L8200

Preliminary

LINEAR INTEGRATED CIRCUIT

UNISONICTECHNOLOGIESCO.,LTD

6 of 6

www.unisonic.com.tw

QW-R123-017.e



SINGLE UNIVERSAL BLOCK DIAGRAM

The following block diagram below shows the main elements of a single universal LNB. A single chip solution

provides all the FET and mixer bias, control signal detect for polarization and band selection and all the necessary

power management functions required within a single universal LNB.

UTC

L8200

Vertical

Horizontal

Gain Stages

GaAs/HEMT FET

Active

Mixer

IF Gain Stage

LB Osc

HB Osc

Set-top Box

Receiver

Polarization and band switching on the UTC L8200 uses the standard 13~17V and 22kHz as defined by Astra.

The exception is that the devices voltage detector has a much tighter tolerance than required to increase field

reliability.

detection. The IC’s is self powering via an internal regulator which utilizes the 13~17V control voltage from the

power supply for the remaining element of the LNB such as the IF amplifiers. The 13~17V from the receiver is feed

via a tight tolerance voltage detector with integrated filtering which removes unwanted signals or interference. The

results from the detectors output enables one of 2 bias circuits to turn one of either Fet1 or FET2 on. The internal

tone detector allows the device to detect the 22kHz tone which is superimposed on the LNB power line (13~17V

signal), this is achieved with no external filtering components. The tone detector rejects all unwanted signals

including transients from other parts of the LNB system. The tone detector controls a drive circuits which powers and

one of two oscillators, normally used to switch between low and high band in universal applications. The functional

table below shows the operation of the FET and Mixer bias, oscillator output and the LNB power supply.



FUNCTION TABLE

INPUTS

OUTPUTS

FIN (kHZ)

FET1

FET2

FET3

MIXER

LB(V)

HB(V)

<14.1

0

Disabled

Active

Active

Active

5.0

0

5.0

>15.4

0

Active

Disabled

Active

Active

5.0

5.0

<14.1

22

Disabled

Active

Active

Active

0

5.0

5.0

>15.4

22

Active

Disabled

Active

Active

0

5.0

5.0

UTC assumes no responsibility for equipment failures that result from using products at values that

exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or

other parameters) listed in products specifications of any and all UTC products described or contained

herein. UTC products are not designed for use in life support appliances, devices or systems where

malfunction of these products can be reasonably expected to result in personal injury. Reproduction in

whole or in part is prohibited without the prior written consent of the copyright owner. The information

presented in this document does not form part of any quotation or contract, is believed to be accurate

and reliable and may be changed without notice.