Apparatus and methods for biasing low noise amplifiers are provided herein. In certain configurations, a low noise amplifier (LNA) includes an input, an output, a transconductance device, a cascode device, a bias current source, and a feedback bias circuit. The transconductance device generates an amplified signal by amplifying an input signal received at the input, and provides the amplified signal to the output via the cascode device. The bias current source generates a bias current that flows through the cascode device and the transconductance device. The feedback bias circuit provides feedback from the LNA's output to the LNA's input to control an input bias voltage of the transconductance device.