Automotive forward looking sensor

摘要

A forward looking sensor (FLS) has a transmit antenna (52) and a receive antenna (56). The receive antenna (56) is coupled through a low noise amplifier (122) and a single sideband generator (126) to a down-converting mixer (146) which supplies an intermediate frequency signal to a further down-converting mixer (158). The further downconverted signal is supplied to an analog-to-digital converter stage (166) of a digital signal processor (60). The transmit antenna (52) receives a signal for transmission from a voltage controlled oscillator (VCO) (70) in a transmitter circuit (50). A control signal (72) for the VCO (70) is generated in response to the output of a mixer (84), which is supplied with a portion of the transmitted signal from a coupler (82), and a local oscillator signal from a dielectric resonator oscillator (86). The mixer output (92) is linearized by a linearization circuit (80). The linearization circuit (80) has a phase or frequency detector (96) which produces the control signal by comparing a fixed reference frequency signal (98) with a frequency divided signal (106) derived from the mixer output (92). The frequency division is controlled by a counter (100).