Abstract: The ingrated, single-conversion terrestrial tuner f ATSC and NTSC is A/74 compliant. The MAX3540 converts a input signal in the 54MHz to 860MHz band to a 44MHz balanced-IF output.
Figure 1. The evaluaon board for the MAX3540 single-conversion terrestrial tuner for ATSC/NTSC.
Figure 2. Tuner system block diag.
The ATSC system performance of the MAX3540 with an ATSC demodulator is shown below.
Figure 3. Desired-to-undesired ratio (D/U) measurements meet the A/74 specification with at least 2dB of margin. These measurements are for a weak desired signal at -68dBm with an ATSC undesired signal.
| Parameter |
Measured |
A/74 Specification |
Unit |
| Sensitivity |
-85 typical |
-83 |
dBm |
| um Signal |
-2 typical |
-8 |
dBm |
Table 1. The margin to A/74 is typically 2dB for sensitivity and 6dB for maximum signal. |
|
Figure 4. The ATSC/NTSC RF signal is broast in the VHF Low, VHF High, and UHF bands, as shown above. The channel sping is 6MHz.
The MAX3540 is a complete single-conversion television tuner designed for use in /digital terrestrial applications and digital set-top boxes. This television tuner draws only 760mW of power from a +3.3V supply voltage.The MAX3540 is designed to convert NTSC or ATSC signals in the 54MHz to 860MHz band to a 44MHz intermediate frequency (IF).The MAX3540 includes a variable-gain low-noise amplifier, multiband tracking filte, a harmonic-rejection mixer, a low-noise IF amplifier, an IF power detector, and a variable-gain IF amplifier. The MAX3540 also includes fully-monolithic VCOs and tank circuits, as well as, a complete frequency synthesizer. This highly integrated design allows for low-power tuner-on-board applications without the cost and power-dissipation issues of dual-conversion tuner solutions. The MAX3540 is specified for operation in the 0°C to +85°C temperature range, and is available in a leless 48-n flip-chip (fcLGA) package.
MAX3540完备的一次变频电视调谐器专为/数字陆地接收机和数字机顶盒设计。该电视调谐器采用+3.3V，功耗仅为760mW。MAX3540能够将54MHz至860MHz带宽内的NTSC或ATSC信号转换成44MHz中频(IF)信号。MAX3540包括可变增益低噪声(LNA)、多频带跟踪、谐波抑制混频器、低噪声IF放大器、IF功率检测器以及可变增益IF放大器。MAX3540还集成了单片VCO、谐振电路以及完整的频率合成器。这款高集成度适用于低功耗板上调谐器应用，不存在二次变频调谐器方案中的成本及功耗等问题。MAX3540工作在0°C至+85°C温度范围，采用48引脚、无铅倒装(fcLGA)封装。