原标题：基于Sliconlabs si4463的WMRNET-I I 新国网高性能电能表抄表解决方案

　　WMRNET-II网络是专为新国网电能表集抄开发的无线自组织网络系统，网络采用非常稳定的MESH网络结构，组网速度、抄表速度快，一次抄表成功率非常高，抄表成功率超过99%。网络内模块节点之间通讯距离超过1千米，室外网络系统覆盖半径超过6千米。同时，网络具有极强的穿透能力，非常适用于普通工业楼宇群和大型高层建筑社区。

　　网络工作于433MHz或470MHz频段，由无线集中器APC920和无线网络节点模块APC320N或APC320G组成。其中APC920与APC320G符合新国网和北京标准，适用于国内标准单向、三相电能表，与新国网电表无缝兼容;APC920与APC320N适用于高性能非国网电能表。

　　网络系统采用主从式机制，集中器控制网络的一切活动。一个集中器可以控制1024个节点，可支持10级路由。系统在上电以后，系统自动组建网络，自动维护和优化网络路由，无需用户干预，自动发现和删除节点。新节点在一定时间内可以被网络发现，节点地址被被网络识别后将节点加入网络当中，被移除节点的路由等信息在可设定的时间内被删除。任意节点既可以作为子节点，又可以作为父节点。任意节点支持多个父节点，任意节点有多条到达集中器的路由，并且节点传输数据时动态的选择优化路由，任意节点都具有路由器与中继功能。处于级数比较多的节点，向集中器传输数据的时候，通过上一级父节点转发数据，然后它的父节点再通过其它节点传输到集中器，每个节点有多个父节点，使网络更加可靠，同时扩大了网络的覆盖面积。若在网络中若干个节点出现故障，或者被移除，丝毫不会影响网络的通信，集中器可以通过其它节点找到失去父节点的节点。通过集中器发送命令，可以了解网络节点的数量、地址、级数以及路由等情况。

【Si4463】

Features

▪ Frequency range = 142–1050 MHz

▪ Receive sensitivity = –129 dBm

▪ Modulation

》(G)FSK, 4(G)FSK, (G)MSK

》OOK

▪ Max output power

》+20 dBm (Si4463)

》+16 dBm (Si4461)

》+13 dBm (Si4460)

▪ PA support for +27 or +30 dBm

▪ Low active power consumption

》10/13 mA RX

》18 mA TX at +10 dBm (Si4460)

▪ Ultra low current powerdown modes

》30 nA shutdown, 40 nA standby

▪ Preamble sense mode

》6 mA average RX current at

1.2 kbps

》10 µA average RX current at

50 kbps and 1 sec sleep interval

▪ Fast preamble detection

》1 byte preamble detection

▪ Data rate = 100 bps to 1 Mbps

▪ Fast wake and hop times

▪ Power supply = 1.8 to 3.8 V

▪ Excellent selectivity performance

》69 dB adjacent channel

》79 dB blocking at 1 MHz

▪ Antenna diversity and T/R switch control

▪ Highly configurable packet handler

▪ TX and RX 64 byte FIFOs

》129 bytes dedicated Tx or Rx

▪ Auto frequency control (AFC)

▪ Automatic gain control (AGC)

▪ Low BOM

▪ Low battery detector

▪ Temperature sensor

▪ 20-Pin QFN package

▪ IEEE 802.15.4g and WMBus compliant

▪ Suitable for FCC Part 90 Mask D, FCC

part 15.247, 15,231, 15,249, ARIB T-108,

T-96, T-67, RCR STD-30, China

regulatory

▪ ETSI Category I Operation EN300 220

Applications

Smart metering (802.15.4g and WMBus)

