基于MAX3580的DVB-T参考设计
图1. 基于MAX3580、满足NorDig和MBRAI标准的DVB-T调谐器参考设计。
图2. 系统框图
实验室测试结果
图3. 在VHF频段，测试数据显示本参考设计相对于NorDig 1.0.2标准具有2dB以上的裕量。
图4. 在UHF频段，测试数据显示本参考设计相对于NorDig 1.0.2标准具有3.5dB至5dB的裕量。
详情介绍
图1. 基于MAX3580、满足NorDig和MBRAI标准的DVB-T调谐器参考设计。
图2. 系统框图
实验室测试结果
图3. 在VHF频段，测试数据显示本参考设计相对于NorDig 1.0.2标准具有2dB以上的裕量。
图4. 在UHF频段，测试数据显示本参考设计相对于NorDig 1.0.2标准具有3.5dB至5dB的裕量。
NorDig指标比较
| Parameter | Conditions | Measured | NorDig | Units |
|---|---|---|---|---|
| Operating Frequency Range | VHF-III Band: 170MHz to 230MHz | – | ||
| UHF Band: 470MHz to 870MHz | – | |||
| Sensitivity, Gaussian Channel (VHF-III Band) |
QPSK, 8k, CR = 1/2, GI = 1/4 | -97.3 | -94.6 | dBm |
| 16QAM, 8k, CR = 3/4, GI = 1/4 | -88.5 | -85.1 | ||
| 64QAM, 8k, CR = 7/8, GI = 1/4 | -79.6 | -77.2 | ||
| Sensitivity, Gaussian Channel (UHF Band) |
QPSK, 8k, CR = 1/2, GI = 1/4 | -96.6 | -92.1 | dBm |
| 16QAM, 8k, CR = 3/4, GI = 1/4 | -87.9 | -82.6 | ||
| 64QAM, 8k, CR = 7/8, GI = 1/4 | -79.6 | -74.7 | ||
| Maximum Input, Gaussian Channel (VHF-III Band) |
64-QAM, 8k, CR = 2/3, GI = 1/8 | > 0 | -35 | dBm |
| 64-QAM, 8k, CR = 2/3, GI = 1/4 | > 0 | -35 | ||
| 64-QAM, 8k, CR = 3/4, GI = 1/8 | > 0 | -35 | ||
| Maximum Input, Gaussian Channel (UHF Band) |
64-QAM, 8k, CR = 2/3, GI = 1/8 | > 0 | -35 | dBm |
| 64-QAM, 8k, CR = 2/3, GI = 1/4 | > 0 | -35 | ||
| 64-QAM, 8k, CR = 3/4, GI = 1/8 | > 0 | -35 | ||
| Adjacent Channel Selectivity | N+1 DVB-T adjacent channel | 47 | ≥ 28 | dBc |
| N-1 DVB-T adjacent channel | 45 | |||
| N+2 DVB-T adjacent channel | 47.8 | ≥ 38 | ||
| N-2 DVB-T adjacent channel | 46 |
MBRAI指标比较
| Case | Category | Measure | MBRAI | Units | |
|---|---|---|---|---|---|
| Selectivity, S1 Pattern | N+1 | Category a, b1 | 48 | 37 | dBc |
| N+1 | Category b2, c | 45 | 37 | dBc | |
| N-1 | Category a, b1 | 54 | 37 | dBc | |
| N-1 | Category b2, c | 51 | 37 | dBc | |
| N+2 | Category a, b1 | 47 | 37 | dBc | |
| N+2 | Category b2, c | 55 | 37 | dBc | |
| N-2 | Category a, b1 | 45 | 37 | dBc | |
| N-2 | Category b2, c | 58 | 37 | dBc | |
| Selectivity, S2 Pattern | N+1 | Category a, b1 and b2, c | 39 | 29 | dBc |
| N-1 | Category a, b1 and b2, c | 38 | 29 | dBc | |
| N+2 | Category a, b1 | 43 | 40 | dBc | |
| N+2 | Category b2, c | 45 | 40 | dBc | |
| N-2 | Category a, b1 | 42 | 40 | dBc | |
| N-2 | Category b2, c | 44 | 40 | dBc | |
| Linearity L1 | – | Category a, b1 | 45.5 | 45 | dBc |
| – | Category b2, c | 47 | 45 | dBc | |
| Linearity L2 | – | Category a, b1 | 45.2 | 45 | dBc |
| – | Category b2, c | 47 | 45 | dBc | |
| Linearity L3 | – | Category a, b1 | 40.7 | 40 | dBc |
| – | Category b2, c | 42 | 40 | dBc |
全模式下的灵敏度指标
DVB-T全模式灵敏度指标的测试是基于7个同时输入的频道。
| VHF | UHF | |||||||
|---|---|---|---|---|---|---|---|---|
| Frequency (MHz) | 177.5 | 226.5 | 474 | 570 | 674 | 770 | 858 | |
| QPSK, 8k, CR = 1/2, GI = 1/4 | Sensitivity (dBm) | -97.3 | -97.3 | -97.2 | -97.1 | -96.7 | -96.5 | -96.2 |
