在傳輸訊號選擇方面，使用了FSK調變解調，其相較於其它調變具有較的低複雜度與較高的抗干擾能力，因此特別適用於超低功耗傳輸系統。延遲電路設計方面，則使用了寬頻電流式放大器電路，實現了電流式的相位位移電路，達到800 μA的電流消耗下，此相位鍵移接收器具有20 Mb/s之資料傳輸速度，以達到超低功率消耗與縮短傳輸所需時間的目的。 An ultra-low power (ULP) frequency shift keying (FSK) receiver had be applied for wearable or implantable physiology sensors in recent years. Comparing to the other signal modulation, FSK provides better immunity against interference. Therefore, the ULP FSK receiver is suitable to provide stable link quality and extend life time of sensors. In this paper, we propose an ultra-low power, high data rate and variable data rate FSK receiver. The ULP FSK receiver was combined by a ULP Front-end and a ULP demodulator. Otherwise, we use current-mode phase shifter to improve bandwidth of the demodulator. High energy efficiency can be achieved by reducing the energy consumption per received bit of FSK receiver. Owing to variable data rate of the FSK demodulator, the power consumption of the FSK receiver can be trade-off for optimization under different operating conditions.
The ULP FSK receiver was implemented in 0.18 μm CMOS process. The simulated maximum data rate is 20 Mb/s under power consumption of 1.44 mW. Therefore, the minimum energy consumption of 72 pJ per received bit can be achieved under maximum data rate of 20 Mb/s.