A 2 GHz balanced harmonic mixer for direct-conversion receivers

To reduce DC offset caused by LO signal self-mixing in a direct-conversion receiver, a balanced harmonic mixer was proposed and fabricated by using a silicon bipolar technology. The measured self-mixing DC offset was equivalent to -92 dBm at the mixer input and is of the same order as equivalent input noise. This makes it possible to use a simple offset cancellation technique to overcome the self-mixing problem.