RFRXD0920-I/LQ【PDF 18/32 页】MODULE RCVR 868/915MHZ ASK/FSK

您好，
买卖IC网欢迎您。
请登录
免费注册

14页 15页 16页 17页 [18页]19页 20页 21页 22页

rfRXD0420/0920

3.3

Frequency Shift Keying (FSK)

FIGURE 3-14: LC DISCRIMINATOR

Figure 3-13 illustrates an example FSK application

circuit.

EXAMPLE CIRCUIT

3.3.1

IF FILTER CONSIDERATIONS

R1

4.7 k ?

As mentioned in the Section 3.1 above, IF filter band-

width selection is a function of:

C3

0-56 pF

? modulation (ASK, FSK or FM)

? signal bandwidth

? frequency and temperature tolerances of the

transmitter and receiver components

C1

1.0 pF

L1

3.3 μ H

C2

680 pF

The occupied bandwidth of binary FSK signals is 2

times the peak frequency deviation plus 2 times the

signal bandwidth. For example, if the data rate is 2400

bits per second Manchester encoded, the signal band-

width is 4800 baud or 1200 Hz, and if the peak

15

16

frequency deviation is 24 kHz, the minimum bandwidth

of the IF filter is:

IF BW min = (2 x 2400) + (2 x 24000)

IF BW min = 52800 Hz

Add to this value the frequency and temperature

tolerances of the transmitter and receiver components.

FSK signals are more sensitive to group delay varia-

tions of the IF filter. Therefore, a filter with a low group

3.3.2.2 Ceramic Discriminator

A no-tune solution can be constructed with a ceramic

discriminator. Figure 3-15 illustrates an example

ceramic discriminator circuit.

The ceramic discriminator acts as a parallel tuned

circuit at the IF frequency (for example, 10.7 MHz). The

parallel capacitor C3 tunes the ceramic resonator. The

high Q of this circuit enables higher output of the detec-

tor for small frequency deviations. However, smaller

delay variation should be used. As an alternative, a

frequency deviations

require better frequency

filter with wider than required bandwidth can be used

because the group delay variation in the center of the

bandpass will be relatively constant.

tolerances at the transmitter and receiver.

In order to detect wider deviation or off-frequency

signals, the detector bandwidth has to be increased.

3.3.2

FSK DETECTOR

This can be accomplished by reducing the Q of the

tuned circuit. One method is to parallel a resistor

The demodulator (DEMOD) section consists of a phase

detector (MIXER2) and amplifier creating a quadrature

detector (also known as a phase coincidence detector)

to demodulate the IF signal in FSK and FM modulation

applications. The in-phase signal comes directly from

the output of the IF limiting amplifier to MIXER2. The

quadrature signal is created by an external tuned circuit

from the output of the IF limiting amplifier (2IF OUT , Pin

15) AC-coupled to the MIXER2 DEM IN (Pin 16) input.

across the ceramic discriminator. A second is to

increase the value of the coupling capacitor C1

increasing the load on the detector. The result of

reducing the Q of the discriminator will be that the

detector output will be smaller.

FIGURE 3-15: CERAMIC DISCRIMINATOR

EXAMPLE CIRCUIT

3.3.2.1

LC Discriminator

F1

CERAMIC DISCRIMINATOR

The external tuned circuit can be constructed from

simple inductor-capacitor (LC) components. This type

circuit produces and excellent output. However, one of

the elements (L or C) must be tunable. Figure 3-14

illustrates an example LC discriminator circuit using a

tunable capacitor. A similar circuit with a tunable induc-

C1

1.0 pF

C3

10-12 pF

C2

680 pF

tor is also possible. Resistor R1 = 4.7 k ? reduces the

Q of the circuit so that frequency deviations of up to 75

kHz can be demodulated.

15

16

DS70090A-page 18

Preliminary

? 2003 Microchip Technology Inc.

