參數(shù)資料
型號(hào)： ZL20200LDE
廠(chǎng)商： Zarlink Semiconductor Inc.
英文描述： Dual Band IS136/AMPS Transceiver
中文描述： 雙頻IS136/AMPS收發(fā)器
文件頁(yè)數(shù)： 14/52頁(yè)
文件大?。?/td> 516K
代理商： ZL20200LDE
ZL20200
Data Sheet
14
Zarlink Semiconductor Inc.
1.2 Transmit
Transmit operation is similar for all modes and a detailed diagram is shown in Figure 7. This diagram also shows
the UHF LO generation circuit blocks. A summary of the characteristics of the transmit path circuit blocks are given
in the table below. All circuit blocks are differential with the exception of the transmit RF outputs.
Differential baseband transmit I and Q signals from a baseband processor are input to the ZL20200. The baseband
signals are passed through filters. A quadrature modulator modulates these baseband signals on to the transmit IF
which is typically around 200 MHz. This modulated IF signal is passed through an on chip low pass filter which
removes harmonics of the IF and then into a gain controlled amplifier. This amplifier is controlled by an external
analog signal and provides greater than 60 dB gain control The output of the gain controlled amplifier can then be
up-converted to RF or alternatively the output can be sent to an off chip filter to provide further filtering and removal
of noise before up-conversion. This filter is a parallel tuned circuit as shown in Figure 7. The choice of component
values is dependent on the IF frequency being used. The filter output is then fed back on chip to the up-converter. A
SSB mixer is used for the up-conversion to remove the unwanted image. High side or low side LO injection can be
selected.
A buffer amplifier after the up-conversion provides a further 9 dB gain control in 3 dB increments. This gain is
programmable via the serial bus and can be used to optimize noise and linearity performance in particular
applications. Finally there are two RF output stages for 900 MHz and 1900 MHz frequency bands. Each RF output
is single ended and requires a simple matching network. The supply current of the output stages is automatically
reduced at low transmit gain control voltages improving the efficiency of the output buffer at low output power
levels. The supply current of the output buffer can also be controlled via the serial bus. This allows the supply
current to be reduced which is particularly useful when using AMPS where the linearity performance is less critical.
The FM modulation for AMPS can be done using I,Q modulation if available. Alternatively FM modulation can be
applied direct to the transmit IF VCO. The loop bandwidth for the transmit VHF PLL should be low (~100 Hz) to
ensure the PLL does not remove the modulation. A dc voltage should be applied across the Tx I+, Tx I- and the Tx
Q+, Tx Q- inputs to switch the modulator and generate an IF carrier signal. With a baseband gain of 0 dB a dc
voltage of at least 1.5 volts should be applied; a lower voltage can be used with the baseband gain increased to
compensate. It is assumed that this bias can be provided by the baseband however if this is not possible then the
simplest solution is to connect 200 kohm resistors between I+, Q+ inputs and Vcc and 200 kohm resistors between
I-, Q- inputs and ground, assuming the transmit outputs from the baseband are in a high impedance state in AMPS
Circuit
Block
Gain
(dB)
Bandwidth
(If Applicable)
Description
Reconstruction Filters
0 -12
IS136/AMPS
12.5 kHz
Baseband input stage. Gain is programmable in 3 dB steps from
0 to 12 dB.
There is also a by-pass mode so that the baseband I and Q signal can
go direct to the modulator
Quadrature Modulator
Generates a modulated IF signal
Transmit IF
400 MHz
Provides gain control at IF frequency. This stage also includes a low
pass filter to remove harmonics and spurii from modulator output.
This stage also includes a buffered IF output which can be used with an
external IF filter.
Up-converter
SSB up-converter to RF frequency. The IF path includes phase shift
networks for the up-converter. This stage also includes the input circuit
from the optional external IF filter
Transmit RF
The 900 MHz and 1900 MHz RF stages each consist of 2 stages. The
first stage gain be set from -6 to +3 dB in 3 dB steps. Output stage
current is controlled by agc signal to reduce current consumption at low
output power levels. Each output stage requires an external
degeneration inductor
Table 3 - Transmit Circuit blocks
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
ZL20200LDF 制造商:ZARLINK 制造商全稱(chēng):Zarlink Semiconductor Inc 功能描述:Dual Band IS136/AMPS Transceiver
ZL20200LDF1 制造商:Microsemi Corporation 功能描述:
ZL20200LDG 制造商:ZARLINK 制造商全稱(chēng):Zarlink Semiconductor Inc 功能描述:Dual Band IS136/AMPS Transceiver
ZL20200LDG1 制造商:Microsemi Corporation 功能描述:
ZL20250 制造商:ZARLINK 制造商全稱(chēng):Zarlink Semiconductor Inc 功能描述:2.5G Multimode Transceiver
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