參數(shù)資料
型號： SA614AN
廠商： NXP SEMICONDUCTORS
元件分類： 接收器
英文描述： R-78Axx-0.5SMD Series - Innoline Regulated DC-DC Converters; Output Voltage (Vdc): 3.3V; Output Current (A): 0.5A; Features: Efficiency up to 97%, Non isolated, no need for heatsinks; SMD Package; Adjustable Output Voltage; Wide input range.(4.75V ~ 34V); Short circuit protection, Thermal shutdown; Remote On/Off Control; UL94V-0 Package Material; Very Low Shutdown Current; See Positive-to Negative Converter Application Note for use as a voltage inverter (alternative to LM79xx Linear)
中文描述： FM, AUDIO DEMODULATOR, PDIP16
封裝： 0.300 INCH, PLASTIC, DIP-16
文件頁數(shù)： 9/14頁
文件大?。?/td> 216K
代理商： SA614AN
Philips Semiconductors
Product specification
SA614A
Low power FM IF system
1997 Nov 07
9
input level, the limited signal will begin to dominate the regeneration,
and the demodulator will begin to operate in a “normal” manner.
There are three primary ways to deal with regeneration: (1)
Minimize the feedback by gain stage isolation, (2) lower the stage
input impedances, thus increasing the feedback attenuation factor,
and (3) reduce the gain. Gain reduction can effectively be
accomplished by adding attenuation between stages. This can also
lower the input impedance if well planned. Examples of
impedance/gain adjustment are shown in Figure 9. Reduced gain
will result in reduced limiting sensitivity.
A feature of the SA614A IF amplifiers, which is not specified, is low
phase shift. The SA614A is fabricated with a 10GHz process with
very small collector capacitance. It is advantageous in some
applications that the phase shift changes only a few degrees over a
wide range of signal input amplitudes.
Stability Considerations
The high gain and bandwidth of the SA614A in combination with its
very low currents permit circuit implementation with superior
performance. However, stability must be maintained and, to do that,
every possible feedback mechanism must be addressed. These
mechanisms are: 1) Supply lines and ground, 2) stray layout
inductances and capacitances, 3) radiated fields, and 4) phase shift.
As the system IF increases, so must the attention to fields and
strays. However, ground and supply loops cannot be overlooked,
especially at lower frequencies. Even at 455kHz, using the test
layout in Figure 3, instability will occur if the supply line is not
decoupled with two high quality RF capacitors, a 0.1
μ
F monolithic
right at the V
CC
pin, and a 6.8
μ
F tantalum on the supply line. An
electrolytic is not an adequate substitute. At 10.7MHz, a 1
μ
F
tantalum has proven acceptable with this layout. Every layout must
be evaluated on its own merit, but don’t underestimate the
importance of good supply bypass.
At 455kHz, if the layout of Figure 3 or one substantially similar is
used, it is possible to directly connect ceramic filters to the input and
between limiter stages with no special consideration. At frequencies
above 2MHz, some input impedance reduction is usually necessary.
Figure 9 demonstrates a practical means.
As illustrated in Figure 10, 430
external resistors are applied in
parallel to the internal 1.6k
load resistors, thus presenting
approximately 330
to the filters. The input filter is a crystal type for
narrowband selectivity. The filter is terminated with a tank which
transforms to 330
. The interstage filter is a ceramic type which
doesn’t contribute to system selectivity, but does suppress wideband
noise and stray signal pickup. In wideband 10.7MHz IFs the input
filter can also be ceramic, directly connected to Pin 16.
In some products it may be impractical to utilize shielding, but this
mechanism may be appropriate to 10.7MHz and 21.4MHz IF. One
of the benefits of low current is lower radiated field strength, but
lower does not mean non-existent. A spectrum analyzer with an
active probe will clearly show IF energy with the probe held in the
proximity of the second limiter output or quadrature coil. No specific
