Theory, engineering design, fabrication, and experimental test of the first completely monolithic grating amplifier realized in silicon are described. Experimental results are presented for frequencies between 0.1 and 2.0 GHz at 300 K for the device, referred to as the solid state space harmonic amplifier structure. Electronic gain is about 1.5 dB/mm with a cold circuit loss of 4.6 dB/mm for the 200‐&mgr;m‐long interaction region device.