Dynamic IQ mismatch correction in FMCW radar

Patent metadata

Field	Value
Publication number	US-10145937-B2
Application number	US-201615088566-A
Country	US
Kind code	B2
Filing date	Apr 1, 2016
Priority date	Apr 1, 2016
Publication date	Dec 4, 2018
Grant date	Dec 4, 2018

Abstract

A FMCW radar receiver includes a LO providing a chirped LO signal, an in-phase (I) channel for outputting I-data and a quadrature (Q) channel for outputting Q-data. A dynamic correction parameter generator generates IQ phase correction values (P[n]s) and IQ gain correction values (G[n]s) based on a frequency slope rate of the chirped LO signal for generating during intervals of chirps including a first sequence of P[n]s and G[n]s during a first chirp and a second sequence of P[n]s and G[n]s during a second chirp. An IQ mismatch (IQMM) correction circuit has a first IQMM input coupled to receive the I-data and a second IQMM input receiving the Q-data, and the P[n]s and G[n]s. During the first chirp the IQMM correction circuit provides first Q′-data and first I′-data and during the second chirp the IQMM correction circuit provides at least second Q′-data and second I′-data.

First claim

The invention claimed is:

1. A method of IQ mismatch correction for Frequency Modulation Continuous Wave (FMCW) radar, comprising:
providing an IQ FMCW receiver including an in-phase (I) channel comprising a first mixer coupled to receive and mix a chirped local oscillator signal (chirped LO signal) and a received scattered chirped radar signal (chirped radar signal) and a first analog-to-digital (A/D) converter for outputting in-phase (I)-data, and a quadrature (Q) channel including a phase shifter for phase shifting said chirped LO signal to provide a phase shifted chirped LO signal, a second mixer coupled to receive and mix said chirped radar signal and said phase shifted chirped LO signal and a second A/D converter for outputting Q phase (Q)-data;
dynamically generating IQ phase correction parameter values (P[n]s) and IQ gain correction parameter values (G[n]s) based on a slope rate of a frequency of said chirped LO signal including generating different values during a plurality of intervals for each chirp of said chirped LO signal;
coupling said P[n]s and said G[n]s to an IQ mismatch (IQMM) correction circuit having a first IQMM input coupled to receive said I-data from said I channel and a second IQMM input for receiving said Q-data from said Q-channel,
wherein said IQMM correction circuit provides corrected Q (Q′) data and corrected I (I′) data.

2. The method of claim 1 , wherein said dynamically generating further comprises generating a first sequence of said P[n]s and a first sequence of said G[n]s during a first chirp and a second sequence of said P[n]s and a second sequence of said G[n]s different from said first sequence of said P[n]s and G[n]s during a second chirp, and
wherein during a duration of said first chirp said IQMM correction circuit provides first Q′ data and first I′ data and during a duration of said second chirp said IQMM correction circuit provides second Q′ data and second I′ data.

3. The method of claim 1 , wherein said dynamically generating comprises utilizing delta (Δ) G IQ correction values (ΔG[n]s) and ΔP IQ correction values (ΔP[n]s) stored in a look-up table (LUT), and wherein based on said slope rate and a starting frequency of said chirped LO signal during each said chirp a LUT index generator causes said LUT to output a selected one of said ΔG[n]s to a gain correction parameter accumulator to generate each one of said G[n]s and one of said ΔP[n]s to a phase correction parameter accumulator to generate each one of said P[n]s.

4. The method of claim 3 , wherein said LUT index generator provides selection of a new frequency threshold from a frequency threshold look-up table (LUT) based on a current LUT index provided by said LUT index generator.

5. The method of claim 1 , wherein said dynamically generating comprises gated accumulating comprising populating a look-up table (LUT) with an incremental change in a value of said G[n]s and said P[n]s for an absolute jump in frequency (ΔF) of said chirped LO signal for each of said plurality of intervals across a frequency band for said chirped LO signal,
wherein an accumulation gating signal generator receives said slope rate for monitoring a change in said frequency of said chirped LO signal based on an accumulation of said slope rate and is coupled to trigger gated accumulations in said gain correction parameter accumulator to output each one of said G[n]s and said phase correction parameter accumulator to output each one of said P[n]s by performing gated accumulations every said ΔF, and
wherein said slope rate is further coupled to a LUT index generator that is coupled to provide a slope-rate-based LUT index selection signal to said LUT.

