此論文內容在於建立一個可感測環境頻譜的頻譜感測系統，並透過0.18-μm CMOS製程來實現。該系統由低雜訊放大器、混頻器，低通濾波器，整流器，電壓比較器，數位控制單元和頻率合成器所組成。透過波峰檢測，頻譜感測範圍能從401.569 MHz到802.745 MHz，其中接收訊號的頻率訊息和訊號強度可以分別由10位元的數位頻率輸出和5位元的訊號強度指標所表示。 此系統的頻率解析度為392.2 kHz、感測時間小於0.164秒、動態範圍可達到48 dB、平均顯示雜訊位準可達到-134.9 dBm/Hz，感測靈敏度為-75 dBm。
接著，此論文考慮了所有寄生電容和電阻的情況下重新推導基於超級源極隨耦器之低通濾波器的轉移函數和穩定性公式。透過新推導的公式，濾波器的極點和零點頻率其理論值和模擬結果可以非常一致。也可以從新推導的公式中明確指示濾波器的穩定性和Q值，因此可以準確地預測基於超級源極隨耦器之低通濾波器的性能。此論文設計了兩個四階低通濾波器的範例，其製程是使用90-nm CMOS製程，兩者頻寬皆為1.3 GHz。在範例1中，相位邊限的理論值與模擬值之間的差異小於2度，各項頻率的理論值與模擬值之間差異小於8％。在範例2中，相位邊限的理論值與模擬值之間的差異小於4度，各項頻率的理論值與模擬值之間差異小於5％。

A spectrum sensing system is designed and implemented using 0.18-μm CMOS technology for cognitive radio applications. This system consists of a low noise amplifier (LNA), a mixer, a low-pass filter (LPF), a rectifier, a voltage comparator, a digital control unit (DCU) and a frequency synthesizer. Based on envelope detection, spectrum sensing is performed from 401.569 to 802.745 MHz, where the frequency information and signal strength of the received signal can be presented by the 10-bit digital frequency output and 5-bit signal strength index, respectively. The system achieves the sensing time of 0.164 sec, the dynamic range of 48 dB, the displayed average noise level (DANL) of -134.9 dBm/Hz, and sensing sensitivity of -75 dBm with the frequency resolution of 392.2 kHz.
Formulas of the transfer function and stability of the super-source-follower-based LPF are newly derived by considering all the parasitic capacitances and resistances. With the newly derived formula, the theoretical value and the simulation result of the pole and zero frequencies of the LPF can be very consistent. The stability and Q value of the filter can be indicated in the newly derived formula, so the performance of super-source-follower-based LPF can be predicted accurately. Two cases of the 4th-order LPF are designed in 90-nm CMOS technology and achieve 1.3 GHz of bandwidth. In case 1, the difference between the theoretical and simulated PM is < 2 degree and the frequency difference between the theoretical value and simulation results is < 6%. In case 2, the difference between the theoretical and simulated PM is < 4 degree and the frequency difference between the theoretical value and simulation results is < 4%.

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