CE5037

Data Sheet

5

Intel Corporation

1.0

Circuit Description

1.1

Functional Description

The CE5037 is a single chip wide band direct conversion tuner with integral RF bypass optimised for digital satellite

receiver systems. It provides excellent signal handling capability in the presence of high composite signal levels.

The device offers a highly integrated solution for a satellite tuner incorporating a low phase noise PLL frequency

synthesizer, the quadrature down converter, a fully integrated local oscillator, and programmable baseband channel

filters. A minimal number of additional peripheral components are required. The crystal reference source can be

also used as the reference for the demodulator.

The CE5037 contains both hardware and software power down modes.

1.2

Signal Path

1.2.1

RF Input

The tuner RF input signal at a frequency of 950 – 2150 MHz is fed to the CE5037 RF input pre-amplifier stage.

The signal handling is designed such that no tracking filter is required to offer immunity to input signal composite

overload.

The RF input amplifier feeds an AGC stage, which provides RF gain control. There is additional gain adjustment in

the baseband section. The total AGC gain range will guarantee an operating dynamic range of –92 to –10 dBm.

The RF AGC in the CE5037 is divided into two stages. The first stage is a continually variable gain control stage,

and provides the main system AGC set under control of the analogue AGC signal generated by the demodulator

section. The second stage is a programmable gain stage to reduce RF gain by 10 dB. This would normally be used

when an external LNA is being used to improve system sensitivity.

The analogue RF AGC is optimised for S/N and S/I performance across the full dynamic range. Typical RF AGC

characteristic and variation of IIP3, IIP2 and NF are shown in Section 8 - Typical Performance Curves.

The output of the AGC stage is coupled to the quadrature mixer where the RF signal is mixed with quadrature local

oscillator signals generated by the on-board local oscillator.

1.2.2

Baseband

The outputs of the quadrature down converter are passed through the baseband filters followed by a programmable

baseband gain stage.

The baseband paths are DC coupled. An integrated DC correction loop prevents saturation due to local oscillator

self-mixing in the converter section. No external components are required for dc correction.

between the I and Q channels. The filters are fully programmable for 3 dB bandwidths from 6 MHz to 43 MHz. The

recommended filter bandwidth is related to the required symbol rate by the following equation.

This equation makes no allowance for LNB tuning offset at low symbol rates < 10 MS/s.

8

.

0

2

35

.

1

3

×

×

=

−

SymbolRate

fc

width

FilterBand

dB