6. The method of claim 5 , wherein said LUT index generator includes selection of a new frequency threshold from a frequency threshold look-up table (LUT) based on a current LUT index provided by said LUT index generator.

7. The method of claim 1 , wherein said IQ FMCW receiver comprises a CMOS receiver on a silicon substrate, and said method further comprises processing at least said I′ data and said Q′ data using a signal processing algorithm to determine at least one radar parameter.

8. A synchronous Frequency Modulation Continuous Wave (FMCW) radar receiver, comprising:
a substrate that said receiver is formed on;
a local oscillator (LO) controlled for providing a chirped LO signal;
an in-phase (I) channel comprising a first mixer coupled to receive and mix said chirped LO signal and a received scattered chirped radar signal (chirped radar signal) and a first analog-to-digital (A/D) converter for outputting in-phase (I)-data, and a quadrature (Q) channel including a phase shifter for phase shifting said chirped LO signal to provide a phase shifted chirped LO signal, a second mixer coupled to receive and mix said chirped radar signal and said phase shifted chirped LO signal and a second A/D converter for outputting Q phase (Q)-data;
a dynamic correction parameter generator for dynamically generating IQ phase correction parameter values (P[n]s) and IQ gain correction parameter values (G[n]s) based on a slope rate of a frequency of said chirped LO signal provided by a timing engine, the dynamic correction parameter generator generating different values during a plurality of intervals for each chirp of said chirped LO signal, and
an IQ mismatch (IQMM) correction circuit including at least a third mixer having a first IQMM input coupled to receive said I-data from said I channel and a second IQMM input for receiving said Q-data from said Q-channel, said IQMM correction circuit coupled to receive said P[n]s and said G[n]s;
wherein said IQMM correction circuit provides corrected Q (Q′)-data and corrected I (I′)-data.

9. The FMCW radar receiver of claim 8 , wherein said dynamic correction parameter generator generates a first sequence of said P[n]s and a first sequence of said G[n]s during a first chirp and a second sequence of said P[n]s and a second sequence of said G[n]s different from said first sequence of said P[n]s and G[n]s during a second chirp,
wherein during a duration of said first chirp said IQMM correction circuit provides first Q′-data and first I′-data and during a duration of said second chirp said IQMM correction circuit provides second Q′-data and second I′-data.

10. The FMCW radar receiver of claim 8 , wherein said dynamic correction parameter generator utilizes delta (Δ) G IQ correction values (ΔG[n]s) and ΔP IQ correction values (ΔP[n]s) stored in a look-up table (LUT), and wherein based on said slope rate and a starting frequency of said chirped LO signal during each said chirp a LUT index generator causes said LUT to output a selected one of said ΔG[n]s to a gain correction parameter accumulator to generate each one of said G[n]s and one of said ΔP[n]s to a phase correction parameter accumulator to generate each one of said P[n]s.

11. The FMCW radar receiver of claim 10 , wherein said LUT index generator selects of a new frequency threshold from a frequency threshold look-up table (LUT) based on a current LUT index provided by said LUT index generator.

12. The FMCW radar receiver of claim 8 , wherein said dynamic correction parameter generator performs gated accumulating at least in part by populating a look-up table (LUT) with an incremental change in a value of said G[n]s and said P[n]s for an absolute jump in frequency (ΔF) of said chirped LO signal for each of said plurality of intervals across a frequency band for said chirped LO signal, and
wherein an accumulation gating signal generator receives said slope rate for monitoring a change in said frequency of said chirped LO signal based on an accumulation of said slope rate and is coup

Assignees

• Texas Instruments Inc

Inventors

• Gupta Pankaj
• Murali Sriram
• Ramasubramanian Karthik

Classifications

• G01S7/352 Primary

  Receivers · CPC title

• H03D3/009

  Compensating quadrature phase or amplitude imbalances · CPC title

• G01S13/931

  of land vehicles · CPC title

• G01S13/343

  using sawtooth modulation · CPC title

• G01S7/4021

  of receivers · CPC title