参数资料
型号: AD8339ACPZ-RL
厂商: ANALOG DEVICES INC
元件分类: 调制器/解调器
英文描述: 0 MHz - 50 MHz RF/MICROWAVE I/Q DEMODULATOR
封装: 6 X 6 MM, ROHS COMPLIANT, MO-220-VJJD-2, LFCSP-40
文件页数: 17/36页
文件大小: 2970K
代理商: AD8339ACPZ-RL
AD8339
Rev. A | Page 24 of
36
APPLICATIONS INFORMATION
The AD8339 is the key component of a phase shifter system
that aligns time-skewed information contained in RF signals.
Combined with a variable gain amplifier (VGA) and a low noise
amplifier (LNA) as in the AD8332/AD8334/AD8335 VGA
family, the AD8339 forms a complete analog receiver for a high
performance ultrasound CW Doppler system.
LOGIC INPUTS AND INTERFACES
The SDI, SCLK, SDO, CSB, and RSET pins are CMOS com-
patible to 1.8 V. The threshold of the RSTS pin is 1.5 V with a
hysteresis of ±0.3 V. Each logic input pin is Schmitt trigger
activated, with a threshold centered at ~1.3 V and a hysteresis
of ±0.1 V around this value.
The only logic output, SDO, generates a signal that has a logic
low level of ~0.2 V and a logic high level of ~1.9 V to allow for
easy interfacing to the next AD8339 SDI input. Note that the
capacitive loading for the SDO pin should be kept as small as
possible (<5 pF), ideally only a short trace to the SDI pin of the
next chip. The output slew is limited to approximately ±500 μA,
which limits the speed when a large capacitor is connected.
Excessive values of parasitic capacitance on the SDO pin can
affect the timing and loading of data into the SDI input of the
next chip.
RESET INPUT
The RSET pin is used to synchronize the LO dividers in AD8339
arrays. Because they are driven by the same internal LO, the four
channels in any AD8339 are inherently synchronous. However,
when multiple AD8339s are used, it is possible that their dividers
wake up in different phase states. The function of the RSET pin
is to phase align all the LO signals in multiple AD8339s.
The 4LO divider of each AD8339 can be initiated in one of four
possible states: 0°, 90°, 180°, or 270° relative to other AD8339s.
The internally generated I/Q signals of each AD8339 LO are
always at a 90° angle relative to each other, but a phase shift can
occur during power-up between the dividers of multiple
AD8339s used in a common array.
The LO divider reset function has been improved in the AD8339
compared with the AD8333. The RSET pin still provides an
asynchronous reset of the LO dividers by forcing the internal
LO to hang; however, in the AD8339, the LO reset function is
fast and does not require a shutdown of the 4LO input signal.
The RSET mechanism also allows the measurement of non-
mixing gain from the RF input to the output. The rising edge of
the active high RSET pulse can occur at any time; however, the
duration should be ≥20 ns minimum. When the RSET pulse
transitions from high to low, the LO dividers are reactivated on
the next rising edge of the 4LO clock. To guarantee synchronous
operation of an array of AD8339s, the RSET pulse must go low
on all devices before the next rising edge of the 4LO clock.
Therefore, it is best to have the RSET pulse go low on the falling
edge of the 4LO clock; at the very least, the tSETUP should be
≥5 ns. An optimal timing setup is for the RSET pulse to go high
on a 4LO falling edge and to go low on a 4LO falling edge; this
gives 10 ns of setup time even at a 4LO frequency of 50 MHz
(12.5 MHz internal LO).
Check the synchronization of multiple AD8339s using the
following procedure:
1.
Activate at least one channel per AD8339 by setting the
appropriate channel enable bit in the serial interface.
2.
Set the phase code of all AD8339 channels to the same
logic state, for example, 0000.
3.
Apply the same test signal to all devices to generate a sine
wave in the baseband output and measure the output of
one channel per device.
4.
Apply an RSET pulse to all AD8339s.
5.
Because all the phase codes of the AD8339s should be the
same, the combined signal of multiple devices should be N
times greater than a single channel. If the combined signal
is less than N times one channel, one or more of the LO
phases of the individual AD8339s is in error.
LO INPUT
The LO input is a high speed, fully differential analog input that
responds to differences in the input levels (and not logic levels).
The LO inputs can be driven with a low common-mode voltage
amplifier, such as the National Semiconductor DS90C401 LVDS
driver. The graph in Figure 22 shows the range of common-mode
voltages. Logic families such as TTL or CMOS are unsuitable
for direct coupling to the LO input.
相关PDF资料
PDF描述
AD8339ACPZ 0 MHz - 50 MHz RF/MICROWAVE I/Q DEMODULATOR
ADL5374ACPZ-WP 3000 MHz - 4000 MHz RF/MICROWAVE QUADRAPHASE MODULATOR
ADL5375-05ACPZ-R7 400 MHz - 6000 MHz RF/MICROWAVE I/Q MODULATOR
AH212-S8G 1800 MHz - 2400 MHz RF/MICROWAVE NARROW BAND MEDIUM POWER AMPLIFIER
AK1222 100 MHz - 900 MHz RF/MICROWAVE SINGLE BALANCED MIXER
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