Reference Circuit 4154

MAX2170/MAX2171 DAB/T-DMB Reference Design



Figure 1

Figure 1. The MAX2170/MAX2171 tuner plus demodulator reference design.

Figure 2
Figure 2. System Block Diagram 

Click here for an overview of the wireless components used in a typical radio transceiver.
Click here for an overview of the wireless components used in a typical radio transceiver.

Figure 1
Figure 1. The MAX2170/MAX2171 tuner plus demodulator reference design.
Figure 2
Figure 2. System Block Diagram

Lab Measurements

Figure 3
Figure 3. The VHF sensitivity measures better than -100.9dBm for DAB and better than -101.3dBm for T-DMB.
Figure 4
Figure 4. The L-Band sensitivity measures better than -100.6dBm for DAB and better than -100.7dBm for T-DMB.

Figure 5
Figure 5. The Adjacent Channel Selectivity (ACS) is better than 46dBc at the N±1 adjacents for VHF, and improves by almost 2dB for L-band. With these ACS measurements, the desired signal is at -70dBm and 206.352MHz for VHF and 1471.792MHz for L-band. The channel spacing is 1.712MHz.

 

Additional Measurements

The maximum input level is 10dBm for DAB and T-DMB in both VHF and L-band. This input level is limited by the absolute maximum rating of the MAX2170/MAX2171 devices.

DAB
Parameter Conditions Measured Units
Maximum Input VHF: 174.928, 206.352, 239.200MHz 10, 10, 10 dBm
L-Band: 1452.960, 1471.792, 1490.624MHz 10, 10, 10
Far-Off Selectivity, VHF
(Desired: -70dBm, 206.352MHz)
N+5MHz FM Adj 66.7 dBc
N-5MHz FM Adj 66.6
Far-Off Selectivity, L-Band
(Desired: -70dBm, 1471.792MHz)
N+5MHz FM Adj 67.0 dBc
N-5MHz FM Adj 66.9

T-DMB
Parameter Conditions Measured Units
Maximum Input VHF: 174.928, 206.352, 239.200MHz 10, 10, 10 dBm
L-Band: 1452.960, 1471.792, 1490.624MHz 10, 10, 10
Far-Off Selectivity, VHF
(Desired: -70dBm, 206.352MHz)
N+5MHz FM Adj 66.2 dBc
N-5MHz FM Adj 66.9
Far-Off Selectivity, L-Band
(Desired: -70dBm, 1471.792MHz)
N+5MHz FM Adj 67.0 dBc
N-5MHz FM Adj 66.9


DAB/T-DMB Frequency Plan

Figure 6
Figure 6. The DAB/T-DMB RF signal is typically broadcast in the VHF-III band and L-band. The channel spacing is typically 1.712MHz with 1.536MHz signal bandwidth.

Detailed Description

The MAX2170/MAX2171 low-IF tuner is designed for Digital Audio Broadcast (DAB) and Terrestrial Digital Multimedia Broadcast (T-DMB) applications, covering an input frequency range of 168MHz to 240MHz (VHF-III) and 1452MHz to 1492MHz (L-band). The MAX2170/MAX2171 achieve a high level of component integration, thus allowing low-power, tuner-on-board designs. The low-IF architecture eliminates the need for an IF-SAW filter, while providing a balanced 2.048MHz center frequency baseband output to the demodulator. The MAX2170 provides a buffered reference clock at the crystal frequency, while the MAX2171 outputs a reference at 1/3rd of the crystal frequency. A sigma-delta fractional-N synthesizer is incorporated to optimize both close-in and wideband phase-noise performances for OFDM applications where sensitivity to both 1kHz phase noise and wideband phase noise related to strong adjacents can be a problem.

 
Status:
Package:
Temperature:

MAX2170
Direct-Conversion to Low-IF Tuners for Digital Audio Broadcast

  • +2.7V to +3.5V Supply Voltage Range
  • Low-IF Output Eliminates IF-SAW Filter
  • Integrated Low-IF Bandpass Filter

MAX2171
Direct-Conversion to Low-IF Tuners for Digital Audio Broadcast

  • +2.7V to +3.5V Supply Voltage Range
  • Low-IF Output Eliminates IF-SAW Filter
  • Integrated Low-IF Bandpass Filter