A conventional wireless radio frequency (RF) receiver frontend topology comprises a low noise amplifier (LNA) arranged to amplifier signals received by an antenna, an active mixer (e.g. a Gilbert-type mixer) arranged to down-convert the amplified signals to a baseband frequency. Baseband filtering and variable gain amplification is then performed. Such a conventional RF receiver topology achieves good noise performance, but may eventually suffer from a poor compression point depending on the input signal level power.
Radar receivers, such as used within automotive advanced driver assistance systems, require both good noise and good compression point performance, and an acceptable trade-off using conventional receiver topologies is difficult to reach. To achieve good performance for both noise and compression point, radar receivers often use a different topology receiver frontend topology in which an unamplified signal received by the antenna is provided directly to the active mixer. By removing the LNA a better trade-off between noise and compression point can be achieved. However, the achievable receiver noise performance is limited, due mainly to the noise contribution of the active mixer because the mixer noise is not masked by any gain stage preceding it.
USPTO Backgrounds
USPTO Backgrounds