Low Noise Amplifier and Programmable Gain Amplifier for DVB-T

This thesis is focused on a wideband low noise amplifier and a programmable gain amplifier for DVB-T fabricated with TSMC 0.18μm CMOS process. The wideband low noise amplifier is designed by the resistor feedback technique. It is divided into two stages. The first stage is designed by current-reuse topology to improve gain and to reduce power consumption. There is good input matching in the first step by choosing an appropriate resistor of the feedback resistors. The second stage is designed to increase the whole amplifier gain. It is also designed by the resistor feedback method to improve bandwidth performance. It uses a PMOS device which operates in linear region to provide a good output impedance matching. According to the measurement results, the amplifier gain is 21.5dB to 21.8dB. It simply varies 0.3dB in the bandwidth. S11 is smaller than -12.7dB. S22 is smaller than -12dB. NF is 3dB~4.7dB. And IIP3 is -5dBm~-5.6dBm in the bandwidth.

The operating frequency of the programmable gain amplifier is 50MHz to 860MHz. The structure of the amplifier is differential. And it is divided into two stages. The first stage is designed by current-reuse topology to improve gain and to reduce power consumption. It is also designed by the resistor feedback technique to improve bandwidth. By changing feedback resistors, it can change gain value. The topology of the output buffer is common drain. And it provides a good output impedance matching at the second stage. And using the current source of the second stage and the amplifier of the first stage achieves the thermal noise canceling result. Based on the measured results, the gain is -6dB to 14dB with 1dB gain step. S11 is smaller than -8dB. S22 is smaller than -8.5dB. NF is 6.5dB~8.5dB when the gain is 14dB. IIP3 is -8dBm when the gain is 14dB and IIP3 is 8dBm when the gain is -6dB.