In this paper, we present a comprehensive stochastic model describing the measurement uncertainty, output signal, and limits of detection of affinity-based biosensors. The biochemical events within the biosensor platform are modeled by a Markov stochastic process, describing both the probabilistic mass transfer and the interactions of analytes with the capturing probes. To generalize this model and incorporate the detection process, we add noisy signal transduction and amplification stages to the Markov model. Using this approach, we are able to evaluate not only the output signal and the statistics of its fluctuation but also the noise contributions of each stage within the biosensor platform. Furthermore, we apply our formulations to define the signal-to-noise ratio, noise figure, and detection dynamic range of affinity-based biosensors. Motivated by the platforms encountered in practice, we construct the noise model of a number of widely used systems. The results of this study show that our formulations predict the behavioral characteristics of affinity-based biosensors which indicate the validity of the model.

Abstract-This paper reports a SAW-less direct-conversion receiver which utilizes a mixed-signal feedforward path to regenerate and adaptively cancel IM3 products, thus accomplishing system-level linearization. The receiver system performance is dominated by a custom integrated RF front end implemented in 130-nm CMOS and achieves an uncorrected out-of-band IIP3 of 7.1 dBm under the worst-case UMTS FDD Region 1 blocking specifications. Under IM3 equalization, the receiver achieves an effective IIP3 of +5.3 dBm and meets the UMTS BER sensitivity requirement with 3.7 dB of margin.

We propose a class of electrical circuits for extremely wideband ͑EWB͒ signal shaping. A one-dimensional, nonlinear, nonuniform transmission line is proposed for narrow pulse generation. A two-dimensional transmission lattice is proposed for EWB signal combining. Model equations for the circuits are derived. Theoretical and numerical solutions of the model equations are presented, showing that the circuits can be used for the desired application. The procedure by which the circuits are designed exemplifies a modern, mathematical design methodology for EWB circuits.

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A 2.4-GHz, 2.2-W, 2-V fully integrated circular geometry power amplifier with 50 hz input and output matching is fabricated using 2.5V, 0.35 pm CMOS transistors. It can also produce 450mW using a 1V supply. Harmonic suppression is 64dB or better. An on-chip circulargeometry active-transformer is used to combine several push-pull low-voltage amplifiers efficiently to produce a larger output power while maintaining a 50R match.This new on-chip power combining and impedance matching method uses virtual ac grounds and magnetic couplings extensively to eliminate the need for any offchip component such as wirebonds. It also desensitizes the operation of the amplifier to the inductance of bonding wires and makes the design more reproducible. This new topology makes possible a fully-integrated 2.2W, 2.4GHz, low voltage CMOS power amplifier for the first time.