A vector signal generator with direct RF signal synthesis is disclosed. The vector signal generator comprises an RF signal synthesizer, a switch, and a memory. The RF signal synthesizer is configured for converting baseband IQ signals into a modulated digital RF signal. The RF signal synthesizer is connected to an I input, a Q input, a clock input, a control input, and an output, where the clock input is a clock input of the vector signal generator, the control input is a control input of the vector signal generator, and the output is an RF signal output of the vector signal generator. The switch is configured for selecting a source of IQ signals and is connected to an external I input, an external Q input, a stored signal I input, a stored signal Q input, the control input, an I output, and a Q output. The external I input and external Q input are external IQ inputs to the vector signal generator and the I output and the Q output are connected to the I input and the Q input of the RF signal synthesizer. The memory is configured for storing IQ signals samples, said memory being connected to the control input and having a stored I output, connected to the stored signal I input, and a stored Q output connected to the stored signal Q input.