A Group Delay Compensation Power Amplifier with Auto Power Level Control for 24GHz FMCW Automobile Radar Application

A group-delay compensation power amplifier (PA) is proposed in this paper. Equalizer based on the all-pass filter is used to reduce the chirp signal linearity distortion caused by the nonlinear group delay of the PA. The group delay variation of the whole PA is less than ±5ps. An auto power-level control loop is adopted to stabilize the output power against the temperature and process variation. The control loop is based on the power detector and charge pump. The different output power level can be set using the loop directly to satisfy the needs of different detection distance. The power gain of the PA is 21.5 dB and the maximum output power is 14.5 dBm. The 2f0 impedance is controlled to improve the power added efficiency (PAE). The maximum PAE reaches 33.5%. The size of the whole chip is 0.8×0.9 mm².