| Max-Input (dBm) | > 0 | > 0 | > 0 | > 0 | > 0 | > 0 | > 0 | |
| QPSK, 8k, CR = 2/3, GI = 1/4 | Sensitivity (dBm) | -95.9 | -95.7 | -95.7 | -95.6 | -95.3 | -94.9 | -94.8 |
| QPSK, 8k, CR = 3/4, GI = 1/4 | Sensitivity (dBm) | -94.8 | -94.8 | -94.7 | -94.6 | -94.5 | -94.1 | -94 |
| QPSK, 8k, CR = 5/6, GI = 1/4 | Sensitivity (dBm) | -93.8 | -93.7 | -93.6 | -93.6 | -93.3 | -93 | -92.8 |
| QPSK, 8k, CR = 7/8, GI = 1/4 | Sensitivity (dBm) | -93.3 | -93.1 | -93.1 | -92.7 | -92.7 | -92.4 | -92.2 |
| 16QAM, 8k, CR = 1/2, GI = 1/4 | Sensitivity (dBm) | -91.7 | -91.7 | -91.5 | -91.5 | -91.4 | -90.9 | -90.7 |
| 16QAM, 8k, CR = 2/3, GI = 1/4 | Sensitivity (dBm) | -89.8 | -89.7 | -89.5 | -89.5 | -89.3 | -88.9 | -88.8 |
| 16QAM, 8k, CR = 3/4, GI = 1/4 | Sensitivity (dBm) | -88.6 | -88.3 | -88.4 | -88.1 | -88.1 | -87.5 | -87.3 |
| 16QAM, 8k, CR = 5/6, GI = 1/4 | Sensitivity (dBm) | -87.1 | -87 | -87 | -86.9 | -86.9 | -86.4 | -86.3 |
| 16QAM, 8k, CR = 7/8, GI = 1/4 | Sensitivity (dBm) | -86.4 | -85.7 | -86.1 | -85.9 | -85.7 | -85.4 | -85.6 |
| 64QAM, 8k, CR = 1/2, GI = 1/4 | Sensitivity (dBm) | -87 | -86.9 | -86.9 | -86.6 | -86.7 | -86.2 | -85.9 |
| 64QAM, 8k, CR = 2/3, GI = 1/4 | Sensitivity (dBm) | -84.1 | -84.1 | -83.8 | -83.8 | -83.7 | -83.3 | -83.2 |
| 64QAM, 8k, CR = 3/4, GI = 1/4 | Sensitivity (dBm) | -82.5 | -82.2 | -82.3 | -82.4 | -81.8 | -81.5 | -81.4 |
| 64QAM, 8k, CR = 5/6, GI = 1/4 | Sensitivity (dBm) | -80.9 | -80.9 | -80.7 | -80.7 | -80.4 | -80.2 | -79.8 |
| 64QAM, 8k, CR = 7/8, GI = 1/4 | Sensitivity (dBm) | -79.9 | -79.7 | -79.5 | -79.5 | -79 | -78.9 | -78.8 |
| Max-Input (dBm) | -2 | -0.2 | > 0 | > 0 | > 0 | > 0 | > 0 | |
供电电流
供电电流的测试条件包含了射频输入端和TV输出端的75Ω端接负载、正常工作模式并且系统调谐至信道69 (858MHz)。
| Parameter | Conditions | Measured | Units |
|---|---|---|---|
| 5V LNA Supply Current | 12 | mA | |
| 5V for Tuner and LNA* | {8k, QPSK, CR = 1/2, GI = 1/4} | 196 | mA |
| {8k, 64QAM, CR = 7/8, GI = 1/4} | 196 | mA | |
| 3.3V Digital Supply Current for Demodulator | {8k, QPSK, CR = 1/2, GI = 1/4} | 8 | mA |
| {8k, 64QAM, CR = 7/8, GI = 1/4} | 10 | mA | |
| 2.5V Analog Supply Current for Demodulator | {8k, QPSK, CR = 1/2, GI = 1/4} | 36 | mA |
| {8k, 64QAM, CR = 7/8, GI = 1/4} | 36 | mA | |
| 1.0V Digital Supply Current for Demodulator | {8k, QPSK, CR = 1/2, GI = 1/4} | 90 | mA |
| {8k, 64QAM, CR = 7/8, GI = 1/4} | 92 | mA | |
| 1.0V Analog Supply Current for Demodulator | {8k, QPSK, CR = 1/2, GI = 1/4} | 3 | mA |
| {8k, 64QAM, CR = 7/8, GI = 1/4} | 3 | mA |
*注：MAX3580所需的3.3V供电电源通过一个LDO从5V降压获得。
详细说明
本DVB-T接收电路参考设计满足NorDig 1.0.2及MBRAI标准。此电路可以用于地面接收的机顶盒，封装于NIM调谐器的尺寸之内。此参考设计覆盖了VHF-III频段(170MHz至230MHz)及UHF频段(470MHz至870MHz)，能够与一个接口板相连完成系统测试。
本参考设计包含：
- 一个用于实现有源环通的分离低噪声放大电路。环通具有14dB的增益和小于3.5dB的噪声系数，并且消耗60mW的功率。
- 一个完全集成的MAX3580硅调谐器芯片，包含低噪声放大器、射频/中频可调增益放大器、混频器以及基带低通滤波器。该调谐器芯片只需要单路3.3V供电以及少量无源器件便可完成一个完整的DVB-T射频前端电路。
- 一个满足DVB-T/H标准的解调芯片，可以完全支持DVB-T和DVB-H标准的帧结构、信道编码和解调。