Recent increasing demands for IoT device, wearable device and biomedical implants have been calling for more low power, energy efficient and highly integrated devices from electronic industry. Implementing transmitter and energy-harvesting circuits on a same chip is a good way to provide battery-less systems for data transmission in wireless sensor networks. Prior wireless powered devices work used sub-gigahertz microwaves and require very large antenna for energy harvesting, which prevents their application in biomedical implants and single-chip integration. Our work on battery-less transmitter integrated on-chip antenna for 8 to 10 GHz wireless energy harvesting. This approach reduced antenna size and provided stable 10uW energy source for duty-cycled operating transmitter. The transmitter used On-Off Key (OOK) modulation. Oscillator, a class-E power amplifier and a dipole on-chip antenna are the main components of the transmitter. The transmitter operates at 1.46GHz and consumes 25mW power. The on-chip antenna is matched to the transmitter at 1.46GHz and could radiate up to -20dBm power into the air. By modulating from an external signal source, the data rate can be as high as 50M Bit/sec. The transmitter is able to harvest power from a radiating antenna 30cm away from the chip with a size of 7.4mm2 and transmit data back. Thus it is suitable for biomedical implant and wearable devices. On the other hand, our work introduced a frequency-agile receiver that detect and switch to the most power efficient channel quickly. The receiver consists of a band-switching low noise amplifier (LNA), an all-digital-phase-locked-loop (ADPLL), a power detector and a successive approximation analog to digital converter. The receiver worked at 4.3 to 5.7GHz and provide quick band-switching on the LNA and ADPLL. It provides quick and accurate channel selection in quickly changing environments.