A device comprising: a voltage reference supply, configured to provide a reference voltage that varies in response to temperature according to a predefined relationship; a temperature sensor providing a temperature signal indicating a temperature; a first controller configured to receive the temperature signal and to output a control signal; an LC-DCO receiving the reference voltage and providing an output signal with a frequency from an LC circuit, the LC-DCO comprising a switched capacitor bank configured to provide temperature compensation by varying an effective capacitance in the LC circuit in response to the control signal.

A crystal driver integrated circuit configurable for daisy chaining including an amplifier core, an input pin and an output pin, and a controller that operates the amplifier core in any one of multiple operating modes. The operating modes include an oscillator mode for driving an external crystal coupled between the input and output pins to generate an oscillation signal at a target frequency, and an amplifier mode that amplifies an external oscillating signal provided to the input pin to provide an amplified oscillation signal on the output pin. The amplifier core includes a controllable current source that provides a core bias current to an amplifier having a level that is adjusted depending upon the operating mode and desired amplitude. The operating modes may include a bypass mode in which the amplifier core is disabled. The amplifier may be implemented as either an PMOS amplifier or an NMOS amplifier.

In some embodiments, the present disclosure relates to a frequency generator having a resistor network and a capacitor network. The capacitor network has a plurality of capacitors connected in parallel with one another. A comparator is configured to output an oscillating voltage signal. An input of the comparator is connected to the output of the resistor network and the output of the capacitor network. A frequency testing circuit is configured to calculate a frequency of the oscillating voltage signal and determine whether the frequency is within a range of an expected frequency. The frequency testing circuit may also be configured to selectively connect a first plate of the plurality of capacitors to a non-varying voltage or to the input of the capacitor network to adjust a frequency of the oscillating voltage signal.

A semiconductor device including: a resistor element connected to one and another end of a crystal oscillator; an adjustable current type inverter element having an input connected to one end of the resistor element and an output connected to another end of the resistor element; a first capacitor element connected to the input of the inverter element and to ground; a second capacitor element having one end connected to ground; a first switching element that switches a connection state of the one end of the first capacitor element and another end of the second capacitor element; a third capacitor element connected to the output of the inverter element and to ground; a fourth capacitor element having one end connected to ground; and a second switching element that switches a connection state of the one end of the third capacitor element and another end of the fourth capacitor element.

A method and a circuit for exciting a crystal oscillation circuit are disclosed herein. The crystal oscillation circuit comprising: charging, with a charging circuit, a voltage-controlled oscillator; providing, with the voltage-controlled oscillator, an exciting signal; blocking, with a direct current blocking capacitor, direct current from the voltage-controlled oscillator to the crystal oscillation circuit; and exciting, with the exciting signal, the crystal oscillation circuit. The circuit for exciting a crystal oscillation circuit, comprising: a charging circuit; a voltage-controlled oscillator coupled to the charging circuit and configured to provide an exciting signal to the crystal oscillation circuit; and a direct current blocking capacitor connected between the voltage-controlled oscillator and the crystal oscillation circuit and configured to block direct current from the voltage-controlled oscillator.

An RC oscillator has a variable capacitor that sets the output frequency. The variable capacitor has m binary-weighted switched capacitor arrays, and each binary-weighted switched capacitor array has binary-weighted capacitors. p binary bits are decoded into an m-bit thermometer code that selects one of the m binary-weighted switched capacitor arrays to use n binary bits to switch its binary-weighted capacitors. Other binary-weighted switched capacitor arrays have all their capacitors switched on, or all their capacitors switched off by the thermometer code. The smallest or unit capacitance of each binary-weighted switched capacitor array is adjusted to compensate for the non-linear reciprocal relationship of frequency being proportional to 1/RC. The unit capacitance is increased for each successive binary-weighted switched capacitor array to reset to the ideal linear relationship of the (p,n)-bit code to frequency.

An oscillator, including a resonance circuit, a cross coupled current source circuit, and a positive feedback circuit coupled between the current source circuit and the resonance circuit, where the resonance circuit is configured to generate a differential oscillation signal having a first oscillation frequency, the positive feedback circuit is configured to receive the differential oscillation signal, and amplify a gain of the differential oscillation signal to obtain a differential output oscillation signal, and the current source circuit is configured to provide an adjustable bias current for the resonance circuit and the positive feedback circuit. Since, the current source circuit provides the adjustable bias current for the positive feedback circuit and the resonance circuit, and forms a transconductance boosted (Gm-boosted) structure with the positive feedback circuit, the positive feedback circuit can amplify the gain of the received differential oscillation signal to obtain the differential output oscillation signal.

An RC oscillator has a variable capacitor that sets the output frequency. The variable capacitor has m binary-weighted switched capacitor arrays, and each binary-weighted switched capacitor array has binary-weighted capacitors. p binary bits are decoded into an m-bit thermometer code that selects one of the m binary-weighted switched capacitor arrays to use n binary bits to switch its binary-weighted capacitors. Other binary-weighted switched capacitor arrays have all their capacitors switched on, or all their capacitors switched off by the thermometer code. The smallest or unit capacitance of each binary-weighted switched capacitor array is adjusted to compensate for the non-linear reciprocal relationship of frequency being proportional to 1/RC. The unit capacitance is increased for each successive binary-weighted switched capacitor array to reset to the ideal linear relationship of the (p,n)-bit code to frequency.

An LC tank circuit, such as an LC tank circuit of a step-tuned voltage controlled oscillator, includes an inductor and one or more capacitors. The inductor can be dog-bone shaped with a body, an extension and a chamfered joint to improve current distribution. The body and the extension can extend along different directions. The body can be narrower than the extension, and the extension can be sufficiently wide to interface with a plurality of switched capacitor circuits coupled to different parts of the extension.

An LC tank circuit, such as an LC tank circuit of a step-tuned voltage controlled oscillator, includes a plurality of switched capacitor banks and one or more inductors. A first switched capacitor bank switch in response to a range of control signals used to control the VCO output across a range of frequencies. A second switched capacitor bank can switch in response to a subset of the range of control signals used to control the VCO output across a subset of the range of frequencies. The control scheme for the first and second switched capacitor banks can improves the linearity of changes in the frequency of the output signal of the VCO.