A digital isolator comprising a set of bipolar transistors and an inductor capacitor (LC) oscillator coupled to the set of bipolar transistors in series, wherein the LC oscillator is configured to be turned on and off based on the current applied to the set of bipolar transistors or the LC oscillator and generate a set of differential signals based on the current flowing through the set of bipolar transistors and mimicking the operational characteristics of an optocoupler.

An LC oscillator architecture in which an LC tank is driven by a negative resistance element (amplifier) including first and second Vbe/Vgs multipliers cross-coupled to the LC tank. Each Vbe/Vgs multiplier circuitry including a transistor with a control terminal as a negative input, a reference terminal as a positive input, and an output terminal, a shunt resistance connected between the control terminal and the reference terminal, a series resistance connected between the control terminal and the output terminal for one of the same transistor or the other transistor, and a shorting capacitance connected between the control terminal of the transistor, and the output terminal of the transistor of the other Vbe/Vgs multiplier. An example application is an LC VCO, such as for a PLL, CDR, or retimer.

An IQ signal source (100) includes: a Q-VCO (3) having a first VCO (1) and a second VCO (2), the IQ signal source (100) outputting an I signal and a Q signal by electrically coupling the first VCO (1) and the second VCO (2) with each other; a first PLL (10) for comparing a frequency of the I signal or the Q signal with a frequency of a reference signal input from the outside of the IQ signal source (100) and outputting a voltage depending on a result of the comparison; and a second PLL (9) for detecting an IQ phase difference and outputting a voltage depending on the IQ phase difference. The IQ phase difference converges to 90 degrees in dependence on the output voltage of the first PLL (10) and the output voltage of the second PLL (9).

An IQ signal source (100) includes: a Q-VCO (3) having a first VCO (1) and a second VCO (2), the IQ signal source (100) outputting an I signal and a Q signal by electrically coupling the first VCO (1) and the second VCO (2) with each other; a first PLL (10) for comparing a frequency of the I signal or the Q signal with a frequency of a reference signal input from the outside of the IQ signal source (100) and outputting a voltage depending on a result of the comparison; and a second PLL (9) for detecting an IQ phase difference and outputting a voltage depending on the IQ phase difference. The IQ phase difference converges to 90 degrees in dependence on the output voltage of the first PLL (10) and the output voltage of the second PLL (9).

A local oscillator of the present invention includes: a frequency generator for outputting first and second sinusoidal signals having the same frequency but mutually different phases; a phase detector for outputting either a positive or a negative voltage depending on whether a phase difference between the first and second sinusoidal signals output from the frequency generator is greater than a reference phase difference; and a comparator for outputting a comparison result between a voltage output from the phase detector and a reference voltage, or a comparison result between the voltage output from the phase detector and a voltage obtained by inverting the polarity of the voltage, in which the frequency generator controls the phase of the first sinusoidal signal so that the phase difference approaches the reference phase difference by using the comparison result output from the comparator, enabling generating IQ signals having higher phase accuracy than conventional local oscillators.

The present application relates to a differential Colpitts voltage-controlled oscillator (VCO) circuit, which comprises a pair of transistors with control terminals biased by a common biasing voltage and a pair of couplers arranged to cross-couple corrector/drain of the transistors and the base/gate of the differential transistors. The pair of couplers have a coupling factor k.sub.c, which used to enhance the transconductance of the transistor pair, therefore can be used for power consumption reduction and phase noise minimalization.

The disclosure relates to technology for power supply for a voltage controller oscillator (VCO). A peak detector circuit determines the amplitude of the output for the VCO, which is compared to a reference value in an automatic gain control loop. An input voltage for the VCO is determined based on a difference between the reference value and the output of the peak detector circuit. The peak detector circuit can be implemented using parasitic bipolar devices in an integrated circuit formed in a CMOS process.

A digital isolator comprising a set of bipolar transistors and an inductor capacitor (LC) oscillator coupled to the set of bipolar transistors in series, wherein the LC oscillator is configured to be turned on and off based on the current applied to the set of bipolar transistors or the LC oscillator and generate a set of differential signals based on the current flowing through the set of bipolar transistors and mimicking the operational characteristics of an optocoupler.

The present application relates to a differential Colpitts voltage-controlled oscillator (VCO) circuit, which comprises a pair of transistors with control terminals biased by a common biasing voltage and a pair of couplers arranged to cross-couple corrector/drain of the transistors and the base/gate of the differential transistors. The pair of couplers have a coupling factor k.sub.c, which used to enhance the transconductance of the transistor pair, therefore can be used for power consumption reduction and phase noise minimalization.

A voltage controlled oscillator includes a variable capacitance circuit having a plurality of variable capacitance elements, each having a capacitance that is a function of a tuning voltage, two or more oscillator core circuits, each operable over a specified frequency band, and inductive elements connected between the variable capacitance circuit and the oscillator core circuits.