A packaged VCTCXO may include a crystal oscillator configured to output a signal of a particular frequency and a temperature sensor configured to measure an internal temperature of the crystal oscillator. In addition, the packaged VCTCXO may include a microcontroller configured to generate an internal control voltage signal based at least in part on the temperature and an external control voltage received by the packaged VCTCXO. Moreover, the packaged VCTCXO may include a combiner configured to combine an internal control voltage and the external control voltage to generate a control voltage. Further, the control voltage may be supplied to the crystal oscillator to cause the crystal oscillator to generate the signal of the particular frequency.

A packaged VCTCXO may include a crystal oscillator configured to output a signal of a particular frequency and a temperature sensor configured to measure an internal temperature of the crystal oscillator. In addition, the packaged VCTCXO may include a microcontroller configured to generate an internal control voltage signal based at least in part on the temperature and an external control voltage received by the packaged VCTCXO. Moreover, the packaged VCTCXO may include a combiner configured to combine an internal control voltage and the external control voltage to generate a control voltage. Further, the control voltage may be supplied to the crystal oscillator to cause the crystal oscillator to generate the signal of the particular frequency.

A crystal oscillator is coupled to a digital automatic gain control (AGC) having oscillation detection and amplitude control loops. The oscillation detection loop may increase the transconductance (gm) of the oscillator transistor until oscillation is detected therefrom. Then the amplitude control loop detects the amplitudes of oscillations from the crystal oscillator, compares these amplitudes to high and low voltage references and generates digital signals to find a critical transconductance (gm) for an oscillator amplifier and control this gm to maintain a constant oscillation waveform amplitude therefrom. An up/down counter defines the servo control loop bandwidth/update-rate according to an update clock rate thereto. Loop stability is achieved when the control loop bandwidth is less than the start-up time required for the oscillation envelope of the crystal oscillator to grow for oscillation. An oscillator failure detector may also be provided.

Disclosed is a temperature-compensated crystal oscillator based on analog circuit; a closed-loop compensation architecture determines the temperature compensation of a crystal oscillator. The power splitter divides the VCXO's current output signal with frequency f=f.sub.0+Δf into two signals, one signal to output of the TCXO and the other signal is sent to an analog frequency-voltage conversion circuit. According to the frequency of the VCXO's current output signal, the analog frequency-voltage conversion circuit produces a voltage signal V(T), which corresponds to current ambient temperature. The difference between V(T) and a reference voltage signal V.sub.ref is produced and amplified to obtain a compensation voltage signal ΔV through a voltage matching circuit. ΔV is smoothed by a filter, then sent to the voltage control terminal of the VCXO to make the VCXO generate a stable signal with desired frequency f.sub.0, to compensate the frequency of the VCXO's output signal when the ambient temperature is changed.

Disclosed is a temperature-compensated crystal oscillator based on analog circuit; a closed-loop compensation architecture determines the temperature compensation of a crystal oscillator. The power splitter divides the VCXO's current output signal with frequency f=f.sub.0+Δf into two signals, one signal to output of the TCXO and the other signal is sent to an analog frequency-voltage conversion circuit. According to the frequency of the VCXO's current output signal, the analog frequency-voltage conversion circuit produces a voltage signal V(T), which corresponds to current ambient temperature. The difference between V(T) and a reference voltage signal V.sub.ref is produced and amplified to obtain a compensation voltage signal ΔV through a voltage matching circuit. ΔV is smoothed by a filter, then sent to the voltage control terminal of the VCXO to make the VCXO generate a stable signal with desired frequency f.sub.0, to compensate the frequency of the VCXO's output signal when the ambient temperature is changed.

An amplification interface includes first and second differential input terminals, first and second differential output terminals providing first and second output voltages defining a differential output signal, and first and second analog integrators coupled between the first and second differential input terminals and the first and second differential output terminals, the first and second analog integrators being resettable by a reset signal. A control circuit generates the reset signal such that the first and second analog integrators are periodically reset during a reset interval and activated during a measurement interval, receives a control signal indicative of offsets in the measurement sensor current and the reference sensor current, and generates a drive signal as a function of the control signal. First and second current generators coupled first and second compensation circuits to the first and second differential input terminals as a function of a drive signal.

An amplification interface includes first and second differential input terminals, first and second differential output terminals providing first and second output voltages defining a differential output signal, and first and second analog integrators coupled between the first and second differential input terminals and the first and second differential output terminals, the first and second analog integrators being resettable by a reset signal. A control circuit generates the reset signal such that the first and second analog integrators are periodically reset during a reset interval and activated during a measurement interval, receives a control signal indicative of offsets in the measurement sensor current and the reference sensor current, and generates a drive signal as a function of the control signal. First and second current generators coupled first and second compensation circuits to the first and second differential input terminals as a function of a drive signal.

A microwave generator includes a power supply, an output circuit, a feedback oscillator, a pulse controller, a signal combination circuit and a semiconductor amplifier. The power supply converts input voltage and input current into output voltage and output current. The output circuit generates a microwave signal to an output terminal of the microwave generator and a feedback signal according to the microwave signal. The feedback oscillator generates an oscillation signal according to the feedback signal. According to a reference signal, the pulse controller generates a pulse signal. According to the oscillation signal and pulse signal, the signal combination circuit generates a control signal. The semiconductor amplifier generates and adjusts an amplified signal according to the control signal. The output circuit generates the microwave signal according to the amplified signal. The output current is adjusted according to the amplified signal. Consequently, the input current and the input voltage are in phase.

An oscillator circuit includes: a first temperature detector, detecting an internal temperature of the oscillator circuit; a current generator, generating a heater current so that the internal temperature matches a target temperature; a first and second heater, heating the resonator and the integrated circuit, respectively, based on the heater current; a second temperature detector, detecting a temperature of the integrated circuit; a first compensation voltage generation circuit, generating a first compensation voltage for compensating for a frequency variation due to a temperature change in the integrated circuit, based on a detection result of the second temperature detector; a second compensation voltage generation circuit, generating a second compensation voltage for compensating for a frequency variation due to a temperature change in the resonator, based on a detection result of the first temperature detector; and an oscillator, generating an oscillation signal based on the first and second compensation voltages.

An oscillator circuit includes: a first temperature detector, detecting an internal temperature of the oscillator circuit; a current generator, generating a heater current so that the internal temperature matches a target temperature; a first and second heater, heating the resonator and the integrated circuit, respectively, based on the heater current; a second temperature detector, detecting a temperature of the integrated circuit; a first compensation voltage generation circuit, generating a first compensation voltage for compensating for a frequency variation due to a temperature change in the integrated circuit, based on a detection result of the second temperature detector; a second compensation voltage generation circuit, generating a second compensation voltage for compensating for a frequency variation due to a temperature change in the resonator, based on a detection result of the first temperature detector; and an oscillator, generating an oscillation signal based on the first and second compensation voltages.