||Since the combination of antigens with the corresponding antibody will change the|
resonant frequency of certain MEMS sensors, this kind of technology is often utilized for
a rapid screen test, e.g., allergy testing, Carcinoembryonic Antigen (CEA) and Alphafetoprotein
(AFP) cancer marker detection using flexural plate wave (FPW) devices. The
thesis consists of two important designs for the mentioned frequency-shifting sensoring
systems, i.e., a 10-bit process-calibrated current-steering DAC and high bandwidth and
high coversion gain power detector.
A frequency-shift readout system needs to drive sensors such that DACs are indispensable.
The 10-bit process-calibrated current-steering DAC in this thesis utilizes a process
sensor to detect process corners and generate corresponding digital codes, which are
coupled to a current calibration circuit to compensate the output voltage. An auxiliary delay
circuit is employed in the current source to cut off the un-activated calibration current.
The maximum DNL and INL are measured to be 0.18 LSB and 0.32 LSB, respectively.
The other design of this thesis presents a high bandwidth and high coversion gain
power detector for the frequency-shift readout system. This design is basically composed
of two common source amplifiers, followed by a peak detector or a valley detector to
detect the presence of the resonant frequency. Besides, the range of frequency detection
is 0.1 GHz ∼ 16 GHz. The coversion gain is as high as 264 mV/dB such that the
power detector will enhance the accuracy and widen the operating frequency range of the
frequency-shift readout systems.