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| 型号： | LMV242MDA |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 通信及网络 |
| 英文描述： | MICA RoHS Compliant: No |
| 中文描述： | SPECIALTY TELECOM CIRCUIT, UUC10 |
| 封装： | DIE-10 |
| 文件页数： | 11/16页 |
| 文件大小： | 560K |
| 代理商： | LMV242MDA |
Application Section
POWER CONTROL PRINCIPLES
The LMV242 is a member of the power loop controller family
of National Semiconductor, for quad-band TDMA/GSM solu-
tions. The typical application diagram demonstrates a basic
approach for implementing the quad-band solution around
an RF Power Amplifier (PA). The LMV242 contains a 50 dB
Logamp detector and interfaces directly with the directional
coupler.
The LMV242 Base Band (control-) interface consists of 3
signals: TX_EN to enable the device, BS to select either
output 1 or output 2 and V
RAMP
to set the RF output power to
the specified level. The LMV242 gives maximum flexibility to
meet GSM frequency- and time mask criteria for many dif-
ferent single supply Power Amplifier types like HBT or Mes-
FET in GaAs, SiGe or Si technology. This is accomplished by
the programmable Ramp characteristic from the Base Band
and the TX_EN signal along with the external compensation
capacitor.
POWER AMPLIFIER CONTROLLED LOOP
This section gives a general overview and understanding of
how a typical Power Amplifier control loop works and how to
solve the most common problems confronted in the design.
General Overview
The key benefit of a PA control loop circuit is its immunity to
changes in the PA gain control function. When a PA control-
ler is used, the relationship between gain and gain control
voltage (V
) of the PA is of no consequence to the overall
transfer function. It is a function of the controller’s V
voltage. Based upon the value of V
, the PA controller
will set the gain control voltage of the PA to a level that is
necessary to produce the desired output level. Any tempera-
ture dependency in the PA gain control function will be
eliminated. Also, non-linearity’s in the gain transfer function
of the PA do not appear in the overall transfer function (P
OUT
vs. V
RAMP
). The only requirement is that the gain control
function of the PA has to be monotonic. To achieve this, it is
crucial, that the LMV242’s detector is temperature stable.
Typical PA Closed Loop Control Setup
A typical setup of PA control loop is depicted in
Figure 1
.
Beginning at the output of the Power Amplifier (PA), this
signal is fed, usually via a directional coupler, to a detector.
The error between the detector output current I
and the
ramp current I
, representing the selected power setting,
drives the inverting input of an op amp, configured as an
integrator. A reference voltage drives the non-inverting input
of the op amp. Finally the output of the integrator op amp
drives the gain control input of the power amplifier, which
sets the output power. The loop is stabilized when I
is
equal to I
RAMP
. Lets examine how this circuit works in detail.
20079528
FIGURE 1. PA Control Loop
L
www.national.com
11
相关PDF资料 |
PDF描述 |
|---|---|
| LMV242LD | Dual Output, Quad-Band GSM/GPRS Power Amplifier Controller |
| LMV242MWA | Dual Output, Quad-Band GSM/GPRS Power Amplifier Controller |
| LMV242LDX | Silver Mica Capacitor; Capacitance:510pF; Capacitance Tolerance: 5%; Series:CDV30; Voltage Rating:1500VDC; Capacitor Dielectric Material:Mica; Termination:Radial Leaded; Lead Pitch:11.1mm; Leaded Process Compatible:No RoHS Compliant: No |
| LMV242 | Dual Output, Quad-Band GSM/GPRS Power Amplifier Controller |
| LMV301 | Low Input Bias Current, 1.8V Op Amp w/ Rail-to-Rail Output |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LMV242MEA DIE | 制造商:Texas Instruments 功能描述: |
| LMV242MWA | 制造商:NSC 制造商全称:National Semiconductor 功能描述:Dual Output, Quad-Band GSM/GPRS Power Amplifier Controller |
| LMV243 | 制造商:NSC 制造商全称:National Semiconductor 功能描述:Single-Channel, Quad-Band GSM Power Controller in micro SMD |
| LMV243BL | 功能描述:IC GSM POWER CONTROLLR 8USMD RoHS:否 类别:RF/IF 和 RFID >> RF 电源控制器 IC 系列:- 标准包装:3,000 系列:- RF 型:GSM 频率:450MHz ~ 2GHz 特点:四频带 封装/外壳:8-VFBGA 供应商设备封装:8-MicroSMD（1.51x1.51） 包装:带卷 (TR) 其它名称:LMV243BLX |
| LMV243BLEVAL | 功能描述:电源管理IC开发工具 LMV243BL EVAL BOARD RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
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