发布紧急采购，3分钟左右您将得到回复。

采购需求

(若只采购一条型号，填写一行即可)

*型号	*数量	厂商	批号	封装

添加更多采购

我的联系方式

*

*

*

相关PDF资料

RHK005N03T146 MOSFET N-CH 30V 500MA SOT-346

RHP020N06T100 MOSFET N-CH 60V 2A SOT-89

RHP030N03T100 MOSFET N-CH 30V 3A SOT-89

RI-TRP-WEHP-30 RFID GLASS TRANSP R/W 80BIT 23MM

RJ45-XLRM CONVERTER LEAD RJ45-XLR MALE

RJK005N03T146 MOSFET N-CH 30V 500MA SOT-346

RJK0230DPA-00#J5A MOSFET DL N-CH 25V 20A WPAK

RJK0353DSP-00#J0 MOSFET N-CH 30V 18A 8-SOP

相关代理商/技术参数

RFRXD0920T-I/LQ 功能描述:射频收发器 32 LD 800-930 MHz RF RoHS:否制造商:Atmel 频率范围:2322 MHz to 2527 MHz 最大数据速率:2000 Kbps 调制格式:OQPSK 输出功率:4 dBm 类型: 工作电源电压:1.8 V to 3.6 V 最大工作温度:+ 85 C 接口类型:SPI 封装 / 箱体:QFN-32 封装:Tray

RFS04ZG-M6 制造商:Power-One 功能描述:

RFS04ZG-M6G 制造商:Power-One 功能描述:RFS Series 20 W Single Output 5 V DC/DC Converter Power Supply - Surface Mount

RFS062PJ150CS 功能描述:RES ARRAY 2 RES 15 OHM 0603 制造商:samsung electro-mechanics 系列:RFS 包装:剪切带（CT）零件状态:在售电路类型:隔离电阻（欧姆）:15 容差:±5% 电阻器数:2 引脚数:4 每元件功率:31.25mW 温度系数:±200ppm/°C 工作温度:-55°C ~ 125°C 应用:- 安装类型:表面贴装封装/外壳:0302（0805 公制），长边端子供应商器件封装:603 大小/尺寸:0.032" 长 x 0.024" 宽（0.80mm x 0.60mm）高度 - 安装（最大值）:0.013"（0.33mm）标准包装:1

RFS062PJ220CS 功能描述:RES ARRAY 2 RES 22 OHM 0603 制造商:samsung electro-mechanics 系列:RFS 包装:剪切带（CT）零件状态:在售电路类型:隔离电阻（欧姆）:22 容差:±5% 电阻器数:2 引脚数:4 每元件功率:31.25mW 温度系数:±200ppm/°C 工作温度:-55°C ~ 125°C 应用:- 安装类型:表面贴装封装/外壳:0302（0805 公制），长边端子供应商器件封装:603 大小/尺寸:0.032" 长 x 0.024" 宽（0.80mm x 0.60mm）高度 - 安装（最大值）:0.013"（0.33mm）标准包装:1

RFS062PJ240CS 功能描述:RES ARRAY 2 RES 24 OHM 0603 制造商:samsung electro-mechanics 系列:RFS 包装:剪切带（CT）零件状态:在售电路类型:隔离电阻（欧姆）:24 容差:±5% 电阻器数:2 引脚数:4 每元件功率:31.25mW 温度系数:±200ppm/°C 工作温度:-55°C ~ 125°C 应用:- 安装类型:表面贴装封装/外壳:0302（0805 公制），长边端子供应商器件封装:603 大小/尺寸:0.032" 长 x 0.024" 宽（0.80mm x 0.60mm）高度 - 安装（最大值）:0.013"（0.33mm）标准包装:1

RFS062PJ270CS 功能描述:RES ARRAY 2 RES 27 OHM 0603 制造商:samsung electro-mechanics 系列:RFS 包装:剪切带（CT）零件状态:在售电路类型:隔离电阻（欧姆）:27 容差:±5% 电阻器数:2 引脚数:4 每元件功率:31.25mW 温度系数:±200ppm/°C 工作温度:-55°C ~ 125°C 应用:- 安装类型:表面贴装封装/外壳:0302（0805 公制），长边端子供应商器件封装:603 大小/尺寸:0.032" 长 x 0.024" 宽（0.80mm x 0.60mm）高度 - 安装（最大值）:0.013"（0.33mm）标准包装:1

RFS062PJ300CS 制造商:Samsung Electro-Mechanics 功能描述:- Tape and Reel