MITEL SL1711, SL1711B, SL1711KG, SL1711MH1P, SL1711MH1Q Datasheet

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The SL1711 is a quadrature downconverter, intended primarily for application in professional and consumer digital satellite tuners.

The device contains all elements necessary, with the exception of external local oscillator tank to form a complete system operating at standard satellite receiver intermediate frequencies. It is intended for use with external carrier recovery.

The device includes a low noise RF input amplifier, a reference VCO with prescaler output buffer and In-phase and Quadrature mixers with baseband buffer amplifiers containing AGC gain control.

The SL1711 is optimised to drive a dual ADC converter such as the VP216.

The SL1711 utilises a power MP package, whereas the SL1711B variant uses a standard MP16 plastic package and features a revised operating temperature.

FEATURES

■ Single chip system for wideband quadrature

downconversion

■ Compatible with all standard high IF frequencies

■ Excellent gain and phase match up to 30MHz

baseband

■ High output referred linearity for low distortion and

multi channel application

■ Simple low component application

■ Fully balanced low radiation design with fully

integrated quadrature generation

■ High operating input sensitivity

■ On-board AGC facility

■ On chip oscillator for varactor tuning or SAW

resonator operation

■ ESD protection (Normal ESD handling procedures

should be observed)

MH16

SL1711

116

VCCC

AGC IOUT

VEEA

IFINB

IFIN

IVCCA

QOUT

VEEC

VCCB VCODIS VCO B VCO A VEEB PSCAL PSCALB

APPLICATIONS

■ Satellite receiver systems

■ Data communications systems

■ Cable systems

ORDERING INFORMATION

SL1711/KG/MH1P (Sticks) SL1711/KG/MH1Q (Tape and Reel) SL1711B/KG/MP1S (Sticks) SL1711B/KG/MP1T (Tape and Reel)

Fig. 1 Pin allocation

MP16

SL1711B

116

VCCC

AGC IOUT

VEEA

IFINB

IFIN

IVCCA

QOUT

VEEC

VCCB VCODIS VCO B VCO A VEEB PSCAL PSCALB

SL1711

Quadrature Downconverter

Preliminary Information

Supersedes November 1996 version, DS4032 - 1.6 DS4032 - 4.0 October 1997

SL1711

QUICK REFERENCE DATA

Characteristic Value Units

Input noise figure, DSB 17 dB Maximum conversion gain 44 dB Minimum conversion gain 28 dB IP32T output referred +8 dBV Output clip voltage 1.5 Vp-p Gain match up to 22MHz ± 0.3 dB Gain match up to 30MHz ± 0.5 dB Phase match up to 30MHz ± 1.5 deg Gain flatness up to 30MHz ± 0.5 dB VCO phase noise, SSB @ 10kHz offset - 96 dBc/Hz Prescaler division ratio 32 Prescaler output swing 1.6 Vp-p

Fig. 2 SL1711 block diagram

AGC

IFIN

VCODIS

VCOA

AGC

÷32

0 deg 90 deg

Quadrature generator

PSCALB

PSCAL

Q OUT

I OUT

IFINB

VCOB

SL1711

FUNCTIONAL DESCRIPTION

The SL1711 is a wideband quadrature downconverter, optimised for application in both professional and consumer digital satellite receiver systems and requiring a minimum external component count. It contains all the elements required for construction of a quadrature demodulator, with the exception of tank circuit for the local oscillator.

A block diagram is shown in Fig. 2.

The SL1711 oscillator can be used with either a varator tuned tank circuit or with a SAW resonator. Both configurations are described in the Application Notes section of this Data Sheet.

A typical digital satellite tuner application from tuner input to data transport stream is shown in Fig. 13

In normal application the second satellite IF frequency of typically 402.75 or 479.5 MHz is fed from the tuner SAW filter to the RF preamplifier, which is optimised for impedance match and signal handling. The amplifier output signal is then split into two balanced channels to drive the In-phase and Quadrature mixers. The typical RF input impedance is shown in Fig. 3

In-phase and Quadrature LO signals for the mixers are derived from the on board local oscillator, which uses an external varactor tuned resonant network and is optimised for low phase noise. The VCO also drives an on board divide by 32 prescaler whose outputs can be used for driving an external PLL control loop for the VCO, where the PLL loop is contained within the QPSK demodulator, for example the VP305. For optimum performance in the varactor tuned application the VCO should be fully symmetric. The VCO has a disable facility by grounding pin 15, VCODIS; in normal applications this pin is pulled to Vcc via a 4K7 resistor.

The mixer outputs are fed to balanced baseband AGC amplifier stages, which provide for a minimum of 16 dB of AGC control. The typical AGC characteristic is shown in Fig. 4.

These amplifiers then feed a low output impedance true differential to single-ended converter output stage. In normal application the output can be either directly AC coupled to the ADC converter such as the VP216, which will generally have a high input impedance, or to drive an anti alias filter. In this later case the maximum load presented to the SL1711 must not exceed a parallel combination of 1KΩ and 20pF. The typical baseband output impedance is contained in Fig. 5.

It is recommended that the device is operated with an output amplitude of 760mV under lock conditions.

Under transient conditions the output should not exceed the clipping voltage.

Input and output interface circuitry is contained in Fig. 6.

The typical key performance figures at 480 MHz IF, 5V Vcc, 1 kΩ load and 25 deg C ambient are contained in table headed 'QUICK REFERENCE DATA'. With SAWR oscillator application the gain and phase match performance will typically exceed these numbers.

SL1711

Fig.3 Typical RF input impedance

-j0.2

+j0.2

+j0.5

+j1

+j2

-j2

-j1

-j0.5

0.2 0.5

START 350 MHz

STOP 650 MHz

Marker 1 480MHz Zreal = 96Ω Zimag = 54Ω

SL1711

Fig.4 Typical AGC characteristic

Fig. 5 Typical baseband output impedance

-j0.2

+j0.2

+j0.5

+j2

-j2

-j1

-j0.5

0.2

0.5

1 1MHz

2 15MHz

3 30MHz

CONVERSION GAIN dB

1.25

1.5

1.75

2.25

2.5

2.75

3.25

3.5

3.75

4.25

4.5

AGC CONTROL VOLTS

SL1711

IF Input

VCO

I & Q baseband output

VCO disable input

Prescaler outputs

AGC input

Fig. 6 I/O port peripheral circuitry

IFINB

IFIN

Vcc

O/P

Vcc

Vref

AGC

50k

Vref

VCO

2x20k

VCODIS

55k

Vref

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