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.

A radio frequency (RF) wave generator includes a nonlinear transmission line and a pulse generator. The nonlinear transmission line has in order an input section, a magnetic section, and an output section. The magnetic section includes a nonlinear magnetic material. The pulse generator is configured to provide an input pulse to the input section which is converted to an RF wave by the nonlinear transmission line. A waveform of the input pulse is such that the generated RF wave is parametrically amplified.

Apparatus and methods for rotary traveling wave oscillators (RTWOs) are provided herein. In certain configurations, an RTWO includes a differential transmission line connected in a ring and a plurality of segments distributed around the ring. The segments include metal stubs extending from the RTWO's differential transmission line. The metal stubs aid in providing access to additional layout resources for tuning capacitors and other circuitry of the RTWO's segments, while permitting the length of RTWO's ring to be relative short. Thus, the metal stubs do not inhibit the RTWO from operating with relatively high oscillation frequency, while providing connectivity to tuning capacitors that tune the RTWO's oscillation frequency over a wide tuning range and/or provide fine frequency step size.

Apparatus and methods for frequency tuning of rotary traveling wave oscillators (RTWOs) are provided herein. In certain configurations, distributed quantized tuning is used to tune a frequency of the RTWO. The RTWO includes a plurality of segments distributed around the RTWO's ring, and the segments include tuning capacitors and other circuitry. The distributed quantized frequency tuning is used to control the tuning capacitors in the RTWO's segments using separately controllable code values, thereby enhancing the RTWO's frequency step size or resolution. Moreover, in configurations including multiple RTWO rings that are locked to one another to reduce phase noise, the distributed quantized frequency tuning can be used to separately set the tuning capacitors across multiple RTWO rings that are coupled to one another.

There is disclosed herein clock generation circuitry, in particular rotary travelling wave oscillator circuitry. Such circuitry comprises a pair of signal lines connected together to form a closed loop and arranged such that they define at least one transition section where both said lines in a first portion of the pair cross from one lateral side of both said lines in a second portion of the pair to the other lateral side of both said lines in the second portion of the pair.