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 oscillator includes a resonator, sustaining circuit and detector circuit. The sustaining circuit receives a sense signal indicative of mechanically resonant motion of the resonator generates an amplified output signal in response. The detector circuit asserts, at a predetermined phase of the amplified output signal, one or more control signals that enable an offset-reducing operation with respect to the sustaining amplifier circuit.

In examples, a voltage-controlled oscillator (VCO) comprises an inductor; a first pair of transistors having first terminals coupled to a voltage source, second terminals coupled to opposing ends of the inductor, and control terminals coupled to opposing ends of the inductor; and a second pair of transistors having first terminals coupled to ground, second terminals coupled to opposing ends of the inductor, and control terminals coupled to opposing ends of the inductor. The VCO also comprises a first transistor coupled to at least one capacitor, the combination of the first transistor and the at least one capacitor coupled to the inductor in parallel. The VCO further comprises second, third, and fourth transistors coupled to a control terminal of the first transistor, the second transistor coupled to the voltage source, the fourth transistor coupled to ground, and the third transistor configured to receive a ramped voltage.

A method and circuit for linearizing a frequency response of an oscillator controlled by a plurality of capacitor banks are disclosed. In the disclosed method, for each capacitor bank of at least two capacitor banks of the oscillator, a respective sensitivity characteristic of the capacitor bank is determined. Further, a set of reference output frequency control words (FCWs) for an associated set of frequencies of the oscillator are determined. When an input FCW is received and an output FCW is responsively provided based on (i) an interpolation between two reference output FCWs of the set of reference output FCWs and (ii) the respective sensitivity characteristics of the at least two capacitor banks of the oscillator. The output FCW is then applied to the at least two capacitor banks of the oscillator.

A biasing circuit for biasing a switching transistor, wherein the switching transistor is used for switching a respective capacitor cell into/out of a capacitor array, wherein the capacitor array comprises one or more such capacitor cells, and wherein the capacitor array is coupled in parallel with a primary inductor to form an inductive/capacitive tank. The biasing circuit comprises a secondary inductor which is inductively coupled to the primary inductor, the secondary inductor configured to provide a bias signal for biasing the switching transistor.

A switched capacitor arrangement for tuning a differential circuit is disclosed. The switched capacitor arrangement comprises a first node, a second node and a third node. The switched capacitor arrangement further comprises a first capacitor coupled between the first node and the second node, a second capacitor coupled between the second node and the third node, and a first switch branch comprising a first switch coupled between the second node and a signal ground node. The first switch has an on state and an off state. The first node and third node are configured to be connected to respective differential nodes of the differential circuit. The switched capacitor arrangement is configured to tune the differential circuit by controlling the state of the first switch.

According to one embodiment, there is provided a semiconductor device including a first switch, a first capacitive element, a second capacitive element, a first rectifying circuit, a second rectifying circuit, a third rectifying circuit, and a fourth rectifying circuit. The first switch is electrically inserted between a first node and a second node. The first capacitive element is electrically inserted between a first signal node and the first node. The second capacitive element is electrically inserted between a second signal node and the second node. The first rectifying circuit is electrically connected to the first node with a first polarity. The second rectifying circuit is electrically connected to the first node with a second polarity opposite to the first polarity. The third rectifying circuit is electrically connected to the second node with the first polarity. The fourth rectifying circuit is electrically connected to the second node with the second polarity.

In examples, a voltage-controlled oscillator (VCO) comprises an inductor; a first pair of transistors having first terminals coupled to a voltage source, second terminals coupled to opposing ends of the inductor, and control terminals coupled to opposing ends of the inductor; and a second pair of transistors having first terminals coupled to ground, second terminals coupled to opposing ends of the inductor, and control terminals coupled to opposing ends of the inductor. The VCO also comprises a first transistor coupled to at least one capacitor, the combination of the first transistor and the at least one capacitor coupled to the inductor in parallel. The VCO further comprises second, third, and fourth transistors coupled to a control terminal of the first transistor, the second transistor coupled to the voltage source, the fourth transistor coupled to ground, and the third transistor configured to receive a ramped voltage.

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.