- 您现在的位置：买卖IC网 > PDF目录358884 > LMV232TLX (NATIONAL SEMICONDUCTOR CORP) Dual-Channel Integrated Mean Square Power Detector for CDMA & WCDMA PDF资料下载
参数资料
| 型号： | LMV232TLX |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 衰减器 |
| 英文描述： | Dual-Channel Integrated Mean Square Power Detector for CDMA & WCDMA |
| 中文描述： | 50 MHz - 2000 MHz RF/MICROWAVE LINEAR DETECTOR |
| 封装： | 1.50 X 1.50 MM, 0.60 MM HEIGHT, LEAD FREE, MO-211DD, MICRO SMD, 8 PIN |
| 文件页数： | 9/13页 |
| 文件大小： | 779K |
| 代理商： | LMV232TLX |
Application Notes
The LMV232 mean square power detector is particularly
suited for accurate power measurement of RF modulated
signals that exhibit large peak to average ratios, i.e. large
variations of the signal envelope. Such noise-like signals are
encountered e.g. in CDMA and Wide-band CDMA cell-
phones. Many power detection circuits, particularly those
devised for constant-envelope modulated signals as in
GSM, are based on peak detection and provide accurate
power measurements for constant envelope or low-crest
factor (ratio of peak to RMS) signals only. Such detectors are
therefore not particularly suited for CDMA and WCDMA ap-
plications.
TYPICAL APPLICATION
The LMV232 is especially suited for CDMA and WCDMA
applications with 2 Power Amplifiers (PA’s). A typical setup is
given in
Figure 1
. The output power of one PAis measured at
a time, depending on the bandselect pin (BS). If the BS =
High RF
1 is used for measurements, if BS = Low RF
2 is
used. The measured output voltage of the LMV232 is read
by the ADC of the baseband chip and the gain of the PA gain
is adjusted if necessary. With an input impedance of 50
,
the LMV232 can be directly connected to a 20 dB directional
coupler without the need for an additional external attenua-
tor. The setup can be adjusted to various PA output ranges
by selection of a directional coupler or insertion of an addi-
tional (resistive) attenuator between the coupler outputs and
the LMV232 RF inputs.
The LMV232 conversion gain and bandwidth are configured
by a resistor and a capacitor. Resistor R1 sets the conver-
sion gain from RF
to the output voltage. A higher resistor
value will result in a higher conversion gain. The maximum
dynamic range is achieved when the resistor value is as high
as possible, i.e. the output signal just doesn’t clip and the
voltage stays within the baseband ADC input range. The
filter bandwidth is adjusted by capacitor C1. The capacitor
value should be chosen such that the response time of the
device is fast enough and modulation on the RF input signal
is not visible at the output (ripple suppression). The 3 dB
filter bandwidth of the output filter is determined by the time
constant R1*C1. Generally a capacitor value of 1.5 nF is a
good choice.
PEAK TO AVERAGE RATIO SENSITIVITY
The LMV232 power detector provides an accurate power
measurement for arbitrary input signals, low and high peak-
to-average ratios and crest factors. This is because its op-
eration is not based on peak detection, but on direct deter-
mination of the mean square value. This is the most accurate
power measurement, since it exactly implements the defini-
tion of power. A mean-square detector measures V
RMS2
for
all waveforms. Peak detection is less accurate because the
relation between peak detection and mean square detection
depends on the waveform. A peak detector measures P =
V
PEAK2
for all waveforms, while it should measures P =
V
PEAK2
/2 (for R = 1
) for a sine wave and P = V
PEAK2
/3 for
a triangle wave for instance. For a CDMA signal, the mea-
surement error can be in the order of 5 to 6 dB. For many
wave forms, specially those with high peak-to-average ra-
tios, peak detection is not accurate enough and therefore a
mean square detector is recommended.
MEAN SQUARE CONFORMANCE ERROR
The LMV232 is a mean square detector and therefore
should have an output voltage (in Volts) that linearly relates
to the RF input power (in mW). The input referred error, with
respect to an ideal linear mean square detector, is deter-
mined as a measure for the accuracy of the detector.
20127801
FIGURE 1. Typical Application
L
www.national.com
9
相关PDF资料 |
PDF描述 |
|---|---|
| LMV242MDA | MICA RoHS Compliant: No |
| 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 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LMV232TLX/NOPB | 功能描述:射频检测器 RoHS:否 制造商:Skyworks Solutions, Inc. 配置: 频率范围:650 MHz to 3 GHz 最大二极管电容: 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:SC-88 封装:Reel |
| LMV241C WAF | 制造商:Texas Instruments 功能描述: |
| LMV242 | 制造商:NSC 制造商全称:National Semiconductor 功能描述:Dual Output, Quad-Band GSM/GPRS Power Amplifier Controller |
| LMV242LD | 功能描述:射频检测器 RoHS:否 制造商:Skyworks Solutions, Inc. 配置: 频率范围:650 MHz to 3 GHz 最大二极管电容: 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:SC-88 封装:Reel |
| LMV242LD/NOPB | 功能描述:射频检测器 RoHS:否 制造商:Skyworks Solutions, Inc. 配置: 频率范围:650 MHz to 3 GHz 最大二极管电容: 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:SC-88 封装:Reel |
发布紧急采购，3分钟左右您将得到回复。