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参数资料
| 型号： | AD8343-EVAL |
| 厂商： | Analog Devices, Inc. |
| 英文描述： | DC-to-2.5 GHz High IP3 Active Mixer |
| 中文描述： | DC至2.5GHz的高IP3有源混频器 |
| 文件页数： | 12/27页 |
| 文件大小： | 394K |
| 代理商： | AD8343-EVAL |
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REV. 0
AD8343
–12–
CIRCUIT DESCRIPTION
The AD8343 is a mixer intended for high-intercept applications.
The signal paths are entirely differential and dc-coupled to permit
high-performance operation over a broad range of frequencies;
the block diagram (Figure 1) shows the basic functional blocks.
The bias cell provides a PTAT (proportional to absolute tem-
perature) bias to the LO Driver and Core. The LO Driver
consists of a three-stage limiting differential amplifier that pro-
vides a very fast (almost square-wave) drive to the bases of the
core transistors.
The AD8343 core utilizes a standard architecture in which the
signal inputs are directly applied to the emitters of the transistors in
the cell (Figure 7). The bases are driven by the hard-limited LO
signal that directs the transistors to steer the input currents into
periodically alternating pairs of output terminals, thus providing
the periodic polarity reversal that effectively multiplies the signal
by a square wave of the LO frequency.
BIAS
AD8343
VPOS
DCPL
PWDN
LOIP
LOIM
INPP
INPM
OUTP
OUTM
COMM
MIXER
CORE
LO
DRIVER
Q1 Q2
Q3 Q4
Figure 1. Topology
To illustrate this functionality, when LOIP is positive, Q1 and
Q4 are turned ON, and Q2 and Q3 are turned OFF. In this
condition Q1 connects I
INPP
to OUTM and Q4 connects I
INPM
to OUTP. When LOIP is negative the roles of the transistors
reverse, steering I
INPP
to OUTP and I
INPM
to OUTM. Isolation
and gain are possible because at any instant the signal passes
through a common-base transistor amplifier pair.
Multiplication is the essence of frequency mixing; an
ideal
multi-
plier would make an excellent mixer. The theory is expressed in
the following trigonometric identity:
sin
(
ω
sig
t
)
sin
(
ω
LO
t
) = 1/2 [
cos
(
ω
sig
t –
ω
LO
t
) –
cos
(
ω
sig
t
+
ω
LO
t
)]
This states that the product of two sine-wave signals of different
frequencies is a pair of sine waves at frequencies equal to the
sum and difference of the two frequencies being multiplied.
Unfortunately, practical implementations of analog multipliers
generally make poor mixers because of imperfect linearity and
because of the added noise that invariably accompanies attempts
to improve linearity. The best mixers to date have proven to be
those that use the LO signal to periodically reverse the polarity
of the input signal.
In this class of mixers, frequency conversion occurs as a result
of multiplication of the signal by a square wave at the LO
frequency. Because a square wave contains odd harmonics in
addition to the fundamental, the signal is effectively multiplied
by each frequency component of the LO. The output of the
mixer will therefore contain signals at F
LO
±
F
sig
, 3
×
F
LO
±
F
sig
,
5
×
F
LO
±
F
sig
, 7
×
F
LO
±
F
sig
, etc. The amplitude of the compo-
nents arising from signal multiplication by LO harmonics falls
off with increasing harmonic order because the amplitude of a
square wave’s harmonics falls off.
An example of this process is illustrated in Figure 2. The first
pane of this figure shows an 800 MHz sinusoid intended to
represent an input signal. The second pane contains a square
wave representing an LO signal at 600 MHz which has been
hard-limited by the internal LO driver. The third pane shows
the time domain representation of the output waveform and the
fourth pane shows the frequency domain representation. The
two strongest lines in the spectrum are the sum and difference
frequencies arising from multiplication of the signal by the LO’s
fundamental frequency. The weaker spectral lines are the result
of the multiplication of the signal by various harmonics of the
LO square wave.
FREQUENCY
DOMAIN
LOCAL
OSCILLATOR
TIME
DOMAIN
SIGNAL
SIG LO
SIG LO
FREQUENCY
S
–
S
3
–
5
–
3
7
–
5
Figure 2. Signal Switching Characteristics of the AD8343
相关PDF资料 |
PDF描述 |
|---|---|
| AD8343ARU | DC-to-2.5 GHz High IP3 Active Mixer |
| AD8343ARU-REEL7 | DC-to-2.5 GHz High IP3 Active Mixer |
| AD8344 | Active Receive Mixer 400 MHz to 1.2 GHz |
| AD8344-EVAL | Active Receive Mixer 400 MHz to 1.2 GHz |
| AD8344ACPZ-REEL7 | Active Receive Mixer 400 MHz to 1.2 GHz |
相关代理商/技术参数 |
参数描述 |
|---|---|
| AD8343-EVALZ | 制造商:Analog Devices 功能描述:AD8343 EVALUATION BOARD - Bulk |
| AD8344 | 制造商:AD 制造商全称:Analog Devices 功能描述:Active Receive Mixer 400 MHz to 1.2 GHz |
| AD8344ACPZ | 制造商:Analog Devices 功能描述:UP/DOWN CONV MIXER 5V 1.2GHZ 16LFCSP EP - Tape and Reel 制造商:Analog Devices 功能描述:IC SM RF MIXER 800MHZ |
| AD8344ACPZ | 制造商:Analog Devices 功能描述:IC RF MIXER 800MHZ SMD LFCSP-16 |
| AD8344ACPZ-REEL7 | 功能描述:IC MIXER 400MHZ-1.2GHZ 16-LFCSP RoHS:是 类别:RF/IF 和 RFID >> RF 混频器 系列:AD8344 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:100 系列:- RF 型:W-CDMA 频率:2.11GHz ~ 2.17GHz 混频器数目:1 增益:17dB 噪音数据:2.2dB 次要属性:- 电流 - 电源:11.7mA 电源电压:2.7 V ~ 3.3 V 包装:托盘 封装/外壳:12-VFQFN 裸露焊盘 供应商设备封装:12-QFN-EP（3x3） |
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