on an electronic chip, aging of the components constituting the generator.

Documents disclosing compensation against temperature variations and against another physical parameter are classified in the subgroup H03L 1/02 in addition to H03L 1/00.

Said distributed capacitances and inductances could be also delay lines, microstrips, and the like.

All devices having a variable capacitance e.g. Junction capacitors, MOS-capacitors, and the like.

also ovens for maintaining temperature constant

Arrangements for automatic controlling the output level/amplitude of the generator. The output of the generator could be a voltage, current or power.

Arrangements for automatic controlling the output power level of the generator.

All documents for automatic controlling the frequency or phase of the output of the generator.

All means for converting the frequency to any of voltage, current or digital signal e.g. frequency-to-voltage converter, frequency-to-current converter, frequency-to-digital converter.

Distributed capacitances and inductances could be also delay lines, microstrips, and the like.

The reference signal is a frequency reference signal including constant frequency signal, data signal, and the like.

More than loop having each its own controlled oscillator and/or phase shifter.

the "loop" meaning a Phase-locked loop (PLL) or a Delay-locked loop (DLL).

Recovery circuit for recovering the reference signal from the input signal, e.g. data signal.

Controlled phase shifter in the loop e.g. delay element, phase selector, phase interpolator, and the like.

This subgroup does not include additional phase shifter outside the loop e.g. in the reference path or in the output path.

Delay-locked loops.

Controlled phase shifter which is digitally controlled e.g. by a register and/or an up-down counter.

Reference signal being additionally directly applied to the controlled oscillator in the loop.

Phase or frequency detector generating up-down pulses at separate terminals of the detector.

The up-down pulses being generated by the same phase or frequency detector.

Means for adjusting or tuning the value of the source or sink current.

the phase or frequency detector using a sampling device (H03L 7/087 takes precedence)

Phase or frequency detectors comprising sampling devices such as flip-flops, A/D converters, or the like.

Loop filtering, amplification, or any other manipulation of the signal provided by the phase/frequency detector which results in a control signal for the controlled oscillator of the loop.

Details of the lock detector.

Frequency to voltage converters converting the frequency of the reference signal and the frequency of the feedback signal to a voltage, current or digital signal. The voltage, current or digital signal is used by the comparator.

Digital oscillators which are analogly or digitally controlled.

Counter or frequency divider being part of the controlled digital oscillator.

Digital oscillators comprising an accumulator e.g. Direct Digital Synthesizers (DDS).

Means for speeding up the lock-in of the loop in general.

Low pass loop filter having a variable bandwidth for the purpose of assuring synchronisation or broadening the capture range of the PLL.

Arrangements and methods for assuring constant output frequency of the generator when the reference signal fails or is interrupted, or when the control signal of the controlled oscillator of the PLL or the controlled delay of the DLL fails or is interrupted.

Mixer in addition to the frequency divider or counter.

When the means for coarse tuning the controlled oscillator is not specific for frequency synthesizers, the document would be (additionally) classified in the subgroup H03L/10.

At least two different signals generated by the frequency divider or the counter or derived from frequency divider or counter output are used by the phase/frequency detector.

Also multi-modulus dividers.

Also Delta-Sigma modulators used for controlling the counter or frequency divider.

More than loop having each its own controlled oscillator and/or phase shifter.

e.g. injection-locked oscillators, oscillator arrays, mutually-coupled oscillators.

e.g. atomic clocks.