This thesis consists of two topics. A frequency-shift readout circuit is integrated for the rapid IgE measurement biomedical system in the first half. Secondly, we present a ROM-less DDFS (direct digital frequency synthesis) using a non-equal division parabolic polynomial interpolation method, which is used as the frequency generator in the measurement system. The first topic investigates the IgE concentration measurement system and realizes the readout circuit using TSMC 1P6M 0.18 £gm CMOS technology. We integrate the flexural plate wave (FPW) sensor chips and an ASIC comprising control block, digital to analog convertor (DAC), OTA-C oscillators, amplifiers, peak detectors, registers, and a subtractor. By taking advantages of the characteristics that the central frequencies of the loaded FPW sensors will be shifted, sine waves with various frequencies are generated and swept through one pair of FPW sensors. The frequency difference of these sensors is then readout to get concentration by look-up table. The second topic investigates the division method of a quarter sine wave to improve the spurious free dynamic range (SFDR) and realizes a ROM-less DDFS which is used as the frequency generator in the mentioned IgE measurement system. The proposed non-equal division parabolic polynomial interpolation method will generate a complete sine wave by a quarter of a sine digital signal owing to the symmetry. We combine the quasi-linear interpolation and an offset adjustment to derive the quarter sine wave digital signals. The proposed method not only reduces the absolute error between ideal sine wave and generated sine wave, it also improves SFDR.