Asahi Kasei Microdevices Corporation

North Carolina State University

Takeji Fujibayashi

Brian Allan Floyd

Seiji Takeuchi

A PLL circuit including a digitally controlled oscillator outputting, as an output signal, a signal having a frequency modulated according to a control signal, a detection unit detecting a difference in at least one of a ratio or a phase of a frequency between the output signal and a reference signal, a digital loop filter smoothing an output indicating the difference output from the detection unit and outputs, as the control signal, a resulting output to the digitally controlled oscillator, a control signal storage unit storing, as a previous control signal, a digital value based on the control signal output from the digital loop filter in a predetermined period immediately before end of a chirp operation period, and a control unit controlling the digital loop filter such that the control signal output from the digital loop filter immediately after start of the chirp operation period is the previous control signal.

PLL circuit

A phase adjusting circuit is provided, including a signal generation circuit receiving a frequency adjusting signal and generating a reference signal having a frequency corresponding to the frequency adjusting signal; a first path receiving the reference signal and providing a first signal; a second path receiving the reference signal and providing a second signal, and time for the reference signal passing through the second path is different from time for the reference passing through the first path; a phase shifter disposed on the first path or the second path and shifting a phase of the reference signal based on a phase adjusting signal; a phase difference detection circuit detecting a phase difference between the first and the second signals; and an adjusting signal generation circuit generating the frequency adjusting signal and the phase adjusting signal based on the phase difference so that the phase difference becomes a target value.

Phase adjusting circuit and phase adjusting method

The transmitter includes a phase shifter that shifts a phase of an input signal and outputs a shifted signal; a first control circuit changes a phase shift amount of the phase shifter; a phase difference signal output circuit outputs a phase difference signal between the shifted signal and the reference signal; an extreme value output circuit outputs a value of the phase difference signal when the phase difference signal becomes the extreme value; a target value output circuit outputs a target value based on an output from the extreme value output circuit; and a second control circuit controls the phase shift amount of the phase shifter such that a value of the phase difference signal coincides with the target value. The phase shifter outputs, as a transmission wave, the input signal the phase of which is shifted by the phase shift amount controlled by the second control circuit.

Transmitter, transmission method, phase adjustment device, and phase adjustment method

This invention describes circuits and methods which can allow multiple radar receiver chips to be adjusted to have very low phase offset between them. Multiple receiver chips are used in frequency-modulated carrier-wave (FMCW) radar systems for beamforming to enable angle-of-arrival measurements. FMCW radar systems are widely used in collision-avoidance and adaptive cruise control systems in vehicles, which today are operating in the 76-81 GHz frequency band. In a multi-receiver system, each receive element must have a well-controlled phase response which can be calibrated over process, voltage, and temperature. Without calibration, phase offsets can result in erroneous beamforming receiver measurements. The inventive circuit provides a technique to adjust the phase of multiple receivers across multiple chips using a single local oscillator reference and built-in-test circuitry which consist of phase shifters, a multi-frequency nonlinear phase detection circuit, and power coupling circuits.

Phase calibration circuit and method for multi-channel radar receiver

There is provided a circuit for adjusting phases of IQ local signals. As to a local signal A and a local signal B generated by a local signal generating unit for the purpose of generating IQ quadrature local signals, the local signal B in which the gain is adjusted is added to the output of the local signal A to obtain the local signal A, and the local signal A in which the gain is adjusted is subtracted from the output of the local signal B to obtain the local signal B. Even if the phase relationship between the local signal A and the local signal B deviates from 90 degrees, the phase difference between the local signal Aand the local signal Bcan be adjusted with ease by changing the adjustment amounts of variable amplifiers AMPand AMP

Growing community of inventors

Tokyo, Japan

Takeji Fujibayashi