FREQUENCY SYNTHESIZER CIRCUIT

摘要

A frequency synthesizer circuit for a car radar system is disclosed, the circuit comprising: a phase locked loop for providing a frequency chirp at a range of tuning voltages, said phase locked loop comprising: a phase detector and a voltage controlled oscillator, wherein said phase locked loop has an open loop gain dependent on the tuning voltage and a gain of the voltage controlled oscillator; a first varactor unit for altering the gain of the voltage controlled oscillator over a first subset range of tuning voltages; and a second varactor unit for altering the gain of the voltage controlled oscillator over a second subset range of tuning voltages, wherein the second subset range of tuning voltages is higher than the first subset range of tuning voltages; such that variations in the open loop gain over the first and second subset range of tuning voltages of the range of tuning voltages are compensated for by the varactor units.

主权项

1. A frequency synthesiser circuit for a radar system, the circuit comprising:
a phase locked loop for providing a frequency chirp at a range of tuning voltages, said phase locked loop comprising: a phase detector; and a voltage controlled oscillator and wherein said phase locked loop has an open loop gain dependent on the tuning voltage and a gain of the voltage controlled oscillator;a first varactor unit for altering the gain of the voltage controlled oscillator over a first subset range of tuning voltages; anda second varactor unit for altering the gain of the voltage controlled oscillator over a second subset range of tuning voltages, wherein the second subset range of tuning voltages is higher than the first subset range of tuning voltages;such that variations in the open loop gain over the first and second subset range of voltages of the range of tuning voltages are compensated for by the varactor units.