▪ Remote control

▪ Home security and alarm

▪ Telemetry

▪ Garage and gate openers

▪ Remote keyless entry

▪ Home automation

▪ Industrial control

▪ Sensor networks

▪ Health monitors

▪ Electronic shelf labels

Description

Silicon Laboratories' Si446x devices are high-performance, low-currenttransceivers covering the sub-GHz frequency bands from 142 to 1050 MHz. Theradios are part of the EZRadioPRO® family, which includes a complete line oftransmitters, receivers, and transceivers covering a wide range of applications. Allparts offer outstanding sensitivity of –129 dBm while achieving extremely lowactive and standby current consumption. The Si4463/61/60 offers frequencycoverage in all major bands. The Si446x includes optimal phase noise, blocking,and selectivity performance for narrow band and wireless MBus licensed bandapplications, such as FCC Part90 and 169 MHz wireless Mbus. The 69 dBadjacent channel selectivity with 12.5 kHz channel spacing ensures robustreceive operation in harsh RF conditions, which is particularly important for narrowband operation. The Si4463 offers exceptional output power of up to +20 dBmwith outstanding TX efficiency. The high output power and sensitivity results in anindustry-leading link budget of 146 dB allowing extended ranges and highly robustcommunication links. The Si4460 active mode TX current consumption of 18 mAat +10 dBm and RX current of 10 mA coupled with extremely low standby currentand fast wake times ensure extended battery life in the most demandingapplications. The Si4463 can achieve up to +27 dBm output power with built-inramping control of a low-cost external FET. The devices can meet worldwideregulatory standards: FCC, ETSI, wireless MBus, and ARIB. All devices aredesigned to be compliant with 802.15.4g and WMbus smart metering standards.

The devices are highly flexible and can be configured via the WirelessDevelopment Suite (WDS) available on the Silicon Labs website.

Si446x/Si4362 RX LNA Matching

1. Introduction

The purpose of this application note is to provide a description of the impedance matching of the RX differential low

noise amplifier (LNA) on the Si446x/Si4362 family of RFICs.

It is desired to simultaneously achieve two goals with the matching network:

▪Match the LNA input to the antenna source impedance (e.g., 50 

▪Provide a single-ended-to-differential conversion function (i.e., a balun)

The matching procedure outlined in this document provides for achieving the goals listed above.

For those users who are not interested in the theoretical derivation of the match network, but are just concerned

with quickly obtaining matching component values, refer to the Summary Tables shown in "4.1.7. Summary Tables

of 3-Element Match Network Component Values vs. Frequency" on page 12 and "4.2.7. Summary Tables of 4-

Element Match Network Component Values vs. Frequency" on page 19.

Measurements were performed on the Si4461-B0 chip but are applicable to other members of the Si446x family of

chips (e.g. Si446x-B1, C0, C1, C2 and the Si4362 chip).

2. Match Network Topology

The LNA on the Si446x/Si4362 family of chips is designed as a differential amplifier and thus has two input pins

(RXp and RXn) on the RFIC. It is necessary to design a network that not only provides a conjugate match to the

input impedance of the LNA but also provides a balanced-to-unbalanced conversion function (i.e., a balun).

The LNA design is differential and thus the RXp and the RXn input pins may be considered interchangeable.

Although the figures in this document may show the matching components connected to the RXp/RXn pins in a

certain fashion, the pin connections may be reversed without change in functionality.

Use of two basic matching network topologies will be considered within this application note.

2.1. Three-Element Match Network

The simplest match network that may be fabricated from discrete components is comprised of three discrete

elements. Two forms of the 3-element match network may be constructed: one with a highpass filter (HPF)

response, and one with a lowpass filter (LPF) response. However, the form with a lowpass filter response is not

realizable at all frequencies and input impedances. As a result, only the form with a highpass filter response is

discussed within this document.

A 3-element (CR1-LR1-CR2) HPF matching network is shown in Figure 1. This matching network has the virtue of

requiring a minimum number of components but results in slightly sub-optimal performance. It is not theoretically

possible to achieve a perfectly balanced single-ended-to-differential conversion function with this matching network

for input impedances with finite values of RLNA. As will be demonstrated, the waveforms obtained at the RXp and

RXn inputs to the RFIC will not be exactly 180° out of phase; the result is a very slight loss in conversion gain in the

LNA and a small drop in overall sensitivity of the RFIC. The reduction in performance is typically less than 0.5 dB;

many customers may view this as an acceptable trade-off for the reduction in the bill of materials (BOM).

The RXp and RXn inputs of the Si446x/Si4362 RX LNA internally contain high value (~15 k) pull-down resistors

to GND. As a result, supplying a DC voltage to these pins is not recommended; use of external AC-coupling to

these pins is suggested. This is inherently supplied by capacitor CR2 of Figure 1.