Oscillator circuit, corresponding radar sensor, vehicle and method of operation

A circuit, comprising:

• a tunable resonance circuit comprising:
• an inductance directly electrically connected in series between first and second nodes;
• a variable capacitance directly electrically connected between the first and second nodes;
• and
• a set of switched capacitances coupled between the first and second nodes, the set of switched capacitances including a plurality of capacitance units, each capacitance unit comprising a first capacitance for that capacitance unit directly electrically connected between the first node and a switch and a second capacitance for that capacitance unit directly electrically connected between the switch and the second node;
• control circuitry configured to receive an input control signal and connected to control the switches of the set of switched capacitances, wherein the control circuitry comprises a digital-to-analog converter configured to receive the input control signal as input and generate a control word for the switches of the set of switched capacitances as output;
• and
• a biasing circuit directly electrically connected to the tunable resonance circuit at the first and second nodes.

A method of operating a tunable resonant circuit, comprising:

• receiving an input control signal at a tap node between first and second inductances coupled in series between first and second nodes;
• receiving a control word at a set of switched capacitances coupled between the first and second nodes, the set of switched capacitances including a plurality of capacitance units, each capacitance unit comprising a first capacitance for that capacitance unit coupled between the first node and a switch and a second capacitance for that capacitance unit coupled between the switch and the second node;
• receiving the input control signal at inputs of a flash analog-to-digital converter (ADC) and operating the flash ADC to:
• quantize an operating frequency range for an output signal produced between the first and second nodes as M·Δf, where M is an integer value ranging from 0 to N−1, where N is a number of intervals into which a frequency range for the output signal is divided, and where Δf is a resulting frequency step produced by the quantization;
• and
• generate a value of M based upon the input control signal and outputting the control word to the switches of the plurality of capacitance units to close ones of those switches associated with the control word to thereby coarsely tune a frequency of the output signal;
• and
• performing a fine continuous tuning of the frequency of the output signal by adjusting an adjustable capacitance coupled between the first and second nodes.

A circuit, comprising:

• a tunable resonance circuit comprising:
• first and second inductances coupled in series between first and second nodes, with a tap node between the first and second inductances configured to receive an input control signal;
• first and second variable capacitances coupled between the first and second nodes;
• and
• a set of switched capacitances coupled between the first and second nodes, the set of switched capacitances including a plurality of capacitance units, each capacitance unit comprising a first capacitance for that capacitance unit coupled between the first node and a switch and a second capacitance for the capacitance unit coupled between the switch and the second node;
• and
• a flash analog-to-digital converter (ADC) configured to receive the input control signal and perform a coarse quantized tuning of a frequency of an output signal produced between the first and second nodes by:
• quantizing an operating frequency range for the output signal produced between the first and second nodes as M·Δf, where M is an integer value ranging from 0 to N−1, where N is a number of intervals into which a frequency range for the output signal is divided, and where Δf is a resulting frequency step produced by the quantization;
• and
• generating a value of M based upon the input control signal and outputting a control word to the switches of the plurality of capacitance units to close ones of those switches associated with the control word to thereby coarsely tune a frequency of the output signal.