**7. Application of noise budget concept**

Finally, we will propose the Noise Budget concept for platform noise suppression. The noise budget for the wireless communication device can be considered as near-field EMC limit. Noise budget is a powerful tool to apply for the wireless product from initial design stage, QA, QC, and all the way to final production testing. For communications community and RF device manufactures, the link budget is established for system planning, therefore most of RF engineers understand that the characteristics of antenna, LNA, mixer play important role for range and coverage extending. However the parameters discussed in link budget are all about signal transmission alone, another important component parameter related to noise level, the Noise Budget, is the missing puzzle for the system integration.

### **7.1 Introduction to noise budget concept**

Since the electronics of the notebook or labtop are the interference source for RF wireless device as discussed earlier. This final section covers some design guidelines and EMI measuring techniques of components, because EMI from internal ICs is also a major contribution to impact the RF performance. The primary purpose here is to address the idea of "Component Noise Budget for Wireless Integration". The concept of noise budget for devices on wireless communication product stems from the link-budget for RF Tx/Rx performance. It also borrows the idea from EMC testing requirements for automobile industry to identify the potential interference sources that might cause safety problem and


Finally, we will propose the Noise Budget concept for platform noise suppression. The noise budget for the wireless communication device can be considered as near-field EMC limit. Noise budget is a powerful tool to apply for the wireless product from initial design stage, QA, QC, and all the way to final production testing. For communications community and RF device manufactures, the link budget is established for system planning, therefore most of RF engineers understand that the characteristics of antenna, LNA, mixer play important role for range and coverage extending. However the parameters discussed in link budget are all about signal transmission alone, another important component parameter related to

Since the electronics of the notebook or labtop are the interference source for RF wireless device as discussed earlier. This final section covers some design guidelines and EMI measuring techniques of components, because EMI from internal ICs is also a major contribution to impact the RF performance. The primary purpose here is to address the idea of "Component Noise Budget for Wireless Integration". The concept of noise budget for devices on wireless communication product stems from the link-budget for RF Tx/Rx performance. It also borrows the idea from EMC testing requirements for automobile industry to identify the potential interference sources that might cause safety problem and

noise level, the Noise Budget, is the missing puzzle for the system integration.

Throughput (Mbs)

Fig. 48. Embedded antenna mini-coaxial cable and noise distribution.

Fig. 49. Circuit ground and chassis ground.

**7. Application of noise budget concept** 

**7.1 Introduction to noise budget concept** 

Intensity (dBm)

2434 2435 2436 2437 2438 2439 2440

Noise level

Frequency (MHz)

40 46 52 58 64 70 76 82 88 94 100

Annenuation (dB)

Original - 0° Rotate ant - 0° Original - 90° Rotate ant- 90°

Original Path 2 Path 3 copper film Path 4 Rotate ant

IEEE 802.11g RX

thus to provide design guideline for compliance. The noise budget concept helps system designers to manage the EMC issues, as early as possible, such as coupling mechanisms, module placement, grounding, and routing for EMC test. The methodology is intended to develop modular architecture of analysis to accelerate system design and also provide the solutions for potential problems to improve performance in all aspects.

The preliminary goal of this research is to establish the noise budget for components and devices on laptop computer for further RF sensitivity analysis. To utilize the near-field EM scanner to detect the EMI sources on laptop, we can locate the major noise sources in 2D hot-spot distribution graph. From the emission levels and locations of the noisy components, we can figure out their impact on throughput and receiving sensitivity of wireless communication and find the solution to improve performance. The final goal of noise budget, however, is to establish the EMI limits for each digital components related to layout location, it would therefore help designers to choose the appropriate components for optimal placement and cost consideration to meet product requirement. The application of noise budget accompanied with near-field surface scanner not only can locate the EMI source and further to solve the problem, but also can utilize the EM analysis to improve the design efficiency and the performance of wireless communications.

The factors that would affect the receiving performance of a wireless receiver can be illustrate in Figure 50. Table 7 shows the relationship between link budget and noise budget for wireless communication system implementation.

Fig. 50. Factors affecting the receiving performance of a wireless receiver.


Table 7. LINK budget (left) vs. NOISE budget (right).

The common interference noise sources on integrated high-speed digital wireless communication product nowadays include: CPU, LCD panel, Memory, digital components, high-speed I/O interconnect, wires and cables, etc. The modules' placement of the test setup is illustrated in Figure 51. The above mentioned noises are usually coupled to nearby sensitive devices through radiation, conduction, or crosstalk. The resulted EMI problem will further degrade the system sensitivity and performance for wireless communications.

After the emitted noise level and corresponding location of each component has been identified, we investigate the effect of component placement on in-band noise level at antenna port and thus the performance of wireless communications by changing distance between antenna and component under test. We can further find the optimal orientation and location of component to improve overall communications performance[9,10].

Because a variety of digital components exist inside laptop computer, we focus on LCD Panel that is equipped in all computers and usually placed in the proximity of antennas. To investigate the effect of various operation modes, (such as off, standby, and key-in alphbat H pattern mode) on noise level at the antenna port, we first arranged the test setup as laptop normally working and scanned the ambient noise.

To clarify the influence of LCD panel noise on antenna port and thus receiving sensitivity, we first fixed the function setting on computer to avoid effect from software's inconsistent running mode. After activating the LCD Panel for various testing mode, we measured the noise spectrum at antenna port to find out the interference frequencies and then use nearfield probes to scan the EMI noise from LVDS cables, connectors, and driver ICs of the LCD panel control circuits. Finally, we can investigate the impact of different LCD operation mode on the frequency bands of wireless communications by analyzing the measured throughput results.

Fig. 51. Internal layout of laptop computer.

214 Wireless Communications and Networks – Recent Advances

The common interference noise sources on integrated high-speed digital wireless communication product nowadays include: CPU, LCD panel, Memory, digital components, high-speed I/O interconnect, wires and cables, etc. The modules' placement of the test setup is illustrated in Figure 51. The above mentioned noises are usually coupled to nearby sensitive devices through radiation, conduction, or crosstalk. The resulted EMI problem will further degrade the system sensitivity and performance for

After the emitted noise level and corresponding location of each component has been identified, we investigate the effect of component placement on in-band noise level at antenna port and thus the performance of wireless communications by changing distance between antenna and component under test. We can further find the optimal orientation

Because a variety of digital components exist inside laptop computer, we focus on LCD Panel that is equipped in all computers and usually placed in the proximity of antennas. To investigate the effect of various operation modes, (such as off, standby, and key-in alphbat H pattern mode) on noise level at the antenna port, we first arranged the test setup as laptop

To clarify the influence of LCD panel noise on antenna port and thus receiving sensitivity, we first fixed the function setting on computer to avoid effect from software's inconsistent running mode. After activating the LCD Panel for various testing mode, we measured the noise spectrum at antenna port to find out the interference frequencies and then use nearfield probes to scan the EMI noise from LVDS cables, connectors, and driver ICs of the LCD panel control circuits. Finally, we can investigate the impact of different LCD operation mode on the frequency bands of wireless communications by analyzing the measured

and location of component to improve overall communications performance[9,10].

Table 7. LINK budget (left) vs. NOISE budget (right).

normally working and scanned the ambient noise.

wireless communications.

throughput results.
