On-wafer wireless testing and mismatch monitoring using RF transmitters with integrated antennas

This paper presents two fully integrated transmitters with embedded antennas to demonstrate on-wafer wireless testing for the first time. The proposed transmitters are intended to not only replace the I/O pins during manufacturing testing but also to serve as process monitoring circuits. The first RF transmitter, operating at 5.5 GHz, utilizes a current-reuse LC oscillator to minimize complexity and power consumption. Implemented in a 0.13-mum CMOS technology, the inductor in the LC tank doubles as a loop antenna. With 10 cm of separation between the on-chip loop antenna and the off-chip discrete antenna, the transmitter supports OOK modulation of up to 10 Mbps at 0.15 nJ/bit and FSK modulation of up to 2 Mbps at 1.5 nJ/bit. The second transmitter design employs a 1.2-GHz Hartley image-reject transmitter in an InGaP/GaAs HBT process to demonstrate both wireless data link and process control monitoring. Both dipole and loop antennas are integrated to study their radiation efficiency as their dimensions are much less than the wavelength of the 1.2-GHz carrier. The loop antenna provides about 7 dB better transmission gain. The image rejection ratio is measured wirelessly from a number of samples to monitor the die-to-die variations in the I/Q mismatch. The wireless measurements are consistent with direct contact probing.