recommendations are provided, but mechanical shielding should be
considered if layout, bypass, and input impedance reduction do not
solve a stubborn instability.
The final stability consideration is phase shift. The phase shift of the
limiters is very low, but there is phase shift contribution from the
quadrature tank and the filters. Most filters demonstrate a large
phase shift across their passband (especially at the edges). If the
quadrature detector is tuned to the edge of the filter passband, the
combined filter and quadrature phase shift can aggravate stability.
This is not usually a problem, but should be kept in mind.
Quadrature Detector
Figure 7 shows an equivalent circuit of the SA614A quadrature
detector. It is a multiplier cell similar to a mixer stage. Instead of
mixing two different frequencies, it mixes two signals of common
frequency but different phase. Internal to the device, a constant
amplitude (limited) signal is differentially applied to the lower port of
the multiplier. The same signal is applied single-ended to an
external capacitor at Pin 9. There is a 90
°
phase shift across the
plates of this capacitor, with the phase shifted signal applied to the
upper port of the multiplier at Pin 8. A quadrature tank (parallel L/C
network) permits frequency selective phase shifting at the IF
frequency. This quadrature tank must be returned to ground through
a DC blocking capacitor.
The loaded Q of the quadrature tank impacts three fundamental
aspects of the detector: Distortion, maximum modulated peak
deviation, and audio output amplitude. Typical quadrature curves
are illustrated in Figure 12. The phase angle translates to a shift in
the multiplier output voltage.
Thus a small deviation gives a large output with a high Q tank.
However, as the deviation from resonance increases, the
non-linearity of the curve increases (distortion), and, with too much
deviation, the signal will be outside the quadrature region (limiting
the peak deviation which can be demodulated). If the same peak
deviation is applied to a lower Q tank, the deviation will remain in a
region of the curve which is more linear (less distortion), but creates
a smaller phase angle (smaller output amplitude). Thus the Q of the
quadrature tank must be tailored to the design. Basic equations and
an example for determining Q are shown below. This explanation
includes first-order effects only.
Frequency Discriminator Design Equations for
SA614A
V
OUT
SR00333
Figure 11.
V
O
=
C
S
C
P
+ C
S
1 +
ω
1
Q
1
S
S
+
2
(
)
1
ω
1
V
IN
(1a)
L(C
P
+ C
S
)
Q
1
= R (C
P
+ C
S
)
ω
1
where
ω
1
=
1
(1b)
(1c)
相關(guān)PDF資料
PDF描述
SA615 High performance low power FM IF system(高性能低功耗FM IF系統(tǒng))
SA621DH
SA621 1GHz - Low voltage LNA, mixer and VCO
SA624D High performance low power FM IF system with high-speed RSSI
SA624 High performance low power FM IF system with high-speed RSSI
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
SA-6-1-4BC 制造商:Cooper Bussmann 功能描述:FUSTAT ADAPTER - Bulk
SA615 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:High performance low power mixer FM IF system
SA615D 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:High performance low power mixer FM IF system
SA615D,602 功能描述:射頻無線雜項 HI PERF LP MIXER FM IF SYSTEM RoHS:否 制造商:Texas Instruments 工作頻率:112 kHz to 205 kHz 電源電壓-最大:3.6 V 電源電壓-最小:3 V 電源電流:8 mA 最大功率耗散: 工作溫度范圍:- 40 C to + 110 C 封裝 / 箱體:VQFN-48 封裝:Reel
SA615D,623 功能描述:上下轉(zhuǎn)換器 HI PERF LP MIXER FM IF SYSTEM RoHS:否 制造商:Texas Instruments 產(chǎn)品:Down Converters 射頻:52 MHz to 78 MHz 中頻:300 MHz LO頻率: 功率增益: P1dB: 工作電源電壓:1.8 V, 3.3 V 工作電源電流:120 mA 最大功率耗散:1 W 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFP-128
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。

采購需求

(若只采購一條型號，填寫一行即可)

發(fā)布成功！您可以繼續(xù)發(fā)布采購。也可以進(jìn)入我的后臺，查看報價

發(fā)布成功！您可以繼續(xù)發(fā)布采購。也可以進(jìn)入我的后臺，查看報價

*型號 *數(shù)量 廠商 批號 封裝
添加更多采購

我的聯(lián)系方式

*
*
*