MITEL SL1714, SL1714C, SL1714KG, SL1714MH1P, SL1714MH1Q Datasheet

The SL1714 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 SL1714 is optimised to drive a dual ADC converter
such as the VP216.

The SL1714 utilises a standard MP16 plastic package,
the SL1714C a power MH16 plastic package.

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)

APPLICATIONS

■ Satellite receiver systems

■ Data communications systems

■ Cable systems

ORDERING INFORMATION

SL1714/KG/MP1S (Sticks)
SL1714/KG/MP1T (Tape and Reel)
SL1714C/KG/MH1P (Sticks)
SL1714C/KG/MH1Q (Tape and Reel)

Fig. 1 Pin allocation SL1714

MP16

SL1714

116

VCCC

AGC
IOUT

VEEA

IFINB

IFIN

IVCCA

QOUT

VEEC

VCCB
VCODIS
VCO B
VCO A
VEEB
PSCAL
PSCALB

MH16

SL1714

1

16

VCCC

AGC
IOUT

VEEA

IFINB

IFIN

IVCCA

QOUT

VEEC

VCCB
VCODIS

VCO B
VCO A

VEEB
PSCAL
PSCALB

C

SL1714

Quadrature Downconverter

Advance Information

Supersedes November 1997 issue 1.7 DS4619 - 2.0 April 1998

2

SL1714

QUICK REFERENCE DATA

Characteristic Value Units

Input noise figure, DSB 17 dB
Maximum conversion gain 48 dB
Minimum conversion gain 28 dB
IP32T output referred +8 dBV
Output clip voltage 1.5 V
Gain match up to 30MHz ± 0.5 dB
Phase match up to 15MHz ± 1 deg
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 SL1714 block diagram

AGC

IFIN

VCODIS

VCO

AGC

AGC

÷32

LO

0 deg 90 deg

Quadrature
generator

PSCALB

PSCAL

Q OUT

I OUT

IFINB

VCO

3

SL1714

FUNCTIONAL DESCRIPTION

The SL1714 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 SL1714 oscillator can be used with either a varactor
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 applications 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 application 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 12 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 SL1714 must
not exceed a parallel combination of 1KΩ and 15pF. 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 numbers 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.

4

SL1714

Fig.3 Typical RF input impedance

-j0.2

0

+j0.2

+j0.5

+j1

+j2

-j2

-j1

-j0.5

0.2 0.5

1

START 350 MHz

STOP 650 MHz

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

X

5

SL1714

Fig.4 Typical AGC characteristic

Fig. 5 Typical baseband output impedance

-j0.2

0

+j0.2

+j0.5

j1

+j2

-j2

-j1

-j0.5

0.2

0.5

1

X

X

1

2

1 1MHz

2 15MHz

3 30MHz

X

3

GAIN (dB)

25.00

30.00

33.00

40.00

45.00

50.00

012345

V

agc (V)

6

SL1714

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

O/P

Vcc

Vref

AGC

50k

Vref

VCO

VCO

2x20k

VCODIS

55k

Vref