Analog frequency response measurement in mixed-signal systems

We present an efficient approach for on-chip frequency response measurement, including phase and gain, of analog circuitry in mixed-signal systems. The approach uses direct digital synthesizer (DDS) to supply test sine waves with different frequencies and phases. The output response is analyzed using a multiplier and accumulator. The resultant phase delay measurement is used to correct other measurements such as gain and linearity for more accurate testing and characterization of the analog circuit under test. The approach was implemented in Verilog, synthesized in a field programmable gate array (FPGA), and used for frequency response measurements of an actual device under test