Current-Driven Phase Shifter for FMCW Radar Noise Reduction
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Solution Overview
Problem
Existing phase shifter circuits in radar systems face challenges in reducing total noise and power consumption, particularly in integrated transceivers, where the phase shifter often contributes significantly to noise and power usage.
Innovation Solution
A current-driven phase shifter topology with switchable bias sources and switching circuitry is implemented, allowing for low output noise and efficient power management by powering up/down the phase shifter during interchirp periods in FMCW radar frames, utilizing a balun with inductors and a current-summing digital-to-analogue converter to minimize noise and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a phase shifter circuit is used in a radar transmitter, then beam forming capability and radar resolution are improved, but total noise in the output increases and power consumption increases
Solution Approach 1:
The patent implements dynamic power management by enabling the phase shifter circuit to switch between active and inactive states. During interchirp periods in FMCW radar frames, the phase shifter is powered down to reduce noise and power consumption. This dynamic operation maintains beam forming capability during active chirps while minimizing harmful noise contributions during inactive periods.
Solution Approach 2:
The phase shifter is powered up and down periodically synchronized with the radar's FMCW frame structure. The control circuitry coordinates power state transitions with chirp transmission timing, ensuring the phase shifter is active only when required for beam forming during chirp transmission and inactive during interchirp periods, thereby reducing average noise and power consumption.
2Adaptability or versatility
If a phase shifter circuit is used in a radar transmitter, then beam forming capability is improved, but power consumption increases
Solution Approach 1:
The phase shifter circuit implements dynamic power state transitions between active and inactive modes. The control circuitry monitors radar operational state and adjusts phase shifter power consumption accordingly, maintaining beam forming adaptability during active chirps while minimizing power usage during interchirp periods.
Solution Approach 2:
The system temporarily discards phase shifter operation during interchirp periods when beam forming is not required, and recovers full functionality during active chirps. This periodic activation strategy maintains necessary adaptability while significantly reducing average power consumption of the phase shifter circuit.
Data Source
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AI summary
A fast current driven phase shifter topology presenting very low output noise and circuitry for powering up/down the phase shifter during an interchirp period of a radar receiver frequency-modulated continuous-wave (FMCW) frame, thereby reducing total radar device power consumption. The phase shifter circuit has an active state and an inactive state, the phase shifter circuit comprising:a digital-to-analogue converter (222) configured to receive a control signal (Ictrl, Qctrl) indicative of a desired phase shift and to provide an analogue current (ip, in) in accordance with the desired phase shift;a mixer stage (242) configured to mix an oscillator signal (VCO) with the analogue current to provide a phase shifted signal; and control circuitry (217, 252) configured to provide the oscillator signal to the mixer stage in accordance with the state of the phase shifter to activate or deactivate the mixer stage.