A variable-gain amplifier and a phased array system are provided. A variable-gain amplifier includes a cascode circuit comprising a first amplification transistor and a second amplification transistor array that are cascaded, the second amplification transistor array comprising a plurality of second amplification transistors connected in parallel and configured to output an adjustable current to an output matching network, the first amplification transistor is a common-source transistor, the plurality of second amplification transistors are common-gate transistors, or the cascode circuit is a common-emitter common-base circuit, the first amplification transistor is a common-emitter amplification circuit, and the second amplification transistor array is a common-base amplification circuit. The variable-gain amplifier further including a variable capacitor circuit coupled to the second amplification transistor array and coupled to the output matching network at first nodes.