A CMOS wideband, highly linear low noise amplifier for digital TV applications

Abstract

Recently, the Analog TV is quickly replaced to the Digital TV in all around world since the Digital TV support better resolution and sound quality. In addition, the Digital TV supports internet-based services such as banking, shopping, and interactive broadcasting on TV. However, the Digital TV has many issues due to using same frequency range with the Analog TV. First, the intermodulation between undesired channels can affect the desired channel due to low and wideband, 48-860 MHz. Amplitude difference is another issue due to saturation of the Digital TV tuner. Both are critically related with the channel selectivity of the Digital TV tuner and can be expressed as specifications of harmonic mixing, linearity and dynamic range. In order to solve above issues, the off-chip RF tracking filter is adopted in the early Digital TV tuner. However, it increases price of tuner and needs a tuning for deciding the frequency range of the off-chip RF tracking filter. Therefore, the research of the single chip tuner is grown with increasing market of the Digital TV tuner for cheap price. This dissertation proposed several techniques in the low noise amplifier (LNA), a first block in the Digital TV Tuner. First, the LNA for the Digital TV adopts the resistor load instead of inductor load due to its low and wide frequency range of 40-860 MHz. However, input matching in the wideband LNA depends on the transconductance of the input matching transistor different with the narrow band LNA. Therefore, the gain and noise figure (NF) have trade-off relationship in the wideband LNA. Normally, NF characteristic of the wideband LNA is high. In order to solve high NF issue, the noise cancelling technique, cancel the noise source of the matching transistors, was proposed and many papers of the wideband LNA adopted this novel technique. This dissertation also adopts this noise cancelling technique. Second, a limitation of the noise cancelling technique is analyzed in the view of linearity ...