Table 1- -4: Input; Down Converter 3 - Tektronix RSA3303A Service Manual

Theory of Operation
Down Converter
RF3 Module
RF2 Module
RF5 Module
3- 2
The RF3 module contains the 1
er, and other components. After level adjustment in the RF input circuit, the
input signal is applied to the 1
signal is frequency-converted into 1
st
frequency of 1 Local Oscillator is controlled with a synthesizer (RF4 module)
st
in this case, so that 1 IF signal is always maintained at 4232 MHz. After this,
st
the 1 IF signal passes through the 1
mately 10 dB, and is sent to the 2
In baseband, an input signal enters the 1
switched with a relay and the signal is sent directly to the A10 A/D board for
A/D conversion. In RF1 band, an input signal goes through all converters (1
nd rd
2 , and 3 ). In RF2/3 band, an input signal is directly frequency-converted by
st
the 1 Converter into the 2
Converter, bypassing the 2
The RF2 module consists of the 2
st
Oscillator. The 1 IF signal sent from the 1
Band-pass Filter and a Low-pass Filter for removal of unnecessary frequency
st
bands. After this, the 1
st
the 1 IF signal is mixed with the 2
nd
the 2 IF signal of 422 MHz. Same with the case of 1
nd
frequency of 2 Local Oscillator is controlled with a synthesizer circuit (RF4
module) to stabilize LO output frequency.
nd
The 2 IF signal is sent to the 3
rd
mixed with the 3 LO signal and frequency-converted into the 3
39 MHz. After selected with a band-switching relay located at the input section
rd
of the 3 Converter, the 2
RF2/3 band mode is also frequency-converted into the 3
The RF5 module consists of the 3
Reference Oscillator. The Oscillator block contains the 3
an oscillator of Sampling Clock signal to be supplied to A/D Converter.
The Gain block consists of a Step Amplifier of 10 dB/step with the maximum
gain of 50 dB and a Step Attenuator with the maximum attenuation of - -30 dB.
This block maintains the 3
appropriate level, and adjusts the accuracy of conversion gain.
rd
Both the 3 LO signal and A/D clock signal generated in the Oscillator block are
highly stabilized signals locked with a 10 MHz reference signal, and are output
rd
to the 3 Converter and A10 A/D board, respectively.
st st
Converter, 1 Local Oscillator, 1
st
Converter. Mixed with 1
st
IF signal of 4232 MHz. Oscillation
st
IF Amplifier that has a gain of approxi-
nd
Converter (RF2 module).
st
Converter. Then the signal path is
nd
IF signal of 422 MHz, then sent directly to 3
nd
Converter.
nd
Converter, 3
st
Converter passes through a
nd
IF signal enters the 2
nd
LO signal and frequency-converted into
rd
Converter. In the 3
nd
IF signal directly sent from the 1
rd
IF Gain block, Oscillator block, and 10 MHz
rd
IF signal to be sent to A/D Converter at an
RSA3303A & RSA3308A Service Manual
st
IF Amplifi-
st
LO signal, the input
rd nd
Converter, and 2 Local
nd
Converter. In the 2 Converter,
st
Local Oscillator,
rd
Converter, the signal is
rd
IF signal of
st
Converter in
rd
IF signal of 39 MHz.
rd
Local Oscillator and
st
,
rd