Abstract: The MAX3540 integrated, single-conversion terrestrial tuner IC for ATSC and NTSC is A/74 compliant. The MAX3540 converts a RF input signal in the 54MHz to 860MHz band to a 44MHz balanced-IF output.
Figure 1. The evaluation board for the MAX3540 single-conversion terrestrial tuner for ATSC/NTSC.
Figure 2. Tuner system block diagram.
Lab Measurements
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
Maximum 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 broadcast in the VHF Low, VHF High, and UHF bands, as shown above. The channel spacing is 6MHz.
Detailed Description
The MAX3540 is a complete single-conversion television tuner designed for use in analog/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 filters, 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 leadless 48-pin flip-chip (fcLGA) package.
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