Mixer circuits with direct-current bias are disclosed. An example embodiment of such a mixer includes a first differential transistor pair and a second differential transistor pair. The example mixer also includes first and second local oscillator signal terminals and first and second mixed signal terminals. The first and second local oscillator signal terminals are coupled with the first and second differential transistor pairs. The first mixed signal terminal is coupled with the first differential pair and the second mixed signal terminal is coupled with the second differential pair. The mixer further includes first and second baseband signal terminals, where each baseband signal terminal is coupled with the first differential pair and the second differential pair. The mixer still further includes a first current source and a second current source. The first current source is coupled with the first differential pair and the first mixed signal terminal, and provides a first direct-current bias to the first differential pair. The second current source is coupled with the second differential pair and the second mixed signal terminal, and provides a second direct-current bias to the second differential pair.