| Summary: | 碩士 === 國立高雄師範大學 === 電子工程學系 === 103 === In this thesis, several radio-frequency (RF) circuits with transformers for the applications in Worldwide Interoperability for Microwave Access (WiMAX) and Wi-Fi are presented. Designed circuits are divided into two parts. The first part includes two mixers circuits using transformers to transform a single-ended signal into two differential signals. One mixer uses a transformer to transform a single-ended RF input into two differential signals and has a wide operation frequency bandwidth. The other mixer uses two transformers to transform a single-ended RF input and a single-end LO input into two differential signals, respectively. In the second part, a transformer is used to switch operation frequency band of dual-band low-noise amplifier (LNA). At first, one circuit using two discrete inductors to implement a dual-band LNA is presented. Then, the other circuit using two concentric switching inductors to implement a dual-band LNA is presented. The structure of the concentric switching inductors is a center-tapped self-coupling transformer. Finally, circuit performances of the two low-noise amplifiers are listed and compared.
In the mixer I, a mixer uses a transformer to transfer a single-end RF input signal into two differential signals and operates over a wide frequency bandwidth. The transformer together with extra inductors and capacitors implements a broad-bandwidth impedance matching at the input port and generate two differential input signals into the mixer. In the circuit, the input impedance matching is improved and the conversion gain is enhanced as compared to the chip presented previously by our laboratory. The circuit operates at the frequency band around 2.3 GHz. The conversion gain is 10.05 dB. The power consumption is 2.88 mW.
In the mixer II, a mixer uses two center-tapped transformers to transfer a single-end RF input into two differential signals and a single-end LO input into two differential signals, respectively. One transformer together with extra inductors and capacitors implements a broad-bandwidth impedance matching at the RF input port and generate two differential input signals into the mixer. At the LO port, the other transformer is also used to generate two differential LO signals into the mixer. The circuit operates at the frequency band around 2.3 GHz. The conversion gain is 10.81 dB. The power consumption is 3.52 mW.
In the LNA I, a dual-band LNA using two discrete inductors to implement a switching-inductor structure is presented. A p-type MOSFET in parallel with one inductor in the switching-inductor structure is used to switch the equivalent inductance of switching-inductor structure and hence the LNA can operate at one of two operation frequency bands. The circuit operates at the frequency band around 2.4 GHz or 5.8 GHz. The gains are 10.97 dB and 7.85 dB, respectively. The power consumption is 11.39 mW and 11.46 mW.
In the LNA II, a dual-band LNA using a concentric tapped self-coupling transformer, which is used to replace the two discrete inductors in the LNA I, is presented. The circuit operates at the frequency band around 2.4 GHz or 5.8 GHz. The gains are 14.03 dB and 8.23 dB, respectively. The power consumption is 10.59 mW and 10.56 mW, respectively.
In this thesis, the Advance Design System(ADS) is used to simulate and analyze the circuit performance. The circuit is based on the TSMC 0.18 μm CMOS process and the related device models. The chips is taped out and fabricated by applying to CIC.
|
|---|
