Recently, there has been a growing interest in implantable wireless biotelemetry for diagnosis as the advancement of microelectronic technologies. A lot of biosensors including temperature sensor, moisture sensor, and gas sensor and so forth have been proposed such that the front end of the implantable system can get the wanted signals. The characteristics of these sensors are to transfer the measured bio-signal into the electrical signal which is required by the succeeding circuits. According to the parameters imbedded in the signal, different systems may be designed to process different bio-signals. Since there is a limit processing ability for the system as far as implantation is concerned, general methods are then converting the signal into the digital form by the analog-to-digital converter (ADC) and then followed by a digital transceiver to transmit the digital signal to the outside world. Because of the signal quality required by the data processing, a good transceiver is therefore necessary. This is the reason why the transceiver is usually the bottleneck of the whole system. Thus, if the transmitted signal can be received correctly from the outside world, many analyses can be done easily. This thesis is then focused on the realization of the transmitter and the receiver interfaces. In the chapter 2 of this thesis, we will present an analog solution for wireless biotelemetry. We use a simple integrated FM (frequency modulation) transmitter for a specific bio-signal such as electrocardiograms (ECG) for heart rate variability (HRV) test. The size of this transmitter is comparable to that of a rice grain and thereby is suitable for implantation purpose. The advantages of this solution are simple and cheap because a radio only can be used as the receiver. However, the signals that can be processed by this system are limited, so another solution is needed. In the chapter 3 of this thesis, we introduce a digital microsystem solution for signal processing. The modulation mechanism of digital transceiver is by using amplitude-shift keying (ASK). The advantages of ASK are easy implantation and small size, etc.. In that chapter, we will design two ASK receivers by different demodulating concepts. The other circuit described in that chapter is the power-on reset (POR). This circuit is to generate a trigger signal to wake up the rest circuits of the system. In the final chapter, typical receiver architectures for cell phone communication are discussed. An important block in the receiver structure is the voltage-controlled oscillator (VCO). Many design issues such as varactors, inductors, and phase noise of the VCO are discussed in that chapter. Typical models for phase noise are based on linear-time invariant (LTI) and linear-time varying (LTV) analyses. Another explanation for phase noise is a non-linear closed-form model and can been seen in this thesis. Next, a quadrature VCO for image-reject receiver is designed. Usually, the measurement of phase relationship for high frequency is complex and inaccuracy. In this thesis, we introduced a calibration method for phase measurement. Finally, a switched-capacitor VCO designed from 2.4 GHz to 3.0 GHz is presented for wireless local area network (WLAN) 802.11a, b, and g multi-band application. A comparison between different works can be seen in the thesis.